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Calcimator

Sun Protection Calculator

Calculate safe sun exposure time, reapplication schedule, and sunscreen needs based on UV index, skin type, and SPF.

Inputs

ft
min

Results

Burn Time (No SPF)

17min

Protected Burn Time

300min

Effective UV Index6
Reapply Every120min
Reapplications Needed0
Total Sunscreen0cup
UV Risk Level3
UVB Blocked97%
How to Use This Calculator
  1. Enter the current UV Index for your location (check a weather app or UV forecast).
  2. Select your Skin Type (Fitzpatrick I-VI) and the Sunscreen SPF being used.
  3. Enter Altitude and toggle Near Water/Snow to account for UV reflection.
  4. Enter Time Outdoors (min) to assess cumulative exposure.
  5. Review Protected Burn Time, Reapply Interval, and Effective UV Index to plan sun safety.

How the result changes with UV Index

UV IndexBurn Time (No SPF)Protected Burn Time
1.567min1,200min
5.2519min343min
9.7510min185min
147min129min

What each input means

UV Index
Current UV index from weather forecast.
Skin Type
Fitzpatrick type 1–6.
Sunscreen SPF
Sun Protection Factor.
Altitude
UV increases ~4% per 1,000 ft.
Near Water/Snow
0=no, 1=yes. Adds ~50% UV.
Time Outdoors
Planned outdoor time.

What each result means

UV Risk Level
1=low to 5=extreme.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    UV Index = 6, Skin Type = 2, Sunscreen SPF = 30, Altitude = 0 = 6 input(s) provided
  2. Calculate Burn Time
    17 = 17
  3. Calculate Protected Burn Time
    300 = 300
  4. Calculate Effective UV Index
    6 = 6
  5. Calculate Reapply Every
    Reapply Every = min(120, protectedBurnMin * 0.75)
    120 = 120

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