The sunscreen reapply timer counts down to when you need to reapply based on your SPF and activity level. Higher SPF does not extend reapplication time — all sunscreens should be reapplied every 2 hours, or every 80 minutes when swimming or sweating.
Set Up Your Timer
Defaults to current time
UV Safety Tips
- • Peak UV hours: 10 AM – 4 PM (highest between 12–2 PM)
- • Seek shade during peak hours when possible
- • Apply 15-30 min before going outside for full activation
- • Use 1 oz (a shot glass) to cover your whole body
- • Don't forget: lips, ears, back of neck, tops of feet
- • Cloudy days: up to 80% of UV rays penetrate clouds
- • Water & sand reflect UV — apply under beach umbrellas too
How to Use the Sunscreen Reapply Timer
The sunscreen reapply timer removes the guesswork from UV protection by counting down to when your sunscreen has degraded and needs a fresh coat. Most sunburns happen not because people skip sunscreen, but because they forget to reapply it.
The 2-Hour Rule (and Why SPF Doesn't Change It)
SPF (Sun Protection Factor) tells you the fraction of UV-B rays blocked: SPF 30 blocks 97%, SPF 50 blocks 98%. What SPF doesn't indicate is duration. All sunscreens — from SPF 15 to SPF 100 — break down at roughly the same rate from UV exposure, sweat, and activity. Dermatologists universally recommend reapplying every 2 hours, with the exception of swimming and heavy sweating which requires every 80 minutes.
Water Resistance vs Waterproof
"Water resistant" sunscreens are rated to maintain their SPF for either 40 or 80 minutes in water (the label specifies which). After that period, effectiveness drops significantly and reapplication is required. No sunscreen is truly "waterproof" — the FDA banned that claim in 2011. If your sunscreen says "80-minute water resistance," it means after 80 minutes of swimming, SPF effectiveness is no longer guaranteed.
How Much Sunscreen to Apply
Most people apply only 25-50% of the recommended amount, which can cut the effective SPF dramatically. The standard recommendation is 1 ounce (about a shot glass or a generous handful) for full-body coverage. For the face alone, use about a nickel-sized amount. Thin application of SPF 50 might only provide SPF 15-20 protection in practice. Apply generously before going outside, allow 15-30 minutes to fully absorb, then follow the reapplication timer.
FAQ
How often should you reapply sunscreen?
Sunscreen should be reapplied every 2 hours when outdoors, regardless of SPF level. If you are swimming or sweating heavily, reapply every 80 minutes — even if the product is labeled 'water resistant.' Higher SPF does not mean you can wait longer between applications.
Does higher SPF mean I can wait longer to reapply?
No. SPF measures the percentage of UV-B rays filtered (SPF 30 = 97%, SPF 50 = 98%), not how long protection lasts. All sunscreens break down at approximately the same rate from sweat, swimming, and UV exposure. Reapply every 2 hours regardless of whether you used SPF 15 or SPF 100.
Should I reapply sunscreen if I'm in the shade?
Yes, shade provides only partial protection. Tree shade blocks about 50% of UV rays, and reflected UV from sand, water, and buildings still reaches your skin. Apply sunscreen before going out, and reapply on schedule even if you spend time in the shade.
When are UV rays strongest?
UV radiation is strongest between 10 AM and 4 PM, with peak intensity around solar noon (12-2 PM depending on your location). UV is also stronger at higher altitudes, near water or sand (which reflect rays), and during summer months. The UV index above 6 warrants extra caution.
Is this sunscreen timer tool free?
Yes, completely free. No signup or account needed. The timer runs entirely in your browser — no data is sent to any server.