The Contrast Percentage Calculator is a tool designed to measure the difference in brightness or luminance between two areas, commonly referred to as the brighter and darker areas. This calculation is essential in fields such as design, photography, user interface development, and accessibility testing, where understanding and optimizing contrast can improve visibility, readability, and overall user experience. By determining the contrast percentage, users can ensure compliance with visual standards and enhance the quality of visual content.
Formula of Contrast Percentage Calculator
The contrast percentage is calculated using the formula:
Detailed Formula Components
- L1 (Luminance of the Brighter Area):
- The luminance or brightness of the lighter area, expressed in units such as candelas per square meter (cd/m²).
- L2 (Luminance of the Darker Area):
- The luminance or brightness of the darker area, expressed in the same units as L1.
Notes:
- L1 must always be greater than or equal to L2 for the formula to be valid.
- The result is expressed as a percentage, indicating the degree of contrast.
Precalculated Contrast Percentages
The following table provides some common luminance values and their corresponding contrast percentages for quick reference. These values can assist users without the need to calculate manually every time.
| Luminance of Brighter Area (L1) | Luminance of Darker Area (L2) | Contrast Percentage (%) |
|---|---|---|
| 100 cd/m² | 50 cd/m² | 50% |
| 100 cd/m² | 25 cd/m² | 75% |
| 100 cd/m² | 10 cd/m² | 90% |
| 200 cd/m² | 50 cd/m² | 75% |
| 200 cd/m² | 20 cd/m² | 90% |
| 300 cd/m² | 100 cd/m² | 66.67% |
Example of Contrast Percentage Calculator
Let’s calculate the contrast percentage for a specific case.
Scenario:
A webpage has text with a luminance of 150 cd/m² on a background with a luminance of 50 cd/m².
Using the formula: Contrast Percentage = [(L1 - L2) / L1] × 100
Substituting the values: Contrast Percentage = [(150 - 50) / 150] × 100 = (100 / 150) × 100 = 66.67%
Thus, the contrast percentage in this example is 66.67%.
Most Common FAQs
Contrast percentage ensures that text and visual elements are distinguishable from their background, improving readability and accessibility. It is crucial for users with visual impairments or color blindness.
Contrast percentage expresses the difference in brightness as a percentage, whereas contrast ratio compares luminance values in a ratio format (e.g., 4:1). Both methods serve accessibility evaluations but are apply differently.
Yes, many online tools and software, including accessibility plugins and standalone apps, provide automated calculations for contrast percentage based on input luminance values.