Watts per square metre to BTU per hour square foot
Convert watts per square metre to BTU per hour square foot instantly.
Watts per square metre to BTU per hour square foot (W/m² to BTU/(h·ft²)) Converter
1 watt per square metre = 0.317 BTU per hour square foot
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- 1 W/m² = 0.317 BTU/(h·ft²)
- 5 W/m² = 1.585 BTU/(h·ft²)
- 10 W/m² = 3.17 BTU/(h·ft²)
- 25 W/m² = 7.925 BTU/(h·ft²)
- Watts per square metreW/m²
- BTU per hour square footBTU/(h·ft²)
- Watts per square metreW/m²
- BTU per hour square footBTU/(h·ft²)
How it’s calculated
BTU/(h·ft²) = W/m² × 0.3169983306
- Multiply the value in watts per square metre by 0.3169983306.
- To go back, divide by 0.3169983306 (or multiply by 3.154590745).
- 1 W/m² = 0.3169983306 BTU/(h·ft²) · 1 BTU/(h·ft²) = 3.154590745 W/m²
Quick examples
1 watt per square metre = 0.317 BTU per hour square foot · 1 BTU/(h·ft²) = 3.1546 W/m²
- 1 watt per square metre = 0.317 BTU per hour square foot
- 5 watts per square metre = 1.585 BTU per hour square foot
- 10 watts per square metre = 3.17 BTU per hour square foot
- 25 watts per square metre = 7.925 BTU per hour square foot
- 100 watts per square metre = 31.7 BTU per hour square foot
Watts per square metre to BTU per hour square foot conversion table
| Watts per square metre (W/m²) | BTU per hour square foot (BTU/(h·ft²)) |
|---|---|
| 0.1 W/m² | 0.0317 BTU/(h·ft²) |
| 0.5 W/m² | 0.1585 BTU/(h·ft²) |
| 1 W/m² | 0.317 BTU/(h·ft²) |
| 2 W/m² | 0.634 BTU/(h·ft²) |
| 3 W/m² | 0.95099 BTU/(h·ft²) |
| 4 W/m² | 1.268 BTU/(h·ft²) |
| 5 W/m² | 1.585 BTU/(h·ft²) |
| 6 W/m² | 1.902 BTU/(h·ft²) |
| 7 W/m² | 2.219 BTU/(h·ft²) |
| 8 W/m² | 2.536 BTU/(h·ft²) |
| 9 W/m² | 2.853 BTU/(h·ft²) |
| 10 W/m² | 3.17 BTU/(h·ft²) |
| 15 W/m² | 4.755 BTU/(h·ft²) |
| 20 W/m² | 6.34 BTU/(h·ft²) |
| 25 W/m² | 7.925 BTU/(h·ft²) |
| 30 W/m² | 9.5099 BTU/(h·ft²) |
| 40 W/m² | 12.68 BTU/(h·ft²) |
| 50 W/m² | 15.85 BTU/(h·ft²) |
| 75 W/m² | 23.775 BTU/(h·ft²) |
| 100 W/m² | 31.7 BTU/(h·ft²) |
| 250 W/m² | 79.25 BTU/(h·ft²) |
| 500 W/m² | 158.5 BTU/(h·ft²) |
| 1,000 W/m² | 317 BTU/(h·ft²) |
About these units
Watt per square metre (W/m²)
SI (metric)
Base unit
The SI unit of heat flux (and irradiance). Solar irradiance at ground is about 1,000 W/m².
Source: BIPM SI Brochure (9th ed.)
BTU per hour square foot (BTU/(h·ft²))
US & imperial (identical)
1 BTU/(h·ft²) ≈ 3.1545907 W/m²
BTU per hour per square foot, about 3.1546 W/m².
Source: NIST SP 811 / Handbook 44
Frequently asked questions
How do I convert watts per square metre to BTU per hour square foot?
Use BTU/(h·ft²) = W/m² × 0.3169983306. Multiply the value in watts per square metre by 0.3169983306.
How many BTU per hour square foot are in 1 watt per square metre?
1 watt per square metre (W/m²) equals 0.317 BTU per hour square foot (BTU/(h·ft²)); more precisely 0.3169983306.
How many watts per square metre are in 1 BTU per hour square foot?
1 BTU per hour square foot (BTU/(h·ft²)) equals 3.1546 watts per square metre (W/m²); more precisely 3.154590745.
What is 10 W/m² in BTU/(h·ft²)?
10 watts per square metre = 3.17 BTU per hour square foot.
What is a watt per square metre?
The SI unit of heat flux (and irradiance). Solar irradiance at ground is about 1,000 W/m².
What is a BTU per hour square foot?
BTU per hour per square foot, about 3.1546 W/m².
Related conversions
Formula: BTU/(h·ft²) = W/m² × 0.3169983306. Factors last reviewed 2026-10-27.