For your readers
Put the calculator on your site.
If you already write about money and KDP, borrow the math. The widget is free. It links back. Join the partner program if you also want those clicks to pay you.
<iframe src="https://www.dreamauthors.com/embed/royalty.php" title="KDP royalty calculator" style="width:100%;min-height:640px;border:0;border-radius:12px"></iframe> <p style="font:12px/1.4 sans-serif"><a href="https://www.dreamauthors.com/">Royalty math by Dream Authors</a></p>