Digital books have no printing cost, which leads a lot of first-time publishers to assume the royalty question is simple. It is not, because the higher of the two rates Kindle offers is fenced in by a price band and carries a per-megabyte delivery deduction, so the best-paying choice changes depending on both what you charge and how heavy your file is.
This calculator runs both rates side by side for the price you enter. It applies the lower rate to the full list price with nothing deducted, applies the higher rate only where the price falls inside the eligible band, subtracts delivery based on the file size and marketplace you choose, and shows the resulting per-sale figure alongside an effective percentage of cover price.
Worked example, using this calculator on a 2 MB file in the US store. At 4.99 the higher rate leaves 3.19 a copy after 0.30 of delivery, against 1.75 on the lower rate. At 9.99 it leaves 6.69. Move the price to 10.99 and eligibility for the higher rate is lost entirely, so the same book drops to 3.85 — one dollar of extra list price cut the royalty nearly in half.
Because delivery is deducted from it and not from the lower rate. The charge scales with file size, so a heavily illustrated book can lose enough per copy that the smaller percentage of an undiminished price comes out ahead.
A per-megabyte cost applied to each copy sold under the higher rate, priced in the local currency of the store. This calculator holds a separate figure for every marketplace, which is why the same book returns different net royalties in different stores.
The converted file as Kindle stores it, which is usually dominated by images rather than text. Prose adds very little; a single uncompressed cover can add several megabytes on its own, and that is what the deduction is calculated against.