Let's Talk Numbers: How Long Should Your Series Be?

Hi Folks,

Travis here. I've been talking about career planning and such lately, so I felt that today would be a good day to provide another tool for ya'll to use in that regard with an in-dept look at how the length of a series affects you commercially.

Obviously from an artistic standpoint your series should be as long as it needs to be, but there's a lot of wiggle room within that band. The idea here is to give you the information about how different novel lengths and series structure affect your bottom line as an author so that when that choice does come up, you have the tools to make the best one!

There's a lot of topics in this post that I've been dying to get onto the blog, so I'm really excited about this one. Let's go!

Let's Talk Numbers: How Long Should Your Series Be?

Are you ready for some graphs and charts?! Cause I am. It's been a while since I've dug into the nitty gritty behaviors of book sales. Today though, we are going to look at the economics and math that power our mainstay fiction series. 

We do so in the attempt to answer the question of, "how long should your series be?" Really, I hope to provide you with the tools to help answer that question for yourself.

Let's start with the most common genre fiction method of publishing: writing a sequential series of books. These are books that are meant to be read in order and they are published one after the other as they are written. (Since it's so common, this is going to be my assumed definition for the word "series" throughout this post.)

As I've talked about before, not everyone who reads book 1 in a series will go on to read book 2,3,4, etc. in the series. Since the books are sequential, this creates a funnel effect whereby 99% of people who read book 5 are people who've also read all the books before it. Same goes for any length of series be it three books or a hundred.

This creates a bit of mathematical tyranny for authors. Let's look at the theoretical earnings of a well written series that sells 1000 copies of its book 1.

(For fun, x10 units and royalties and it's pretty mid-list)

What these columns mean,

• Retention Rate = The percent of readers from the previous book who read the next one. For example, this chart says that 60% of people who read book 1 will go on to read book 2. I should disclaim that these rates you see here are very good. My examples assume that the series is excellently written.
• Royalties Earned = How much each individual book will earn in royalties in its first 9 months, which is about 70% of the royalties it'll earn in its first 2 years. Beyond that, the planning is totally different.
• Total Royalties = this is a running total of all royalties earned by all books. $12,454 is how much our test series will have made 9 months after book 7 comes out (it might earn more later, but we've found that 70% of a typical book's earnings happen during the first 9 months.)

This chart shows the diminishing returns on readership that a long-running and highly sequential series suffers from. Book 4 only earns half as much as book 1 does! And book 7 is only one third earning power. 

But do not despair!

Were this the true case of things, no one would write series except as purely artistic affairs. I had to show you this chart first to make everything else make sense. I'm sorry to mislead.

What's missing from this picture so far are two dynamics.

1. Series growth over time
2. Launching a new book grows the series better than anything else

Now, figuring out how many book 1's book 2's launch will sell is, quite frankly, impossible. It depends on a great deal of factors that have only marginally to do with how well book 1 did. All I can say is that if book 1 has a lot of good reviews, then books 2, 3, and so on will have a stronger launch effect on it.

For example, I bet a lot of NDFL readers come in from people who saw One Good Dragon Deserves Another on the kindle Hot New Releases list. The pull power of that list and Rachel's book on that list is impossible to estimate, but I can tell you that just putting One Good Dragon out there sold about 4000 extra copies of Nice Dragons than the book would have sold on its own without the sequel launch.

When we say books sell books, this is what we mean. Releasing a new book in a series gives all the previous titles a boost as new readers see the new book, get excited, realize it's number X in a series, and go take a look at the first one. Again, there's no 100% accurate way to tell how this will play out for every book. That said, though, I've done loads of research to bring to you, today, a reasonable estimation of what series growth can look like.

These numbers are based on a modest, new(ish), and indie mid-list author, which is why series growth goes up and then down. This chart assumes a new novel launch every 9 months.

a modest and partially-hypothetical mid-list

Series Growth is what's important here. In a nutshell, it's how many book 1's each release on that list sells due to the buzz and attention it's launch creates. Keep in mind (cause these numbers won't add up otherwise) that if book 1 sells 1000 copies, then book 2 also sells more and book 3 sells more and so on. This next chart shows how that effect was incorporated in my example.

This chart shows how all the books in the series grow, one launch at a time. Book 1 has 18000 sales at the time book 7 comes out. Though the fact that book 6 has 6299 readers when book 7 comes out is what matters for the size of book 7's launch.

Anyway, here's a chart of the estimated royalty earnings on said modestly mid-list indie series.

Keep in mind this is over 5+ years of writing and earning (aka, $30k/yr)

What's awesome is that you can see how just the growth from new launches keeps the series's earning power afloat. Book 7 here sells basically as well as book 5 did at its launch and better than books 3 and 4 at theirs, despite the reader drop off.

What lessons can we draw from this?

Reader Retention Rate Is Critical for Long Running Series

Wanna see something scary? Let's say that book 3 in this series was bad. Maybe it had crushing tension problems or killed off the star character. For whatever reason, a big chunk of people who read the first two novels just aren't finishing this one. An author's nightmare, right? Well, watch what happens to sales...

Here I changed the data so that only 40% of people who read book 3 go on to read book 4. Behold the death spiral that results. Not only did $80k in potential total earnings go up in smoke, but the series has utterly lost its staying power. It might never hit a high sales rank again, and I'm really under-estimating the compound negative effects here.

I cannot tell you how grateful I am that Rachel and I have never faced this situation. The thought of her writing a book 5 in this situation, knowing that it and the rest of the series is already doomed from a sales standpoint, is unthinkably horrible. 

Should you quit the series if this happens to you? I don't know. The situation is so crappy. The fans who've stuck it through deserve a finished series, but authors still need to eat and pay rent.

Now, some series can recover, just look at the Wheel of Time series. Book 1 was cool, but long and slow and hard as all heck to get through. Book 2 was mildly better, but most readers agree the series only really took off at book 3, which is also when Wheel of Time became a breakout success. TBH, this pattern is super rare and should not be counted on. Also, WoT came out during a different time in a different market to a different readership that expected different things from its Epic Fantasy. The current hot and crowded marketplace probably won't allow for this kind of long recovery anymore, which makes writing a really good first book all the more important.

But despite these risks...

Long Series Are Reliable Earners

We can all see that the earning power and staying power of a long series is solid. Long series are good at building readership. They are also predictable. I've looked at this retention rate thing a lot and I know that publishers monitor it as well. If the books are good, you can fairly accurately predict how many sales the next book will garner. The same cannot be said for a new series.

A new series is always a bigger gamble than a sequel will be. 

Sequels are reliable earners. But when a series is very sequential with each book requiring knowledge of previous books to make sense, this reliable nature can become reliably negative should the author mess up and release a stinker.

Longer series are a risky in terms of execution.

Hands down, I would recommend new authors stay away from doing 5 or 7 book series. Obviously, it can be done (Rachel's first series was five books long), but the bar for making it work is higher than it looks. Each book has to be very good, preferably great, to keep readers hooked and moving forward. That's a tough act to pull off once, let alone five or more times. The rewards of consistent earnings are there, but only for people who can execute a 5+ book story and not drop the ball even once.

This might sound unreasonable, but really it's mostly an experience thing IMO. I don't think many veteran authors would bat an eye at this concern. And that's great, because if you can successfully pull it off, a successful longer series can generate a reliable income for many years.

Earn power aside, though, there's a concrete strength possessed by longer series that you won't hear others talking about much...

The Marketing Power of Longer Series

How much would you pay to get someone to buy book 1 of your series?

This is important. If you spend $100 on Facebook ads and sell 10 books, how much money did you make? Tip: It's not 10x the royalty on that book.

The answer depends on how well you marketed to that customer (ie, are they a good fit for your novels?), how well your series moves readers along, and how long the series is. Look at this,

This shows how much money (adjusted) a reader buying book 1 will likely spend on the series as a whole. If the series has a good reader retention rate, then, on average, a new reader who reads all the way to the end will spend $7.26 total for the 3-book, $10.12 for the 5-book, and $12.44 for the 7-book series respectively.

I'm worried this chart is confusing, so here it is again, modeling the results of an ad campaign that sold 100 copies of book 1.

Let's go back to our opening question. In light of these numbers, would you spend $10 to convince one person to buy book 1?

For a trilogy, probably no. For a 5-book series, maybe. For a 7-book series? Definitely. I'll pay $10 to make $12 all day long.

But I'm assuming a lot here. I'm assuming you have a 7 book series that is well reviewed and has the great tension and reader investment management necessary to get people all the way to the end. I'm assuming your paid ads are written and targeted in a way that will land you good quality customers who will legit like your book. If you just get a ton of exposure with poor targeting, these numbers won't work out at all. Even if you can land that book 1 sale, badly targeted readers who aren't actually a good fit for your series will bail from it in much higher numbers than organically acquired readers (people who came in on their own through reviews, blurbs, and so forth) do.

Still, in the world of marketing and paid online ads, efficiency is hard to come by. It takes a lot of time and money to bring down the cost-per-sale of Facebook and Amazon ads.

We've also found that having more series out doesn't change this dynamic as much as you'd think. My best guess is that only 20% to 40% of Rachel's readers move from one of her series to another. I've heard other authors and panelists at RT2016 cite similar numbers.

So what does this do to the cost of bringing in new readers?

This chart shows the estimated results of an ad campaign that sold 100 copies of book 1 of series 1. My fictional author in this example also has a 5-book series and another 3-book series out that happy customers can move to once they are done reading series 1.

(Note that some customers might go straight from series 1 to series 3, and my example doesn't account for that. It's not actually that important for this discussion though. I changed the order around in excel just to see and the order makes an insignificant difference.)

You can see how fast and hard customers filter out after they complete the series that they came in on. Please keep in mind that we're only examining an ad campaign that tries to sell book 1 of series 1. This is not a model for the overall behavior of multiple series in general. We're examining just a single entry point into the author's sales funnel.

What is important here is that each customer conversion from the ad campaign above spends approx $8.86 on average on books by the author. Compare these 11 books vs the 7-book series example from above (which was $12.44 per customer), and that's the point I want to show off here,

Longer series are more efficient to market than shorter ones

Online advertising is hard. It's tough to get a return on your investment for any series, but the more books you have out there, the better your chances get. If you have lots of short series and stand alones, then your reader funnel has a lot of holes and places new readers can fall out of your work. But if you have a long series or multiple long series that suck readers in, then you're free to spend more advertising bucks acquiring each new reader because the chances of that reader buying and reading enough books to pay for the cost of getting them are that much higher.

Online ads are just one form of advertising, of course, but the same logic works for any form of advertising be it Bookbub or landing an Amazon Daily Deal or even having one of your books reviewed in the NYT. All of these are amazing opportunities to sell books, and the better your reader funnel is (ie, the more of those new readers you can hook and keep for multiple titles), the better your position for leveraging those strokes of good fortune.

So, better marketing and reliable earnings at the risks of increased execution challenge. That's series length economics in a nutshell for you all. Before we go, however, I'd like to talk about a couple of exciting and interesting special cases when it comes to series structure and length.

Special Case #1 - Episodic Series

There's a special kind of series out there that I absolutely have to talk about because this post is the perfect place to do so. You have all the context I could ask to appreciate it now.

In Romance, there is a type of long running series that can gain more readers with every book rather than lose them. This happens because, even though the books are all in the same series, each new title features a new main couple. This couple is related to all the others in a series often by blood as the number of bachelor brother quartets in Romance illustrates), but every book starts and finishes an enclosed plot line of its own, complete with Happily Ever After ending.

This stand alone nature allows new readers to enter the series at any books, but since previous and future couples (and the world itself in the case of Paranormals) feature heavily within the narrative, every book also acts as a hook to pull readers into other titles in the series. The end result is that every book in the series acts like a first book, pulling in new readership and growing the series as a whole. BUT, because each book also helps advance the overall world of the series and sometimes even advances an overarching meta plot (as happens in the freakishly successful Immortals After Dark PNR series), each new release also acts like a sequential novel in a long running series, carrying reader investment along through multiple titles as they frantically read to see where things will go.

This truly is the best of both worlds! New readers are courted and enter with each new launch as if it was a book 1 while existing readers swarm to every new release the moment it comes out like it's the latest episode in a long running series. Because of this powerful synergy, these series can and do run crazy long--we're talking dozens of books or more--achieving lengths that few SFF writers would dare for, or be justified in even attempting.

With multiple entry points, people come in and then spider down the series's back-list growing the whole series to boot, creating some powerful sales mojo.

Just look at that monster! I flipped the retention rates to be modestly positive and behold: total earnings are double that of the traditional example. That's insane! The ladies who have the skills to do this are raking it in, lemme tell ya.

I call these "episodic series" since, like every episode of Law and Order, every novel can technically stand alone while also functioning as a new entry in a longer plot. They also seem to be a Romance phenomenon due to that genre's requirement for HEA endings. The Dresden Files is the closest thing I can think of to doing the same thing in SFF, but it's not truly an episodic series since, while each new novel has an enclosed plot, there's still a lot of sequential reading involved to actually understand what's going on. That said, though, I bet ya this math is the reason they stopped numbering the Dresden Files books. The publisher is trying to harness that Romance math by creating more entry points into Butcher's series. 

Sadly, I do not know if this kind of setup can be ever be truly duplicated in SFF. I've not heard of it if it has happened, and I suspect that it might rely tightly upon the unique nature of Romance readers and culture. It might also just be a catch-22: they can get away with episodic books because they've always had them. Seriously, this style of Romance writing goes back to the very beginning of the genre.

Sadly for the rest of us, other genres (with the exception of Mysteries, who do something similar by having one detective that solves a new case in each book) don't seem to be able to make the jump to this episodic style for whatever reason. Our readers just don't take to it as well. If they did, looking at the math above, I guarantee you we'd be up to our ears in episodic Fantasies, SF, and everything else.

Le sigh...

But enough pining for other people's sales mojo. Let's move on to what we do have!

Special Case #2 - Serials

SFF and other genres might not have access to the episodic series mojo in the same way Romance does, but there's still a way to have your cake and eat it too.

Normally, having a lot of books published as a long series involves a lot of risk and time investment, all of which can be deep-sixed by one bad book. But there is a way to dodge both the giant time investment of a standard series and to reduce the risk (or costs rather) of a mid-series failure, and it's called the serial. 

These beasts are pretty new (to our current marketplace, at least. The Victorians were all about 'em!) and things are kinda a wild west right now. There's not really a standard yet, but basically a serial is a long running story broken up into 20k to 40k (or smaller!) chunks that are tight, fast reads. If novels are movies, then series are episodes in a TV season. In fact, many serial authors actually adopt TV show structuring and language. They produce serials in "seasons" and call each installment an "episode"  to make sure readers understand what they're getting into. This is a very good idea since there is no force more terrifying than a reader who thought they were getting a novel and ended up with a serial instead.

Now, I don't have first hand or even second hand experience with serials. I don't read them and Rachel doesn't write them, so I have no way of knowing if it's a good way to structure a story. Today, I just want to comment upon the insane strengths of their math.

See, the scary truth of our current marketplace is that, well.. er... (I HATE to say this) shorter books don't really sell less well than longer ones.

This is likely why we've seen the length of a full novel creeping down. Why, in my day, 120k+ was a proper fantasy novel! Thrillers, Mysteries, and "Beach Books" were in the 90k range and novellas (hahaha) were 50-60k. These days, I keep hearing people talking about 70k novels or lower and I just want to shake my head. Maybe this is just my version of "you darned kids," but the fact is that novels are getting shorter because that's the way the money flows.

This is all simple economics, really. The best, most powerful way to grow as an author is to publish lots of books. If you can publish 4 books at 80k each per year, why should you publish two 180k books that year instead? (Commercially speaking, of course) The guy/gal who publishes 4 books a year will grow more than twice as fast as the author pushing 2 a year assuming that customer satisfaction remains equal.

"Customer satisfaction" is the sticking point. Despite being economically superior in every way, shorter books have a weakness in that they are not as popular with readers nor do they build as stable a fandom as longer books do. Speaking broadly, shorter books are just, well, a bit more forgettable than longer ones. This isn't because writers of short books aren't as talented as long form writers. They just have less room to work to work with. There are outliers of course, but for most writers, it's simply not possible to squeeze as much character development, complexity, and drama into 50k as you can into 100k.

Also, traditional publishing has taught readers over years to expect a certain amount of story in a book. If they get less than expected, they can easily feel cheated, even they paid a reduced rate for the title. This might change as readers adapt to the trend for shorter fiction, but right now at least, most readers have a very fixed idea of how much story a "novel" entails. Cheat them out of that, and it doesn't matter how good your short book is, you're going to get bad reviews. Even worse, you'll have readers who feel ripped off, and that's a BAAAAAAAD thing. 

This expectation is why successful serial writers adapt the language of television rather than novel series. A "novel" has a fixed definition in many people's minds, but an "episode" is something else entirely. By managing expectations successfully, many serial writers have figured out how to bridge both worlds. A 12 episode serial that has 40k word episodes is therefore 480k words long. That's the same word count (and risk) as a 4-book series of average length books. Except for the part where it sells and can be marketed like a 12-book series..... 

Boom baby!

And that's why we are suddenly seeing a revival of the serial despite the fact that readers famously hate serials. Despite the fact that many of the big serials have loads of nasty reviews. Despite people saying that they don't want to pay $2.99 x 12 to read the whole story or people saying that they hate the constant cliff hangers (one per episode!). OR People saying that the story they just paid for was too short. AND People feeling like they got conned into buying a short-story they though was a novel...

I could go on, but ya'll get the point. IMO these problems are all reader expectation and marketing issues. Over time, as people find and read more good serials and get used to the format, these things will smooth themselves out. There are already successful and well reviewed serials out there, so victory is clearly possible (and extremely lucrative).

Like I said, though, we have 0 personal experience with series. If you want to write one, my only real advice is to go do your research first. I wish there was more I could say, but we don't have a lot of experience here... yet ^_~.

Anyway, let's wrap up cause wow this post got long.

How Long Should Your Series Be?

Artistically? It should be whatever length is best to tell the story with. 

That said, the longer I do this job, the more I realize how flexible a good story idea can be. Often times, a long book is just one removed side character or plot-can-kicked-down-the-road away from being a normal sized book. Conversely, many stories have areas that can be gainfully explored and brought up to main plot level, providing extra distance if desired. You can fudge it, in other words.

But should you fudge it? Commercially, it depends on skill and interest. Are you good enough and interested enough in the story to write a long series? (Don't dismiss boredom! It's a major risk on multi-year projects.)

Longer series are riskier than shorter ones. It takes more skill and experience to properly structure and execute a long series, with tension management being only one of your concerns. However, I feel that the reliability of earning power and their marketing advantages make for tantalizing rewards.

Shorter series carry less risk and (often) a lower difficulty curve. They're also still perfectly commercially viable. There's nothing wrong with writing a 3-book series or even a stand alone! In the end though, it all comes back to the strategic level thinking I talked about last week. What do you need to write to get to where you are going? Think ahead! Look at where you will be if you do a 5-book vs a 3-book. Do you like that position? Does it set you up for the next series and where you want to go? These are serious considerations.

There's also the whole deal with smart risks. Corporations love sequels because they are such reliable earners. However, sequels are seldom break out hits. It takes a new idea to break out and become the next big thing. Publishing knows this, which is why the debut author is such a huge thing. They are always looking for that next big hit, and they know it doesn't come from a book 3.

What this means for your own career is something only you can decide, but I hope that I've helped arm you with enough information to make the choice a bit less murky. Again, there is no real right or wrong here. Strong as the math argument for a long series is, I really don't feel like this is a black and white issue. Life is messy and careers are complicated. Same goes for writing. Take your time, think and plan. Decide what's best for you and your writing! 

Thanks for Reading!

If there's any topics you'd like me or Rachel to talk about here on the blog, please feel free to leave them below. We're always working hard to find information that is useful to you. You can also just hit me up on Twitter, that works too! (@TravBach) Rachel's social media links are here as well if you want to get live updates! (Twitter/Facebook/Tumblr/Google+)

Thanks again for reading, and I'll see you all next week!

Sincerely,

-Travis