How to use the Paint Mixing Calculator
- Set the target color. Type a HEX code, use the swatch to open your color picker, or drop a reference photo onto Or sample it from a photo and click the spot you want to match. The photo stays on your device, and each click averages a 5 × 5 pixel patch so a single noisy pixel can’t throw the target off.
- Tick the paints you own. The list holds 24 common artist pigments with their Colour Index codes. Use the presets — Split-primary set, Zorn palette, All 24 — or tick your own; your choice is remembered in this browser.
- Choose the recipe size. Up to 2 paints gives the simplest mixes; Up to 3 paints gets closer to tricky muted colors.
- Read the recipe. The best mix appears as parts, largest first — for example 6 : 2 : 1½ — with each paint’s share by volume, the simulated mix next to your target, and a ΔE score that says how far apart they are. Alternatives below show other routes to the same color; press Show to swap one in.
- Copy and test. Copy recipe puts the full mix, with pigment codes, on your clipboard. Mix a small batch, let it dry, and compare.
Why paint doesn’t mix like pixels
On a screen, colors add light. Paint works the other way round: every pigment absorbs part of the spectrum, and a mixture absorbs what each of its ingredients absorbs. That’s why the digital average of cadmium yellow #F6BC12 and ultramarine #2A3B9E is a drab tan, #907C58, while the same two paints on a palette give a green. Yellow reflects the middle and long wavelengths, ultramarine reflects the short ones with a tail into the blue-greens, and the only light both let through is green.
This calculator simulates that with the Kubelka–Munk model, the standard theory for opaque paint layers. Each pigment gets a smooth reflectance curve across 36 wavelengths, from 380 to 730 nanometers in 10 nm steps, fitted so it reproduces the pigment’s screen color. At every wavelength the reflectance R becomes an absorption-to-scattering ratio, K/S = (1 − R)² ÷ 2R. Mixing averages those ratios by concentration, and the mixture’s reflectance comes back as R = 1 + K/S − √((K/S)² + 2·K/S). The resulting spectrum is converted to color with an analytic fit of the CIE 1931 standard observer.
Pigments also differ wildly in tinting strength — a speck of phthalo blue overwhelms a spoonful of white, while cobalt blue barely makes a dent — so each paint carries a relative strength factor. The solver tries every single paint, every pair and every trio from your list, searches the ratios continuously, then rounds them to parts you can actually measure (½, 1, 1½, 2 … 50) and keeps whichever rounding stays closest. Recipes with fewer paints and less extreme ratios win ties.
Classic mixes, simulated
| Recipe | Simulated result | What you’d expect at the easel |
|---|---|---|
| 3 Cadmium Yellow : 1 Ultramarine Blue | #5E7649 |
A soft olive green, never as bright as a tube green |
| 3 Hansa Yellow Light : 1 Phthalo Blue | #195F5F |
A deep, cool blue-green; phthalo dominates fast |
| 1 Ultramarine Blue : 1 Burnt Sienna | #474038 |
The classic warm near-black for shadows |
| same + 4 Titanium White | #736A60 |
A useful warm gray for skies and stone |
| 1 Alizarin Crimson : 1 Ultramarine Blue | #482F46 |
A dark violet; tint it with white to see the hue |
| 4 Yellow Ochre : 1 Ivory Black | #403B31 |
A dark olive — black really does push yellows toward green |
| 1 Phthalo Blue : 10 Titanium White | #4381C6 |
Still a strong mid blue |
| 1 Ultramarine Blue : 10 Titanium White | #81A1DB |
Already a pale periwinkle — far weaker than phthalo |
The last two rows show the strength gap in numbers: at the same 1 : 10 dilution, phthalo stays a full mid-tone while ultramarine is close to a pastel.
How close is close enough?
The ΔE figure is the CIEDE2000 color difference between your target and the simulated mix. Below 1, most people can’t see a difference even side by side. From 1 to 2 it is visible only when the two touch. From 2 to 5 it’s a near miss you can fix by eye with a touch of one of the recipe’s paints. Above 10, the target is outside what your paints can reach — typically a color more saturated than any mixture of them. Whenever the best match is 5 or worse and some paints are unticked, the calculator also names the missing tube that would help most.
Treat every recipe as a starting point. The pigment colors here are approximations of typical artist-grade paints; real tubes vary by brand, binder, grade and batch, and the model knows nothing about glazing, texture or how thickly you paint.
Tips from practice
Add the dark to the light, never the other way. Start with the largest part — usually the white or the light yellow — and work the strong pigment in a little at a time. It takes a mountain of white to rescue a mix that got too much phthalo.
Mix more than you need. Remixing a color halfway through a passage almost never lands on the same value. For a background, mix at least a third more than you expect to use.
Judge your swatch dry. Acrylics usually dry a shade darker, and gouache and watercolor can shift noticeably as they dry. Paint a test patch, let it dry fully, then compare it with the target.
Learn a limited palette first. Tick the Zorn palette — yellow ochre, cadmium red light, ivory black and white — and see how many targets land within ΔE 5. Its range is narrow but every mix harmonizes, which is why it is a favorite for portrait practice.
Build a target palette, then mix it. Pull five or six colors from your reference with the Image to Palette Extractor and run each through this calculator before you squeeze out a single tube.