Sunbathing Calculator

Estimate safe sun-exposure time with sunscreen.

Sunscreen SPF

UV index

Burn time at UV 1

Safe exposure 857.14

Formula: safe = burn time / UV index * SPF

Step-by-step with your numbers:

1. Values used:

2. Sunscreen SPF = 30

3. UV index = 7

4. Burn time at UV 1 = 200

6. Safe exposure = 857.14

Did we solve your problem today?

Sunscreen multiplies the time before you burn, while a higher UV index shortens it.

The math behind it

safe time = (your burn time at UV 1 / UV index) x SPF. Reapply regularly - SPF wears off.

SPF 30 at UV 7 with a 200-minute base burn time gives about 857 minutes (but reapply!).

Is this exact?

No - it's a guide; sweat, water and uneven application reduce real protection.