Milliwatts per square meter (erythemal) to UV index
Type a value in mW/m² to get it in UVI instantly.
Nothing on our list is smaller: a northern winter day is 3.1× stronger. That is low: little protection needed.
Convert the other way: UVI to mW/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 mW/m² to UVI
To convert milliwatts per square meter (erythemal) to UV index, multiply by 0.04.
Example: 8 mW/m² × 0.04 = 0.32 UVI.
In the other direction, 1 UVI = 25 mW/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
mW/m² to UVI conversion table
| mW/m² | UVI |
|---|---|
| 1 mW/m² | 0.04 UVI |
| 2 mW/m² | 0.08 UVI |
| 3 mW/m² | 0.12 UVI |
| 4 mW/m² | 0.16 UVI |
| 5 mW/m² | 0.2 UVI |
| 6 mW/m² | 0.24 UVI |
| 7 mW/m² | 0.28 UVI |
| 8 mW/m² | 0.32 UVI |
| 9 mW/m² | 0.36 UVI |
| 10 mW/m² | 0.4 UVI |
| 11 mW/m² | 0.44 UVI |
| 12 mW/m² | 0.48 UVI |
| 14 mW/m² | 0.56 UVI |
UVI to mW/m² conversion table
| UVI | mW/m² |
|---|---|
| 1 UVI | 25 mW/m² |
| 2 UVI | 50 mW/m² |
| 3 UVI | 75 mW/m² |
| 4 UVI | 100 mW/m² |
| 5 UVI | 125 mW/m² |
| 6 UVI | 150 mW/m² |
| 7 UVI | 175 mW/m² |
| 8 UVI | 200 mW/m² |
| 9 UVI | 225 mW/m² |
| 10 UVI | 250 mW/m² |
| 11 UVI | 275 mW/m² |
| 12 UVI | 300 mW/m² |
| 14 UVI | 350 mW/m² |
Quick answers
Quick answers
- How many UVI is 1 mW/m²?
- 1 mW/m² is 0.04 UVI.
- How many UVI is 10 mW/m²?
- 10 mW/m² is 0.4 UVI.
- How many UVI is 8 mW/m²?
- 8 mW/m² is 0.32 UVI.
The units
About these units
Milliwatts per square meter (erythemal) (mW/m²)
Sunburn-weighted UV irradiance.
UV index (UVI)
The WHO scale: 25 mW/m² of sunburn-weighted UV per point.
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