Quick answer
Mosaci Studio sets a color-by-number page anywhere from 4 to 23 colors, with 12 as the default. Color count and cell size together decide how many numbers a colorist must track and how many regions they fill. Younger children usually suit 4 to 6 colors, and experienced colorists 15 to 20.
What the Color Count Setting Does
On the color patterns (Square, Circle, Diamond, Hexagon, Puzzle, Islamic, Fish Scale and Trapezoid), the converter reduces your image to at most the number of colors you choose and gives each one a code on the key: the digits 1–9, then letters from A. At the 20-color maximum the key runs 1–9 and A–K.
The monochrome mark styles work differently. Square Mark uses a dot plus five marks, and Hexagon Mark a dot plus six marks, so they work from fixed tone levels and the color-count setting does not apply to them. If you want a single pen and no palette, see monochrome color by number.
| Setting | Range in the tool | What it changes |
|---|---|---|
| Colors (color patterns only) | 4 to 23, default 12 | How many different numbers appear on the page and in the key |
| Cell size | 12 to 36 | How large each cell is, and therefore how many cells the page has |
| Pattern | 8 color patterns, 2 mark styles | The cell shape and how the cells fit together |
Color Count, Cell Size and Region Count Are Different Things
Color count is how many distinct numbers there are. Cell size sets how many cells fill the page: smaller cells mean more of them, and more of the photo's detail survives. The two interact, which is why changing one can make a page feel easier or harder than you expected.
- Few colors, large cells: big, simple regions and a short key. Fast to finish.
- Few colors, small cells: many cells but only a handful of numbers, so the work is long yet repetitive.
- Many colors, large cells: a long key and coarse regions, which can look blotchy.
- Many colors, small cells: the most detail and the most effort: a long key and a lot of cells.
Photo conversion adds a third factor. A photo with soft gradients needs more colors before shading looks smooth, while a bold illustration with flat areas holds up on very few.
How Many Colors by Age and Skill Level
There is no tested threshold for any age. The ranges below are starting points to try in the live preview, built on how the settings behave: each extra color is one more number to find and one more shade to tell apart. Adjust from there until the preview looks like a page the colorist would enjoy finishing.
| Colorist | Colors to start with | Cell size | Why |
|---|---|---|---|
| Younger children | 4 to 6 | Toward the larger end | A short key and big regions keep the page finishable in one sitting |
| Older children and beginners | 7 to 10 | Mid-range | Enough colors to recognize the subject, still a key that fits in one glance |
| Adults new to color by number | 10 to 14, the default is 12 | Mid-range | Room for shading without a long key |
| Experienced colorists | 15 to 20 | Smaller | More shades and more regions for those who want a long project |
How More Colors Make a Page Harder
Each added color has two costs. The first is the key: with 20 colors the colorist is matching a number to a swatch from a list that runs 1–9 and A–K. The second is similar shades, because the converter splits tones into separate colors that can sit close together on the key. Two neighboring swatches that look almost the same are where mistakes happen.
Fewer colors do not always make a page easier to recognize. At the low end, faces and fine subjects flatten into patches, so a portrait that reads clearly at 12 colors can look like a map at 4. If the subject stops being recognizable in the preview, add colors before you shrink the cells.
Choosing Colors for a Coloring Book
A book is a set of pages, so consistency matters more than any single page. Mosaci applies one pattern, cell size and palette setting across a whole batch, which keeps a book's pages feeling like one product. Pick a count that suits your target colorist, check it on your hardest photo first, and then run the batch. For the full workflow, see how to create a color by number book for KDP and the coloring book generator.
A Quick Way to Decide
- Start at the default of 12 colors with a mid-range cell size.
- Open the preview and ask whether the subject is still recognizable.
- If it is blotchy or flat, add colors. If the key looks long, remove them.
- Print one page at final size and color a corner before committing to a whole set.
If a page still feels too hard or too plain after adjusting colors, how to make a color-by-number page more detailed and color-by-number difficulty levels cover the other levers, and the color-by-number generator lets you try each setting on your own image.
Printable quality checklist
- Start at the default of 12 colors with a mid-range cell size
- Check the preview: is the subject still recognizable
- Add colors if the page looks flat; remove them if the key looks long
- Use larger cells and fewer colors for younger children
- Apply one pattern, cell size and palette across a whole book
- Print one page at final size and color a corner before converting a set
Key takeaways
- Mosaci Studio sets a color-by-number page between 4 and 23 colors, with 12 as the default.
- Color count (how many numbers) and cell size (how many cells) are separate settings that combine into difficulty.
- Younger children usually do best with 4 to 6 colors; adults and beginners with 10 to 14; experienced colorists with 15 to 20.
- More colors mean a longer key and more near-identical shades, which is where coloring mistakes happen.
- The monochrome mark styles ignore the color-count setting and use fixed tone levels.
- Apply one palette setting across a whole book so its pages stay consistent.
Frequently asked questions
What is the best number of colors for a color-by-number page?
There is no single best number. In Mosaci Studio the range is 4 to 23 colors and the default is 12, which suits most pages. Use fewer colors for children and quick pages, and more for experienced colorists who want shading.
What is the maximum number of colors Mosaci can use on one page?
23. The color-count setting runs from 4 to 23 on the color patterns. The monochrome mark styles ignore it and use fixed tone levels: a dot plus five marks for Square Mark, and a dot plus six marks for Hexagon Mark.
Do more colors make a color-by-number page harder?
Yes, usually. Each added color is another number to find on the key and another shade to tell apart from its neighbors. More colors also tend to produce more small regions, so the page takes longer to finish.
How many colors should a child's color-by-number page have?
A reasonable starting point is 4 to 6 colors with larger cells, so the key is short and the regions are big. This is a starting point to check in the live preview, not a tested rule, and every child is different.
What is the difference between color count and cell size?
Color count is how many different numbers and shades the page uses. Cell size is how large each cell is, which sets how many cells the page has. A page can have few colors and many tiny cells, or many colors and large cells.
Does a bigger palette always look more realistic?
Not always. A larger palette can render smooth shading in a photo with soft gradients, but a bold illustration with flat areas looks fine on very few colors, and similar adjacent shades can make a page harder to color without making it look better.
Should every page in a coloring book use the same number of colors?
It helps. Applying one pattern, cell size and palette setting across the whole batch keeps a book consistent for the colorist. Test the setting on the hardest photo in the set before converting the rest.
How do I make a coloring page that needs only one pen?
Use one of the monochrome mark styles: Square Mark or Hexagon Mark. They turn tone into marks instead of colors, so the whole page can be completed with a single pen or pencil.
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Written by
Mosaci Studio TeamThe team behind Mosaci Studio
Mosaci Studio is built to help KDP publishers, Etsy sellers, and hobby artists turn photos into print-ready coloring pages without any design experience.
Published Sep 3, 2026 · Updated Oct 6, 2026