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Color Blindness Simulator Calculator

Estimate how many users are affected by a colour-dependent interface.

About Color Blindness Simulator Calculator

Colour vision deficiency is X-linked, so prevalence among men is roughly twenty times that among women. On a service with a hundred thousand users, several thousand cannot reliably distinguish red from green. WCAG requires that colour is never the sole means of conveying information, and adding an icon or label costs almost nothing compared with the share of users it serves.

Formula

Color Blindness Simulator

Affected users = male users × male prevalence + female users × female prevalence

red-green deficiency
The most common form, affecting about 8 per cent of men
X-linked inheritance
Why prevalence is far higher in men than women

Worked example

With the default values below, Color Blindness Simulator Calculator returns Users Affected of 4,176. Change any input above and every figure here is recalculated in your browser.

Inputs used

Monthly usersminimum 0
120,000
Share of users who are maleaccepts 0–100 %
55 %
Deficiency modelledone of Deuteranomaly, red-green, Protanopia, red-green, Tritanopia, blue-yellow, All types combined
Deuteranomaly, red-green
Indicators conveyed by colour aloneminimum 0
4

Results

Users Affected
4,176
Share of Users Affected
3.480%
Prevalence Among Male Users
6.00%
Prevalence Among Female Users
0.400%
Remediation Note
Several colour-only indicators — add icons, text labels or patterns alongside colour

Step by step

  1. 1Values used
  2. 2Color Blindness Simulator
  3. 3Users Affected= 4,176
  4. 4Share of Users Affected= 3.480
  5. 5Prevalence Among Male Users= 6.00
  6. 6Prevalence Among Female Users= 0.400
  7. 7Remediation Note= Several colour-only indicators — add icons, text labels or patterns alongside colour

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Color Blindness Simulator calculated?

Affected users = male users × male prevalence + female users × female prevalence Colour vision deficiency is X-linked, so prevalence among men is roughly twenty times that among women. On a service with a hundred thousand users, several thousand cannot reliably distinguish red from green.

Why does Color Blindness Simulator matter?

WCAG requires that colour is never the sole means of conveying information, and adding an icon or label costs almost nothing compared with the share of users it serves.

What values do I need to enter?

This calculator takes 4 inputs: Monthly users, Share of users who are male, Deficiency modelled, Indicators conveyed by colour alone. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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