Colour Blindness Simulator
Check whether your charts, maps and designs still work for people who see colour differently.
- Your data never leaves your device
- 100% free
- No sign-up
- Works offline after first load
How to simulate colour blindness
- Drop, paste or choose an image — or use the sample chart.
- Pick a vision type and the view: split, side by side or all types.
- Download the simulated image or a comparison sheet.
About Color Blindness Sim
See any image as people with colour blindness do.
Everything works in your browser, so it is instant and private. Your recent colours and settings are remembered on this device, and the address bar keeps your colour so you can share or bookmark it.
Good for
- Checking charts, maps and dashboards
- Accessible UI and graphic design
- Teaching and awareness
Tip: Charts relying only on red versus green fail for most colour-blind people — add labels or patterns.
Frequently asked questions
How accurate is the simulation?
It uses the Machado, Oliveira and Fernandes (2009) model in linear RGB — the method used by Chrome DevTools and most accessibility tools — with adjustable severity for the milder anomalies.
How common is colour blindness?
About 1 in 12 men and 1 in 200 women. Deuteranomaly (weak green) is the most common; tritan types and full colour blindness are rare.
Is my image uploaded?
No. The image is processed on a canvas in your browser — nothing is sent to a server.
Can I check my colour palette?
Yes — list colours in the side panel to see each one per vision type, with a warning for pairs that become hard to tell apart.
Which types can it simulate?
Protanopia, deuteranopia and tritanopia (missing red, green or blue cones), their milder forms, and achromatopsia (no colour vision).