How Often to Reapply Sunscreen (and When 2 Hours Is Too Long)

Updated 21 September 2026

Why every 2 hours

Sunscreen does not simply expire on your skin after 2 hours. It rubs off on clothes and towels, washes off with sweat and water, and gets missed in spots you did not cover well the first time. Reapplying every 2 hours tops up the layer and catches the gaps.

Reapply sooner when

• you have been in the water, even with water resistant sunscreen
• you towelled off, since rubbing removes most of the layer
• you are sweating a lot from exercise or heat
• the UV index is 8 or higher and you are in direct sun

How much is enough

For the SPF on the label to be close to true you need about 2 mg per square centimetre. For an adult that is roughly a shot glass, about 30 ml, for the whole body, and half a teaspoon for the face and neck. Most people use a quarter to a half of that, which is why real-world protection is lower than the number on the bottle.

Mistakes that lead to burns

• Applying once in the morning and considering the day done.
• Missing ears, the back of the neck, feet and the parting in your hair.
• Relying on a moisturiser with SPF for a long day outdoors.
• Using last summer's bottle that sat in a hot car. Check the expiry date.

Never forget to reapply

A phone alarm works, but it does not know when you went in the water. UV Safe Tan starts a reapply countdown when you tap that you applied sunscreen, reminds you with a notification when it is due, and shows the countdown on your Lock Screen as a Live Activity. Tap Reapplied and the clock resets.

UV Safe Tan is coming soon

Live UV index for where you are, a burn timer set by your skin type and SPF, reapply reminders, a tan timer that stops before you burn, and Home Screen widgets. For iPhone and iPad.

Coming soon to theApp Store

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