Sunscreen Amount Calculator
Calculate how much sunscreen you need per application based on body area and SPF.
Includes reapplication schedule.
Sunscreen Needed
Dermatologists recommend 2 mg of sunscreen per square centimeter of skin for the SPF rating to be accurate.
Standard amounts per body area:
- Face and neck: ~1 teaspoon (5 mL)
- Each arm: ~1 teaspoon (5 mL)
- Each leg: ~2 teaspoons (10 mL)
- Chest: ~1 teaspoon (5 mL)
- Back: ~2 teaspoons (10 mL)
- Full body (adult): ~7 teaspoons (35 mL) or about 1 shot glass
Reapplication rules:
- Reapply every 2 hours regardless of SPF
- Reapply immediately after swimming or heavy sweating
- SPF 30 blocks ~97% of UVB; SPF 50 blocks ~98%
- No sunscreen blocks 100% of UV rays
How long a bottle lasts: A 200 mL bottle used for full-body application lasts about 5-6 applications.