Clinical Sunscreen Dosage (2 mg/cm²) & UV Drop-Off Calculator
Calculate the exact milliliter volume required for true ISO 24444 broad-spectrum photoprotection, how long your bottle should last, and the exponential SPF drop-off when under-applying.
How Generously Do You Apply?100% of Clinical 2 mg/cm² Dose (1.6 mL)
25% (Light skim)50% (Average consumer application)100% (Clinical standard)
Actual Biological UV Protection
SPF 50(Stated: SPF 50)
Full 2 mg/cm² coverage achieved. You are receiving the full rated photoprotection.
Bottle Shelf Lifespan
31days of daily single-use
A 50 mL bottle used correctly once daily should finish in approximately 31 days (approx 1.0 months). If your bottle lasts 6+ months, you are under-applying!
How to Measure Without a Kitchen Scale:
3 full finger lengths (or 1/3 level teaspoon)
The two-finger rule applies to standard lotion-type sunscreens. For liquid, water-thin sunscreens (like Japanese milk sunscreens), measure approximately 1/3 of a level measuring teaspoon to achieve 1.25 mL.