Free KDP Tools You Can Embed

Two small tools that solve the two questions every self-publisher hits before upload — and both are free to drop into your own blog post with two lines of HTML.

The spine calculator turns a page count and paper choice into KDP's exact spine width and full-wrap size; the thumbnail test shows whether your cover's title still reads at Amazon's search-grid size. Neither needs an account, and covers you drop into the thumbnail test never leave your browser.

KDP spine width & full-wrap calculator

Enter your page count, paper (white/cream) and trim size; it returns KDP's spine width in inches, mm and pixels plus the full-wrap cover size (front + spine + back + bleed) — the exact numbers KDP's template generator uses.

Embed this calculator on your site

Copy the two lines below — the calculator works as-is in your blog post, with a small Veritas Canvas credit underneath.

<div data-veritas-spine data-lang="en"></div>
<script src="https://www.veritascanvas.com/veritas-spine-widget.js" defer></script>

Amazon thumbnail readability test

Upload (or drag) a cover and see it at Amazon's real thumbnail sizes side by side, plus grayscale and squint tests. If the title doesn't read at stamp size, it doesn't sell — this catches it before you upload.

Embed this thumbnail test on your site

Copy the two lines below — the test works as-is in your blog post. Your readers' covers never leave their browser (nothing is uploaded), with a small Veritas Canvas credit underneath.

<div data-veritas-thumb data-lang="en"></div>
<script src="https://www.veritascanvas.com/veritas-thumb-widget.js" defer></script>