Watts per square meter (erythemal) to UV index
Type a value in W/m² to get it in UVI instantly.
320UVI
That's 16× as strong as the high Andes — nothing on our list beats it. That is extreme: unprotected skin burns in minutes.
Convert the other way: UVI to W/m²
What it means
How strong is that sun?
Information only. Burn times are for unprotected skin in full sun and vary a lot between people; sunscreen, shade and reflection from snow or water change them.
The math
How to convert W/m² to UVI
To convert watts per square meter (erythemal) to UV index, multiply by 40.
Example: 8 W/m² × 40 = 320 UVI.
In the other direction, 1 UVI = 0.025 W/m².
Burn times below are for Type II: fair, usually burns. Change it above and they update.
Every unit
Your UV index in every unit
Tables
W/m² to UVI conversion table
| W/m² | UVI |
|---|---|
| 1 W/m² | 40 UVI |
| 2 W/m² | 80 UVI |
| 3 W/m² | 120 UVI |
| 4 W/m² | 160 UVI |
| 5 W/m² | 200 UVI |
| 6 W/m² | 240 UVI |
| 7 W/m² | 280 UVI |
| 8 W/m² | 320 UVI |
| 9 W/m² | 360 UVI |
| 10 W/m² | 400 UVI |
| 11 W/m² | 440 UVI |
| 12 W/m² | 480 UVI |
| 14 W/m² | 560 UVI |
UVI to W/m² conversion table
| UVI | W/m² |
|---|---|
| 1 UVI | 0.025 W/m² |
| 2 UVI | 0.05 W/m² |
| 3 UVI | 0.075 W/m² |
| 4 UVI | 0.1 W/m² |
| 5 UVI | 0.125 W/m² |
| 6 UVI | 0.15 W/m² |
| 7 UVI | 0.175 W/m² |
| 8 UVI | 0.2 W/m² |
| 9 UVI | 0.225 W/m² |
| 10 UVI | 0.25 W/m² |
| 11 UVI | 0.275 W/m² |
| 12 UVI | 0.3 W/m² |
| 14 UVI | 0.35 W/m² |
Quick answers
Quick answers
- How many UVI is 1 W/m²?
- 1 W/m² is 40 UVI.
- How many UVI is 10 W/m²?
- 10 W/m² is 400 UVI.
- How many UVI is 8 W/m²?
- 8 W/m² is 320 UVI.
The units
About these units
Watts per square meter (erythemal) (W/m²)
The same in SI watts.
UV index (UVI)
The WHO scale: 25 mW/m² of sunburn-weighted UV per point.
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