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Deuteranopia Simulator

DesignDesign Utilities

3- or 6-digit hex codes, with or without #. Up to 50.

First colour as seen with deuteranopia —
Colours checked
—
Average RGB shift
—
Pairs that merge
—

Enter hex colours and the simulator shows each one as a person with deuteranopia (no working green cones) would see it. It uses the Machado 2009 model in linear RGB: pure red #FF0000 becomes a dark mustard #A39000, while greys and white stay the same. Colour pairs that collapse into similar tones are listed as warnings.

About this tool

Roughly 1 in 100 men has deuteranopia or a strong form of deuteranomaly, so a palette that relies on red versus green can lose its meaning for part of any audience. Designers checking chart series, status badges or map legends need to know which colours survive. Paste a palette here and each hex code is converted to its simulated deuteranopia appearance, with the RGB distance it moved and a count of colour pairs that were distinct but now sit close together. The table lets you compare the original and simulated codes side by side, and you can paste the new codes into any design tool to preview them. The model approximates full deuteranopia on a standard sRGB display; it cannot show exactly what any one person perceives, and milder deuteranomaly looks less extreme than this.

How to use it

  1. Paste your palette

    Enter hex codes such as #2CA02C or 3a7, separated by spaces, commas or line breaks. Up to 50 at once.

  2. Read the simulated codes

    The headline shows the first colour as seen with deuteranopia; the table lists every colour with its simulated hex and how far it shifted.

  3. Check merged pairs

    Warnings name colour pairs that differ clearly now but end up close after simulation, the ones to fix with lightness or a pattern.

Examples

Pure red

Hex colours
#FF0000

Result First colour as seen with deuteranopia: #A39000
Colours checked: 1
Average RGB shift: 170.9
Pairs that merge: 0

  1. Each sRGB channel is linearised: c/255, then ((c + 0.055)/1.055)^2.4 above 0.04045.
  2. Linear RGB is multiplied by the Machado (2009) deuteranopia matrix, row one: 0.367322 R + 0.860646 G − 0.227968 B.
  3. The result is clipped to 0–1 and gamma-encoded back to sRGB hex.
  4. A pair is flagged when it differs by 60 or more in RGB distance but by less than 50 after simulation.

Bright red loses its hue and turns a dark olive-mustard, which is why red alone is a weak signal for someone with deuteranopia.

A rose and an olive in one chart

Hex colours
#CC6666 #999933

Result First colour as seen with deuteranopia: #968D64
Colours checked: 2
Average RGB shift: 40.9
Pairs that merge: 1

  1. Each sRGB channel is linearised: c/255, then ((c + 0.055)/1.055)^2.4 above 0.04045.
  2. Linear RGB is multiplied by the Machado (2009) deuteranopia matrix, row one: 0.367322 R + 0.860646 G − 0.227968 B.
  3. The result is clipped to 0–1 and gamma-encoded back to sRGB hex.
  4. A pair is flagged when it differs by 60 or more in RGB distance but by less than 50 after simulation.

Clearly different for most viewers, these two become two similar khaki tones, so the pair is flagged.

How it is calculated

RGB_sim = M_deut × RGB_linear, then gamma-encode to sRGB

RGB_linear
the input colour with the sRGB gamma removed, each channel 0 to 1
M_deut
the Machado, Oliveira and Fernandes (2009) 3×3 matrix for deuteranopia at severity 1.0
RGB shift
straight-line distance between the original and simulated colours on the 0–255 scale

Each hex code is split into red, green and blue, linearised with the sRGB transfer curve, and multiplied by the Machado deuteranopia matrix, which models the medium-wavelength cone response being absent. Values outside 0–1 are clipped before re-encoding. Because each matrix row sums to 1, greys keep their exact value. A pair is reported as merging when it starts at least 60 apart in RGB distance and ends less than 50 apart.

When not to use it

  • To test protanopia or tritanopia, which need different matrices and shift colours in other directions.
  • As a diagnosis or vision test; it shows a model of a palette, not how your own eyes work.
  • For wide-gamut or print colours, since the model assumes sRGB screen values.

Common mistakes

  • Checking only hue and forgetting that two colours with the same lightness are the hardest pair to separate.
  • Assuming a palette passes because red and green look different here, when chart labels or patterns are still missing.
  • Entering colour names like teal instead of hex codes; names are skipped.

Frequently asked questions

What is deuteranopia?

Deuteranopia is a form of red-green colour vision deficiency in which the medium-wavelength (green) cones are missing. Reds, oranges, yellows and greens fall onto a narrow range of yellowish and brownish tones, while blues and greys look much as they do with typical vision.

Why does pure red turn into a dark yellow?

Without green cones, the eye compares long-wavelength light against short-wavelength light only. Pure red stimulates the long-wavelength cones, so it reads as a warm, fairly dark yellow-brown. In this model #FF0000 becomes #A39000.

How is this different from deuteranomaly?

Deuteranomaly is the milder and far more common variant: the green cones exist but their sensitivity is shifted toward red. This simulator uses severity 1.0, the full loss, so it shows the worst case. A palette that works here also works for milder forms.

Which colours are safest for people with deuteranopia?

Blue against orange, and dark against light, survive well. Problems come from red, green, brown and olive tones of similar lightness. Adding text labels, patterns or line styles removes the reliance on colour altogether.

What does the RGB shift number mean?

It is the straight-line distance between the original and simulated colours in 0–255 RGB space. Zero means the colour looks the same; pure green moves about 249, showing it changes more than any other primary.

Are my colours sent anywhere?

No. The matrix maths runs in your browser, and the hex codes you paste are not stored on any server.

Cite this tool

Using this tool in an assignment, article or report? Copy a citation, or a link for your website.

APA

Tools Directory Editorial Team. (2026, October 23). Deuteranopia Simulator. Tools Directory. Retrieved October 26, 2026, from https://tools.milunir.com/design/design-utilities/deuteranopia-simulator/

MLA

Tools Directory Editorial Team. “Deuteranopia Simulator.” Tools Directory, 23 Oct. 2026, https://tools.milunir.com/design/design-utilities/deuteranopia-simulator/. Accessed 26 Oct. 2026.

Chicago

Tools Directory Editorial Team. “Deuteranopia Simulator.” Tools Directory. Last modified October 23, 2026. Accessed October 26, 2026. https://tools.milunir.com/design/design-utilities/deuteranopia-simulator/.

Link<a href="https://tools.milunir.com/design/design-utilities/deuteranopia-simulator/">Deuteranopia Simulator – Tools Directory</a>