Book Math Tools

Book Break-Even Calculator

Add up what the book cost to produce, enter what you earn per copy, and see how many sales it takes to get your money back and how long that takes at your current sales and ad spend.

Total upfront cost
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Copies to break even
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Months to break even
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Profit after 12 months
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Copies a month to pay for ads
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How the break-even point is calculated

copies to break even = upfront costs ÷ royalty per copymonths to break even = upfront costs ÷ (copies per month × royalty − monthly ad spend)

The first number ignores time: it is simply how many sales pay back what you spent. The second adds your sales rate and ongoing ads. Both are rounded up, because half a copy doesn't pay anything. Profit after 12 months is twelve months of net income minus the upfront costs, so a negative figure means you are still in the red after a year.

Worked example: a paperback with no ads

A 250-page 6" x 9" paperback on Amazon.com costs $4.00 to print. At $14.99 it earns $4.99 per copy at the 60% rate. The author paid $350 for the cover, $900 for editing and $75 for formatting, $1,325.00 in total.

Worked example: an ebook with ads

A $4.99 ebook with a 2 MB file earns $3.28 per sale at 70% on Amazon.com. Costs were $400 for the cover and $1,500 for a developmental edit, $1,900.00 in total. It sells 80 copies a month and the author spends $150 a month on ads.

Making the numbers work

The fastest lever is usually cost, not sales. Many first books never sell a few hundred copies, so a $3,000 production budget can take years to earn back while a $600 one pays off in the first months. Spend on the cover and a proofread first, since readers judge both immediately; a full developmental edit pays off more on a series than on a one-off.

If you write in a series, judge the cost of book 1 against the whole series, not book 1 alone. A reader who finishes book 1 and buys the next three books is worth several times the first royalty. The series read-through calculator shows what each new reader is worth, which is the number to compare your cost per reader against.

Check the price too. On paperbacks, moving from $9.98 to $9.99 switches KDP's royalty from 50% to 60%, which can cut the copies needed by a fifth. Try both prices in the price change calculator.

Frequently asked questions

What costs should I include?

Everything you paid before the first sale: cover design, editing, proofreading, formatting, ISBNs if you bought your own, illustration, author copies you gave away, and any launch costs such as a paid newsletter promotion. Leave out ongoing ads; enter those as the monthly ad spend so the calculator can show how they change the timeline.

Which royalty per copy should I use?

Use what you actually keep per sale after KDP's cut and printing cost. The paperback royalty calculator and ebook royalty calculator give exact figures. If you sell both formats, use a blended figure: for example, if 70% of sales are ebooks at $3.28 and 30% are paperbacks at $4.99, the blend is 0.7 × 3.28 + 0.3 × 4.99 = $3.79.

How do Kindle Unlimited page reads fit in?

Convert them to sales. One full read of a book with a KENPC of 300 at $0.0045 per page is worth $1.35, so add your monthly KU earnings to the copies field as equivalent sales, or work out the earnings with the KENP calculator and divide by your royalty per copy.

Why does it say I never break even?

Your monthly ad spend is equal to or larger than the royalty from the copies you sell each month, so every month adds to the loss. Either the ads need to sell more copies, the bids need to come down, or the ads should stop. The break-even ACoS calculator shows the most you can spend per sale.

Sources

Rates last checked against KDP's help pages on 2026-10-16.

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