30-page coloring book on letter paper: 3:4 or 4:5, $0.74 to $1.50

A 30-page coloring book printed on US letter paper (8.5 by 11 inches) needs images with a width to height ratio of 0.773, and Sume's image models list 3:4 (0.75) and 4:5 (0.80) but not 17:22. Generate at 4:5 and trim 3.4 percent of the width, or at 3:4 and trim 2.9 percent of the height. Thirty pages cost between $0.74 and $1.50 across the rows below, as of 2026-10-09.

The trim is small enough to plan for in the prompt: keep the drawing away from the outer 5 percent of the page. Coloring pages need a margin anyway, so the crop costs nothing.

The ratios and the totals

The ratio of letter paper is 8.5 divided by 11, which is 0.7727. A 4:5 image is 0.8, so cutting the width to 96.6 percent of its original value matches the paper. A 3:4 image is 0.75, so cutting the height to 97.1 percent does the same. Grok Image and Imagen 4 Fast list 3:4 but not 4:5; the other rows list both.

Make the pages usable

Ask for line art in the prompt: black outline only, white background, no shading, no grey fills. Check the first page at print size before running the other 29, because a model that adds grey tone makes a page that cannot be colored cleanly.

Recraft V4 returns WebP only on Sume, and not every print tool opens WebP, so convert it to PNG in your own pipeline. If you want to keep a page's outline sharp, avoid JPEG for the final file.

Trim in code

Pillow trims the extra width from a 4:5 render. The script centers the crop and resizes to a 300 dpi letter page, 2550 by 3300 pixels. It takes a local file, so download the Sume result URL first.

from PIL import Image

TARGET = (2550, 3300)  # 8.5 x 11 inches at 300 dpi

def fit_letter(path_in, path_out):
    img = Image.open(path_in).convert("L")
    w, h = img.size
    new_w = min(w, round(h * TARGET[0] / TARGET[1]))
    left = (w - new_w) // 2
    page = img.crop((left, 0, left + new_w, h))
    page.resize(TARGET, Image.LANCZOS).save(path_out, dpi=(300, 300))

fit_letter("page-01.png", "page-01-letter.png")

Page order and covers

A book needs a cover and a title page as well, so budget 32 images for a 30 page interior plus a cover and a back. At the GPT Image 2.5 low price that is 32 times $0.02475, or $0.79, and at the Recraft price it is $1.60.

Generate every page from one shared style sentence, and put only the subject in the part that changes. Keep the line weight words the same on every page, such as thick clean outline, so the book looks like one set. Review all pages in a grid before you print, and regenerate the two or three that break the style.

A note on resolution

A 1K render stretched to 2550 by 3300 pixels is an upscale of about 2.5 times, so the lines will look soft at print size. If the lines matter, use a model with a higher tier or Sume's image upscale at $0.20 per page, which would add $6.00 to 30 pages.