Sun Exposure Time to Burn Calculator

Calculate personalized time to burn based on UV index skin type sunscreen quality altitude cloud cover shade and ground reflection Get precise minutes with pro features instant results safety notes and practical reapply guidance for outdoor work sports beach days and daily planning track UV risk across seasons learn limits protect children sensitive skin

Inputs

Determines minimal erythema dose (MED).
From weather apps or a UV meter.
UV rises ~12% per 1000 m.
Enter 1 for no sunscreen.
Real‑world protection is lower than the SPF label.

Results

Enter the UV index and conditions to estimate how long exposed skin may take to start reddening. Choose your Fitzpatrick skin type and optionally add sunscreen, altitude, and surface effects.

Safety notes

  • Reapply sunscreen every 2 hours, or sooner if swimming/sweating.
  • Seek shade during midday hours when UVI typically peaks.
  • Cover up with UPF clothing, hats, and sunglasses.
  • Babies and children need extra protection; consult local guidance.

FAQs

How is the time to burn calculated?

The calculator divides your skin’s minimal erythema dose (MED) by effective erythemal irradiance. Irradiance is estimated from the UV index and adjusted for altitude, cloud cover, shade, and surface reflection.

What are Fitzpatrick skin types?

A six‑type scale that describes how skin responds to sunlight. Type I usually burns quickly, while Type VI rarely burns. Your type changes the MED used in the estimate.

Does SPF linearly increase safe time?

In perfect labs SPF multiplies time, but real‑world protection is lower due to application thickness, missed spots, and wear. We apply a quality factor to reflect this.

Do clouds always reduce UV exposure?

Often, but not always. Thin or broken clouds can scatter light and sometimes increase ground‑level UV. Choose the option that best matches current conditions.

Why does altitude change the result?

Air is thinner at higher elevations, letting more UV reach the surface. A rule of thumb is about 10–12% more UV per 1000 m of elevation gain.

What about reflection from water, sand, or snow?

Reflective surfaces bounce UV back onto skin, increasing effective exposure. Snow is most intense, while water and sand give smaller but meaningful increases.

Is this medical advice?

No. It’s an educational estimate. Individual sensitivity varies with medications, recent exposure, and skin care. When in doubt, protect more and consult a professional.

How often should I reapply sunscreen?

Common guidance is every two hours and after swimming or heavy sweating, regardless of the SPF value shown on the label.

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.