Gutterproof sets up your pages with the right trim, bleed and a gutter sized to your page count, then checks every page for anything KDP will flag, before you export.
Not built yet. We're gauging interest before we build it. Early sign-ups get founder pricing.
KDP's inside margin grows with your page count: 0.375″ up to 150 pages, then 0.5″, 0.625″, 0.75″ and 0.875″ for the thickest books. Canva doesn't know your page count, doesn't mirror left and right pages, and never warns you. You find out after upload.
Add pages to a coloring or puzzle book and you cross into a wider gutter band without noticing.
Page numbers, borders and frames that look fine on screen sit inside KDP's no-go zone.
With bleed, the page is 0.125″ wider and 0.25″ taller than the trim. Easy to get backwards.
Trim size, page count, bleed or no bleed.
Correct page size, with left and right margin guides mirrored and the gutter set for your page count.
One click scans each page against KDP's minimums.
A list of problems with the page and element, so you fix them before KDP sees them.
Built for coloring books, journals, planners, logbooks, puzzle books and picture books designed in Canva. Paperback first, hardcover next.
| Page count | Inside (gutter) | Outside, no bleed | Outside, with bleed |
|---|---|---|---|
| 24–150 | 0.375″ | 0.25″ | 0.375″ |
| 151–300 | 0.5″ | 0.25″ | 0.375″ |
| 301–500 | 0.625″ | 0.25″ | 0.375″ |
| 501–700 | 0.75″ | 0.25″ | 0.375″ |
| 701–828 | 0.875″ | 0.25″ | 0.375″ |
Source: KDP Help, “Set Trim Size, Bleed, and Margins”. Minimums only; a little extra is safer.
We'll only build Gutterproof if enough people want it. Join the waitlist and you'll get:
No spam. We'll email you when the beta opens, and you can unsubscribe in one click.
Not yet. We build it only if enough people sign up and want to pay for it. The waitlist is how we find out.
That's the plan. Every Canva app goes through Canva's review before it's listed, so the timing depends partly on them.
No. KDP still reviews your file. Gutterproof catches the common problems earlier, inside Canva, so the previewer has less to complain about.
Gutterproof is for interiors. Covers have their own tools.
Gridmoss, a small independent studio that builds focused tools for people who make and sell things online. Questions: hello@getgridmoss.com.