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Calcimator

SPF Effective Protection Calculator

Calculate your actual UV protection based on SPF rating, application thickness, and time since application.

Inputs

%
min

Results

Current Effective SPF

1.7

Current UVB Blocked41%
Label UVB Blocked (full application)96.7%
Reapply In20 min
Label SPF30
How to Use This Calculator
  1. Enter the SPF rating printed on your sunscreen label.
  2. Set the application amount as a percentage of the recommended 2 mg per cm2 (most people apply about 50%).
  3. Enter the number of minutes since you last applied sunscreen.
  4. Toggle the Swimming/Sweating option if you have been in water or exercising.
  5. Input the current UV Index from your weather app.
  6. Review Current Effective SPF and Reapply In time to know exactly when to reapply.
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