What two colors make cobalt blue?

Chromilla's watercolor recipe uses 3 tubes rather than two: 12 parts Ultramarine Blue, 5 parts Phthalo Blue and 3 parts Titanium White. Ultramarine Blue leads the mix. Chromilla's model predicts a 94% dry match against the target, scored against its own color model, not a measured paint-out.

What is the hex code for cobalt blue?

Chromilla uses #2E4C99 as the target for cobalt blue. The watercolor recipe is predicted to dry to about #1E4596.

Can I mix cobalt blue without black?

Yes. Chromilla's watercolor recipe uses no black: 12 parts Ultramarine Blue, 5 parts Phthalo Blue and 3 parts Titanium White.

How to Mix Cobalt Blue in Watercolor

Quick answer

To mix cobalt blue (#2E4C99) in watercolor, use 12 parts Ultramarine Blue, 5 parts Phthalo Blue and 3 parts Titanium White. Chromilla's model predicts a 94% dry match against the target, scored against its own color model, not a measured paint-out. Chromilla is a web-based paint color mixer that turns any color, from a photo, the camera or a hex code, into exact paint-tube ratios for acrylic, oil and watercolor, using Kubelka-Munk pigment mixing and aiming at the color after it dries.

Adjust for my paints

Target

Cobalt Blue

#2E4C99

Predicted dry result

94% match when dry

Mix to #224BA1 while wet. It dries to about #1E4596.

Cobalt Blue in watercolor: tube ratios, and ml for a 100 ml batch
Paint	Pigment	Parts	Share	100 ml batch
Ultramarine Blue	PB29	12	59%	59 ml
Phthalo Blue	PB15	5	26%	26 ml
Titanium White	PW6	3	15%	15 ml

How we calculated this: Kubelka-Munk pigment mixing, then a per-medium dry shift, scored with CIEDE2000. Method and accuracy benchmark. Last checked August 2026.

Terms used here: Tinting strength, Dry shift, Kubelka-Munk, Delta E (dE2000), Pigment code, Gamut.

A pure, mid-value blue. Neutral leaning (neither warm nor cool). This guide gives you the pigment ratios that land on #2E4C99 in watercolor, using the same solver that powers the Chromilla mixer.

Pigment recipe

Checked August 2026

Ratios calibrated for watercolor. Start with the dominant pigment, add the modifiers in the order below, and adjust in 5% steps to your target swatch.

1. Ultramarine Blue
PB29
59%
2. Phthalo Blue
PB15
26%
3. Titanium White
PW6
15%

What colors make Cobalt Blue?

Ultramarine Blue, Phthalo Blue, and Titanium White, in roughly a 59:26:15 ratio.

How to make Cobalt Blue in watercolor

Start with Ultramarine Blue at about 59% as your watercolor base, then work in Phthalo Blue and Titanium White in the order above. Adjust in 5% steps until the swatch reads #2E4C99.

Why mix Cobalt Blue instead of buying it

Mixing Cobalt Blue yourself lets you approximate an expensive or hard to find tube from pigments you already own, match Cobalt Blue across paint brands whose factory tubes differ, and rebuild the exact color when you run out mid painting. The recipe above is the working starting point.

Common mistakes

That pigment is a very strong tinter, add it a touch at a time or it will swallow the mix. White cools and chalks a mix as you add it, so tint in small steps and stop before it goes pastel.

Variations on Cobalt Blue

Each variation is its own target (lighter and darker move OKLCH lightness by 0.08; warmer and cooler turn the hue 12 degrees toward red or blue), solved fresh.

Lighter Cobalt Blue

#4364B3

7 parts Ultramarine Blue, 3 parts Titanium White and 1 part Phthalo Blue. Chromilla's model predicts a 93% dry match against the target, scored against its own color model, not a measured paint-out.

Darker Cobalt Blue

#1A3580

8 parts Ultramarine Blue, 4 parts Viridian Green and 1 part Phthalo Blue. Chromilla's model predicts a 96% dry match against the target, scored against its own color model, not a measured paint-out.

Warmer Cobalt Blue

#424698

85% Ultramarine Blue, 12% Titanium White and 3% Alizarin Crimson. Chromilla's model predicts a 92% dry match against the target, scored against its own color model, not a measured paint-out.

Cooler Cobalt Blue

#2B4D99

3 parts Ultramarine Blue, 2 parts Phthalo Blue and 1 part Titanium White. Chromilla's model predicts a 93% dry match against the target, scored against its own color model, not a measured paint-out.

Cobalt Blue questions

What two colors make cobalt blue?: Chromilla's watercolor recipe uses 3 tubes rather than two: 12 parts Ultramarine Blue, 5 parts Phthalo Blue and 3 parts Titanium White. Ultramarine Blue leads the mix. Chromilla's model predicts a 94% dry match against the target, scored against its own color model, not a measured paint-out.
How do you make cobalt blue paint lighter without losing the hue?: Re-balance the mix instead of only adding white. For a lighter cobalt blue (#4364B3) in watercolor, Chromilla mixes 7 parts Ultramarine Blue, 3 parts Titanium White and 1 part Phthalo Blue. Chromilla's model predicts a 93% dry match against the target, scored against its own color model, not a measured paint-out.
What is the hex code for cobalt blue?: Chromilla uses #2E4C99 as the target for cobalt blue. The watercolor recipe is predicted to dry to about #1E4596.
Can I mix cobalt blue without black?: Yes. Chromilla's watercolor recipe uses no black: 12 parts Ultramarine Blue, 5 parts Phthalo Blue and 3 parts Titanium White.

Cobalt Blue in other mediums

Cobalt Blue in Acrylic: 12 parts Ultramarine Blue, 5 parts Phthalo Blue and 3 parts Titanium White, predicted 93% dry match by Chromilla's color model.
Cobalt Blue in Oil: 12 parts Ultramarine Blue, 5 parts Phthalo Blue and 3 parts Titanium White, predicted 96% dry match by Chromilla's color model.

Get this recipe for your paint brand

Open the live mixer with Cobalt Blue + watercolor pre-loaded and calibrate to your tubes.

Open in mixer

Technique guides for this color

Related mixing guides

Pigment mixing is subtractive, so small ratio changes matter. The mixer refines this recipe to your brand and updates on the fly.