Plan sunscreen reapplication for a full outdoor day.
The outdoor day is divided by the reapply interval to count touch-ups, plus the initial application. Sunscreen fades with sweat and exposure, and missed reapplication is the biggest cause of burns.
SPF Reapplication
Reapplications = ceil(hours / reapply window) - 1
Reapplications = ceil(hours / reapply window) - 1 The outdoor day is divided by the reapply interval to count touch-ups, plus the initial application.
Sunscreen fades with sweat and exposure, and missed reapplication is the biggest cause of burns.
This calculator takes 4 inputs: SPF, Outdoor hours, Reapply every, Per application. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.