# Calculating readthrough on the Last Mayor series

Readthrough is a fascinating concept that may seem a little complex and alien at first, but is actually super obvious and essential to know when selling books in a series. You’ve probably heard Mark Dawson banging on about it. Maybe you’ve had a crack at calculating it.

It basically means – what percentage of people who read your first book in series go on to read the later books? I’ve had a go at this before, and came up with something like a 50% readthrough for my whole Last Mayor 9-book series. It’s important because it helps you determine the Cost of Sales you can bear when advertising book 1 in the series.

You calculate it by looking at sales from a given period. 10 copies of book 1 and 5 copies of book 2? That’s a 50% readthrough. 3 copies of book 9? That’s 30%. Factor in KU page reads, and you get a complete idea of how much money you can expect a single copy of book 1 to ultimately earn.

Yesterday I read Michael Cooper’s book My Facebook Ads Suck, and he went through this, and provided a handy Google Sheet that calculates Readthrough and total sales value. I did it a few different ways. All 2018. Jan 2019. The last 6 months. It was hard to get a clear idea, because I’ve variously done mass free giveaways, plus I have the boxset books 1-3 and 4-6, throwing things off.

I just ran a master calculation – not useful for getting the ultimate sales value of book 1, but more to know what my read through is. I add sales and reads for book 1 and books 1-3 boxset together – that’s step 1. Then I add book 4 and books 4-6 boxset together for step 2. Then books 7, 8, 9.

The readthrough number is disappointing. From step 1 to 2 it is 35%. Ouch. Michael Cooper says 50-60% is a good average readthrough. I’m well below. But OK, he makes compensation for 99-cent opening books – and these books were both very often at 99c. 99c readers are less likely to read the books they buy, and they pick up books less likely to really appeal to them in general. So maybe 35% is not so bad.

Then let’s take step 2 to step 3, into book 7. We’re down to 10% from step one. Again, not necessarily so bad given the 99-cent thing. But from books 4 and 4-6 to book 7, the book-over-book readthrough is 30%.

Crap. Two thirds of my readers who’ve already bought in to the series twice (ie – made purchases twice) don’t want to take it on to book 7! From there readthrough is 66% to book 8, then 55% to book 9, which is better, but yes – we’re down to much diminished numbers already.

So what’s going on? Forget the ultimate sale value – it’s probably around \$5-\$6 (more in a Facebook Ads post soon) – why am I getting such drop-off?

Let’s look at the books, and the reviews.

• Book 1 – 235 reviews, 4.5 star
• Book 2 – 40 reviews, 4.7 star
• Book 3 – 31 reviews, 4.2 star
• Book 4 – 40 reviews, 4.9 star
• Book 5 – 28 reviews, 5 star
• Book 6 – 21 reviews, 5 star
• Book 7 – 28 reviews, 4.8 star
• Book 8 – 18 reviews, 5 star
• Book 9 – 18 reviews, 5 star

Hmm, no real help here. We can clearly see total review numbers dropping off, which matches the sales readthrough calculation. It also makes sense that reviews get better as we get deeper – only the fans are still reading.

But why the drop off from Book 1 to 2? Hmm. Book 1 has great reviews. Readers like it. It’s true there is no cliffhanger – the book is resolved, so perhaps there is no big drive to readthrough? Maybe some people have just had enough of me and my writing style at this point?

Book 3 is a drop off in star rating – so maybe there are issues there? However, I remember when this used to be 3.9. I made numerous edits to speed the book up over a year ago, so now to see 4.2 seems a reflection of this. People like it better.

So why? It’s a mystery. I’d love readthrough to be way up there. It would make doing advertising a lot more rewarding. Maybe I will hire an editor to look at this in particular – why do people stop reading? Your thoughts welcome!