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How To Make Sky Blue Colour To Match Real Sky (6 Blue Tested)

Sky is blue, roses are red, we all know that byheart. But what is that sky blue exactly?

There is no single answer. Have you ever tried to find and match all the pieces of the sky in a puzzle?

There are actually a few colors: darker blues on the top and paler blue at the horizon line, almost white. So how to make sky blue colour that will match realistic sky?

Sky blue color can be mixed with ultramarine blue, Phthalo blue or Cobalt blue and titanium white. To make dark blue color add Phthalo blue or burnt umber. To mute the sky blue color add tiny dot of yellow or magenta.

How To Make Sky Blue Colour

With so many blue paints available let’s see how to make sky blue colour that will perfectly match a photo or sky color on a plein air painting.

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Why sky is blue? A bit of science

How To Make Sky Blue Colour
Beautiful mount Fuji and blue sky of Japan (may, 2023)

Why actually the sky is blue?

The sunlight is just white but we know for fact that we see the blue sky!

The atmosphere of our planet acts like a prism and the white sunlight gets scattered everywhere.

Blue light happens to be scattered more than any other color lights, have the smaller waves and it travels faster. Hence, the sky is blue 🙂 (Source)

There are colors that have strong collective associations – what we call memory colors: sky blue is one of them.

Different blue colors

If we will collect all blue paint tubes we will find lots of shades of blue:

  • Ultramarine blue,
  • Prussian blue,
  • Phthalo blue (green and red),
  • Primary Cyan,
  • Cobalt Blue,
  • Cerulean Blue are the most common ones.

But there are also turquoise blues, Light Blue and many more.

How To Make Sky Blue Color

Some brands name their colors Sky blue but even they don’t seem to find a middle ground as all the colors are simply very different:

How To Make Sky Blue Colour
sky blue colors on the market

Artists claim that none of them can substitute the true sky blue, first because the sunlight interferes with our subjective perception but also because the sky has also different shades and tints within, including…yellow and magenta!

There are also different skies: summer sky, winter sky, bright day, cloudy day, different seasons and so on.

Read also: What do Blue and Brown make? Testing 8 Shades of Blue & 6 Brown

How To Make Sky Blue Colour – Tips upfront

  • Ultramarine, Phthalo blue (greenish blue) and Cobalt Blue works best to make sky color.
    • bright, saturated clear blue sky – cobalt blue or cerulean and lots of titanium white make decent sky blue. Add ivory black or cadmium orange to dull it.
    • If the sky looks a bit purple I’d use Prussian blue.
    • Ultramarine and Phthalo work well even without white for darker blue color.
    • for lighter areas of the sky – Cobalt blue with a lot of white.
    • you can mix Ultramarine with primary cyan, cobalt blue and white to mix sky blue
    • for cloudy sky use Phthalo, Ultramarine or Cobalt blue with a touch of Yellow or Magenta.
  • Prussian blue doesn’t really work for mixing sky blue (it looks too lavender-ish to me when mixed with white).
  • indanthrene blue makes a really beautiful sky blue but it is a very rare pigment (it won’t be in any sets) and can be expensive.
  • I mostly use Titanium white but I know some pros prefer zinc white.
  • For darker sky try darker cobalt blue or ultramarine thinned with grey or titanium white.
  • generic sky blue in paint is always some blue paint with white.

I’ve made a video of my testing process:

I’m using in this test:

How to make sky blue with Ultramarine blue?

In each test I started with smaller amount of white and continued to increase it.

On the RIGHT is the least amount of white, on the left – the most white.

Ultramarine + Titamium White = darker Sky Blue

How to make sky blue with ultramarine blue

Ultramarine blue may seem purple-red-ish but not as much as Prussian blue and it stays very blue, intense color for bright sky.

Straight from the tube or with a little bit of white it can match deep sky blue color and darker areas of the sky.

How to make sky blue with ultramarine blue to match the photo

But it may appear lighted on thinner and tinted paper. I just tested out of curiosity on grey pastel paper and you can see that Ultramarine seems lighter here, yet matches sky color perfectly with some white.

How to make sky blue with Ultramarine blue

How to make sky blue with Phthalo blue?

Phthalo Blue comes in professional acrylic paint in 2 shades: green and red shade.

How to make sky blue with Phthalo blue?

I mostly use green Phthalo blue. Phthalo blue mixed with white makes nice sky blue.

How to make sky blue with Phthalo blue

But to matchthe real sky you may need to neutralize it with a tiny amount of Quinacridone Magenta. If you don’t have Magenta use Alizarin Crimson.

From left to right: Phthalo blue with Yellow, with Magenta, with just White

When I tried to match darker sky, Phthalo blue with a bit of magenta and white paint worked the best.

How to make sky blue colour with Phthalo blue

I believe both Phthalo and Ultramarine blue are great to make sky blue color with good amount of white and dot of Magenta for Phthalo blue.

You can even try to mix Phthalo and Ultramarine, as they may neutralize each other a little bit and then gradually add white to make sky blue.

Read the full guide on color mixing: How To Mix Acrylic Paint? – Your Complete Color Mixing Guide

How to make sky blue from Cobalt blue

Cobalt Blue mixed with white make great lighter sky blue color. Adding more white you can create sky blue color that matches the sky near the horizon.

How to make sky blue from Cobalt blue

In my tests, adding magenta or yellow wasn’t necessary when you mix sky color with Cobalt blue, but I also need to say that I had a tube of cheaper and paler Cobalt Blue than I know Liquitex has.

How to make sky blue from Cobalt blue

How to mix sky blue color with other shades of blue

I’ve also tested Cerulean and Primary Cyan Blue and to my liking they were too bright to match the natural sky colour.

However, if you are not matching sky from a picture, you may use Cerulean or Primary Cyan Blue mixed with white to make a very bright light blue.

How to make sky blue with cerulean blue

Adding Magenta and Yellow will again help to dull Cerulean Blue down for cloudy sky or darker areas of the sky.

Primary Cyan mixed with a lot of white makes very bright light blue.

How to make sky blue with primary cyan

I wouldn’t use Prussian Blue for making sky color – unless it is a darker area and maybe a seascape. For summer sky it feels lavender to me, and I didn’t go with it.

How to make sky blue with prussian blue

How to make sky color with 2 blue colors

To mix sky color blue that matches real sky you can mix Ultramarine Blue with lighter Cobalt blue or Prymary Cyan – they will balance each other and make harmonious sky color.

How to make sky color with 2 blue colors

I’ve come to this conclusion when I was trying to match a medium, neutral sky blue and I think that mix of Cobalt Blue and Ultramarine blue hasthe most potential.

I would even add a tiny bit of Magenta (but it will all depend on the lights on your photo or sky).

Prumaru Cyan mixed with Ultramarine and some white helps to match dark sky blue:

Mixing the Color of the Darker Part of a Blue Sky

Mix Ultramarine Blue or Phthalo Blue and Titanium White to match the darker sky color.

I also tested and find out that adding Yellow to Phthalo blue or Magenta to Ultramarine blue can help create darker sky blue color.

Yellow helps make a color duller, but if you add too much it will go green. Magenta leads toward purple sky which is very natural for some darker sky areas.

Mixing the Color of the Darker Part of a Blue Sky

If you feel like you’ve added way too much yellow or magenta, don’t worry, as long as the paint is still wet we can fix it – add more ultramarine blue and white and it will be ok.

Mixing the Color of the Lightest Part of a Blue Sky

The sky color is very light near the horizon, almost white, it rarely has any red or purple to it.

I find Cobalt Blue mixed with a generous about if white make the exact shade of the lightest blue sky.

Test different paper/canvas background

When you are trying to match sky color, it is also important to keep in mind that painting support (paper or canvas) and its color will affect the result.

I was testing the colors on watercolor paper of natural white color, but then I also tested Ultramarine blue on grey tinted thinner paper and you can see the difference:

Colors on white background will naturally appear brighter, they will pop. On the grey paper, Ultramarine almost looks lighter, duller, matter.

You should test it on canvas as well and have a few backup color mixes when you work.

If you are doing a plein air painting, not only the color of your background will matter, but also the sunlight. It will affect how you perceive the colors. The best way to paint sky outside is to facing away from the sun.


Which Colour mix makes sky blue?

You can make Sky blue color by mixing Ultramarine blue or Cobalt blue with generous amount of titanium white. 

How to make light blue colour by mixing two colours?

Light blue color can be made by mixing cobalt blue, cerulean blue or primary cyan with lots of white.

What color is close to sky blue?

Cyan, Cerulean Blue, Cobalt Blue and Ultramarine paint colors are close to natural sky color blue.

As you can see there are multiple options and room for experiments when it comes to matching natural colours, such as sky.

To create the beautiful blue color of the sky in your paintings, you can follow a few simple steps. Experiment with colors like Ultramarine,Cobalt, Phthalo Blue, Cerulean Blue and Cyan, which are similar to the sky’s blue.

Mix these colors with a bit of white to make them look more like the sky.

Remember, the sky’s color changes throughout the day and in different weather, so feel free to adjust the mix to match the mood you want in your artwork by adding Magenta, Yellow or even mixing the blues between each other.

I’m sure learning how to make the sky blue color will make your art look more realistic and captivating. Just have fun trying out different mixes and let the sky be your inspiration!