Screen Calibration — Vision Tests

1. Match the box to a credit card

The box starts at an automatic size estimate for a typical screen. Hold any standard plastic card (credit, debit, ID — they're all 85.6 mm wide) flat against your screen and fine-tune the slider until the box is exactly the same size. Make sure your browser zoom is at 100% (Ctrl+0).

Credit card

Verify (optional): the bar below should measure exactly 100 mm with a real ruler.

2. Choose your viewing distance

How far will you sit from the screen during the acuity test? Farther is more accurate — use 2 m or more if your room allows it.

Or custom: m

Medical disclaimer: These are screening tools only and are still in development, not a medical diagnosis. Consult an eye-care professional for any concerns about your vision.