# Contrast Ratio Calculator (WCAG)

> Contrast ratio calculator: test text and background colors against WCAG AA and AAA thresholds for accessible color contrast. Free, runs in your browser.

- **Canonical URL:** https://boringtoolskit.com/contrast-ratio-calculator/
- **Category:** Everyday Calculators
- **Evidence level:** authored-methodology
- **Reviewed:** July 26, 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

Contrast = (L1 + 0.05) / (L2 + 0.05) using relative luminance L = 0.2126R + 0.7152G + 0.0722B (sRGB, gamma-corrected).

## Worked example

#14243a on #f6f5ef gives a 14.31:1 ratio, which passes WCAG AAA for normal text (needs 4.5:1).

## Common questions

### What is a contrast ratio calculator and how does it work?

A contrast ratio calculator is a browser-based tool that measures the luminance difference between two colors to ensure they meet WCAG accessibility standards, requiring no signup or data storage.

### How do I use the contrast ratio calculator to check WCAG compliance?

Simply input your foreground and background hex or RGB values into the contrast ratio calculator, and it will instantly display the ratio and whether it passes AA or AAA standards for normal and large text.

### Do I need to create an account or share my data to use this contrast ratio calculator?

No, this is a completely no-signup, browser-based tool that processes all color calculations locally on your device, ensuring your data never leaves your computer.

## Sources

- [Calculation methodology](/methodology/)
- [Quality evidence and verification standard](/quality-evidence/)

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