Safe sun time calculator

By Trung Hieu Lam, developer of UV Tracker · Published 1 September 2026

Pick your skin type and today's UV index. This uses the same formula as the safe sun time tables — no data leaves your browser.

The full table

With JavaScript off, or for a quick scan of every combination:

UV index	Type I	Type II	Type III	Type IV	Type V	Type VI
1	133	167	233	300	400	667
2	67	83	117	150	200	333
3	44	56	78	100	133	222
4	33	42	58	75	100	167
5	27	33	47	60	80	133
6	22	28	39	50	67	111
7	19	24	33	43	57	95
8	17	21	29	38	50	83
9	15	19	26	33	44	74
10	13	17	23	30	40	67
11	12	15	21	27	36	61

How this is calculated

1 UV index unit equals 1.5 J/m² of erythemal dose per minute, so minutes of safe sun time = MED ÷ (UV index × 1.5), where MED is your skin type's Minimal Erythemal Dose (Type I 200 J/m² through Type VI 1000 J/m²). See the full tables article for the sources.

For the sunscreen figure, the theoretical maximum is safe sun time × SPF. In practice, most people apply well under half the thickness sunscreen is tested at, so real-world protection runs far below the label number — treat the protected figure here as an optimistic ceiling, not a target, and reapply every two hours regardless.

UV Tracker measures the UV where you stand — sky scan for local conditions, one photo for your skin type, and your safe sun time on one card. Free forever.

References

World Health Organization, Global Solar UV Index: A Practical Guide. Accessed 2026-09-01.
US Environmental Protection Agency, UV Index Scale. Accessed 2026-09-01.
Fitzpatrick TB. "The validity and practicality of sun-reactive skin types I through VI." Archives of Dermatology, 1988.
"The effect of an ultraviolet photography educational exercise on sunscreen application: A pilot study." Journal of the American Academy of Dermatology, research letter.

UV forecast data in the app: Open-Meteo.

This article is general information, not medical advice. Sun-exposure estimates are approximations. If you have concerns about your skin, or a history of skin cancer in your family, see a doctor or dermatologist.

UV index	Type I	Type II	Type III	Type IV	Type V	Type VI
1	133	167	233	300	400	667
2	67	83	117	150	200	333
3	44	56	78	100	133	222
4	33	42	58	75	100	167
5	27	33	47	60	80	133
6	22	28	39	50	67	111
7	19	24	33	43	57	95
8	17	21	29	38	50	83
9	15	19	26	33	44	74
10	13	17	23	30	40	67
11	12	15	21	27	36	61

UV index	Type I	Type II	Type III	Type IV	Type V	Type VI
1	133	167	233	300	400	667
2	67	83	117	150	200	333
3	44	56	78	100	133	222
4	33	42	58	75	100	167
5	27	33	47	60	80	133
6	22	28	39	50	67	111
7	19	24	33	43	57	95
8	17	21	29	38	50	83
9	15	19	26	33	44	74
10	13	17	23	30	40	67
11	12	15	21	27	36	61

UV index	Type I	Type II	Type III	Type IV	Type V	Type VI
1	133	167	233	300	400	667
2	67	83	117	150	200	333
3	44	56	78	100	133	222
4	33	42	58	75	100	167
5	27	33	47	60	80	133
6	22	28	39	50	67	111
7	19	24	33	43	57	95
8	17	21	29	38	50	83
9	15	19	26	33	44	74
10	13	17	23	30	40	67
11	12	15	21	27	36	61