How many ARC readers do I need?
The short answer: about twice as many readers as the reviews you want, if your readers review at around 50%. The useful answer depends on two numbers you can estimate - how many invited readers will download, and how many of those will review - so here's how to work it out for your launch.
The formula
Readers to invite = reviews you want ÷ download rate ÷ review rate
- Download rate: the share of invited readers who download the copy. In one documented romantasy campaign it was 92% (520 of 564).Illene
- Review rate: the share of downloaders who post a review. The same campaign measured 50.6% after 12 days and 59.8% after six months.Illene
Example: you want 25 reviews by launch week, and expect a 92% download rate and a 50% review rate. 25 ÷ 0.92 ÷ 0.5 = 54.3, so invite 55 readers.
The table
Readers to invite, assuming 92% download. Pick the row for the reviews you want and the column closest to your readers' review rate.
| Reviews wanted | 40% review | 50% review | 60% review | 75% review |
|---|---|---|---|---|
| 10 | 28 | 22 | 19 | 15 |
| 25 | 68 | 55 | 46 | 37 |
| 50 | 136 | 109 | 91 | 73 |
| 100 | 272 | 218 | 182 | 145 |
Arithmetic only, rounded up. The 92% download rate comes from a single campaignIllene; yours may differ.
Which review rate to use
Use your own if you have it - the share of downloaded ARCs your readers reviewed last launch. If you don't, use a rate that matches where your readers come from:
| Reader source | Measured or published rate |
|---|---|
| Booksprout | 38.4% organic, 50% invited, in one campaign |
| Mixed sources, one romantasy launch | 50.6% at 12 days, 59.8% at six months |
| Hidden Gems | About 60% in one campaign; Hidden Gems publishes an average of over 80% |
| BookSirens | About 75% site-wide (their figure); 93% invited and 72% organic in one campaign |
Per-platform campaign figures from one documented launchIllene; BookSirens' site-wide rateBookSirens and Hidden Gems' averageHidden Gems are the platforms' own figures. More on what each number measures in ARC review rates: what the data says.
If you're unsure, plan on 50% and treat anything above it as a bonus. For a brand-new list of readers you've never worked with, 40% is safer. If you're starting that list from scratch, here's how to build an ARC team from zero.
How many reviews to aim for
That depends on genre. Romance launches often aim for 50 to 100 or more; business books are better served by 10 to 25 from credible names. Our ARC playbook by genre has working targets for each category.
Three things that change the number
- The deadline. Reviews keep arriving after launch. If you're counting reviews by launch week, use the lower rate; by month six, the higher one.
- Reminders. A reminder halfway through the reading window and another a few days before launch bring back readers who meant to review and forgot. Our reminder email templatescover the wording.
- Who you invite. Readers you invited yourself reviewed at 93% against 72% for readers who requested the book, on the same platform in the same campaign.Illene Readers with a review history beat strangers.
Needing fewer readers every launch
The formula has one number you control over time: the review rate. If you track which readers review and invite them first next time, your rate goes up and the number of copies you need goes down. A team that reviews at 75% needs about half as many readers as one at 40%.
That's what ArcRoster keeps track of: each reader's review rate across your launches, shown as a reliability tier, so you can fill the next campaign from your Trusted and Reliable readers before anyone else. See also how to tell which ARC readers actually review.
Sources
- Brutally Honest ARC Campaign Results - Susan Illene, September 2025.Field report
One romantasy launch (Oaths & Vengeance), six-week window, 622 requests across five platforms plus a direct list. A single campaign, not an industry average.
- What is the expected review rate? - BookSirens Support, Checked July 2026.Vendor-reported
BookSirens' own site-wide figure. They state explicitly that individual books range from above 90% to below 50%.