Sunscreen Calculator

Your details

The Fitzpatrick scale classifies how your skin reacts to UV exposure. Type I burns immediately; Type VI almost never burns. This determines your unprotected burn time.
The daily peak UV index forecast for your location. Check a weather app or the EPA UV Index app. Typical values: 1-2 low, 3-5 moderate, 6-7 high, 8-10 very high, 11+ extreme.
SPF (Sun Protection Factor) measures how much longer your skin can be in the sun before burning. SPF 30 blocks about 97% of UVB; SPF 50 blocks about 98%. Dermatologists generally recommend SPF 30 or higher.
How many total hours you plan to spend in direct or partial sunlight.
hrs
Number of consecutive days you will be applying sunscreen. Used to estimate bottles needed.
days
The capacity of the sunscreen bottle you are packing. Needed to estimate how many you need.
Includes face, ears, scalp (if not covered by hair) and neck. ~450 cm2.
Upper arms, forearms and the backs of hands. ~2,700 cm2 combined.
Front of chest and décolletage area. ~1,800 cm2.
Front abdominal area. ~1,500 cm2.
Upper back and shoulders. ~1,700 cm2.
Lower back. ~1,300 cm2.
Both thighs, front and back. ~3,200 cm2 combined.
Both calves, shins and tops of feet. ~3,000 cm2 combined.
Protection durationFully protected for 2 hrs
2hrs

How long your SPF protection lasts before reapplication is needed

Sunscreen per application6.3mL
Reapplications needed today1
Total sunscreen per day12.6mL
Bottles needed for trip0.6
Total area covered3,150cm2
2 hrs
Very low - reapply often<0.5Low - reapply hourly0.5-1Moderate protection1-1.5Full 2-hr protection1.5+

Your SPF 30 protects for up to 2.0 hours at UV index 6.

  • Apply 6.3 mL to the selected areas, which is the 2 mg/cm2 amount used in lab testing to certify that SPF rating.
  • With 4 hours outdoors, reapply 1 more time during the day.
  • UV index 6 is high. A broad-spectrum SPF 30 is appropriate; cover up during peak hours.
  • Pack at least 1 bottle for your 7-day trip.

Next stepApply sunscreen 15-30 minutes before going outside so it can bond to your skin before UV exposure begins.

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