About Color Blind Simulator
Color Blind Simulator shows what a colour looks like to someone with a form of colour vision deficiency. Pick a colour and a type, and the tool applies a fixed transformation to the red, green and blue channels, returning the result as an uppercase hex value.
Three types are offered: protanopia for red-blindness, deuteranopia for green-blindness and tritanopia for blue-blindness. Each uses a different linear matrix, and the result is a single transformed colour - the sample indigo under protanopia comes back as a muted purple. A neutral grey passes through unchanged, because the matrices preserve equal channels.
The simulation is a useful first check for accessibility, but it is an approximation. It transforms one colour at a time using simple matrices with no severity setting, so it cannot reflect the many degrees of colour vision deficiency or the rarer forms. There is no image or palette upload and no before-and-after view, so testing a whole design means converting colours one at a time.
How to use Color Blind Simulator
- 1 Pick the colour you want to test in the Color field.
- 2 Choose a deficiency type - protanopia, deuteranopia or tritanopia.
- 3 Run the tool to read the colour as it appears under that deficiency.
Frequently asked questions
What do the three types mean?
Protanopia is red-blindness, deuteranopia is green-blindness and tritanopia is blue-blindness. Each applies a different matrix to the colour channels to approximate the corresponding deficiency.
Why did a grey stay exactly the same?
The matrices preserve equal red, green and blue channels, so a neutral grey such as #808080 passes through unchanged. Only colours with uneven channels are visibly shifted.
Is this an accurate simulation?
It is an approximation using simple linear matrices and a single severity. It is useful as a first check but is not clinically accurate, and it cannot model the many degrees and rare forms of colour vision deficiency.
Can I test a whole image or palette?
No. Only one colour is transformed at a time, with no image upload and no before-and-after view. To test a design you would convert its colours individually.
Free, online, and private
Free to use
Color Blind Simulator is completely free. There is no account to create, no login, and no hidden charge or usage limit.
Runs online in your browser
It is a free online tool that runs entirely in your browser. Nothing to download or install — open the page and start using it right away.
Your data stays private
All processing happens locally on your device. Your input is never uploaded, stored, or tracked, so it never leaves your browser.
How Color Blind Simulator behaves in detail
These are the specifics of this implementation — the exact ranges, defaults and fixed settings you are working with.
| Parameter | Value |
|---|---|
| Input | a Color picker starting at #4F46E5 and a Type selector with three choices |
| Types | protanopia for red-blindness, deuteranopia for green-blindness and tritanopia for blue-blindness |
| Output | a single transformed colour returned as an uppercase hex value |
| Mechanism | each type applies a fixed linear matrix to the red, green and blue channels |
| Default | the sample colour under protanopia reads #4B4BBF |
| Neutrality | a neutral grey such as #808080 passes through unchanged, since the matrices preserve equal channels |
Compiled from the implementation of this tool and checked against it by itoolnet.
What Color Blind Simulator does not do
Knowing the edges of a tool saves more time than another list of its features. These are the cases where it will not do what you might expect.
- The simulation is an approximation using simple linear matrices, not a clinically accurate model. It transforms a single colour and has no severity setting, so it cannot reflect the many degrees and rare forms of colour vision deficiency.
- Only a single colour is transformed at a time. There is no image or palette upload, no before-and-after view and no contrast or accessibility check - to test a whole design you would have to convert colours one at a time.
- Only the three main forms are offered. There is no achromatopsia or monochromacy, no anomalous trichromacy variants, and no option to input colours in another format such as rgb or hsl.
Tested and documented by itoolnet, the team that builds and maintains this site.