BTU per hour square foot to Watts per square metre
1 BTU per hour square foot = 3.1546 watts per square metre · 1 W/m² = 0.317 BTU/(h·ft²)
1 BTU per hour square foot = 3.1546 watts per square metre
How it’s calculated
W/m² = BTU/(h·ft²) × 3.154590745
- Multiply the value in BTU per hour square foot by 3.154590745.
- To go back, divide by 3.154590745 (or multiply by 0.3169983306).
- 1 BTU/(h·ft²) = 3.154590745 W/m² · 1 W/m² = 0.3169983306 BTU/(h·ft²)
Show worked solutionFactor, unit cancellation and rounding, step by step
Find the conversion factor
By definition 1 BTU/(h·ft²) = 3.15459074506305 W/m². Source: NIST SP 811 / Handbook 44; BIPM SI Brochure (9th ed.).
Multiply by the factor written as a fraction
Put BTU/(h·ft²) in the denominator so it cancels, leaving W/m².
Calculate (unrounded)
Round the answer
Rounded to 5 significant figures.
Answer: 3.1546 W/m²
1 BTU/(h·ft²) in other units
Batch convert BTU/(h·ft²) → W/m²
- 1 BTU/(h·ft²) = 3.1546 W/m²
- 5 BTU/(h·ft²) = 15.773 W/m²
- 10 BTU/(h·ft²) = 31.546 W/m²
- 25 BTU/(h·ft²) = 78.865 W/m²
Quick examples
- 1 BTU per hour square foot = 3.1546 watts per square metre
- 5 BTU per hour square foot = 15.773 watts per square metre
- 10 BTU per hour square foot = 31.546 watts per square metre
- 25 BTU per hour square foot = 78.865 watts per square metre
- 100 BTU per hour square foot = 315.46 watts per square metre
About these units
BTU per hour square foot (BTU/(h·ft²))
US & imperial (identical)
IT BTU basis: ≈ 3.154 591 W/m².
1 BTU/(h·ft²) = 3.154590745 W/m²
Source: NIST SP 811 / Handbook 44
Watt per square metre (W/m²)
SI (metric)
SI unit of heat flux (and irradiance). Solar irradiance at ground ≈ 1 000 W/m².
Base unit
Source: BIPM SI Brochure (9th ed.)
BTU per hour square foot to watts per square metre conversion table
| BTU per hour square foot (BTU/(h·ft²)) | Watts per square metre (W/m²) |
|---|---|
| 0.1 BTU/(h·ft²) | 0.31546 W/m² |
| 0.5 BTU/(h·ft²) | 1.5773 W/m² |
| 1 BTU/(h·ft²) | 3.1546 W/m² |
| 2 BTU/(h·ft²) | 6.3092 W/m² |
| 3 BTU/(h·ft²) | 9.4638 W/m² |
| 4 BTU/(h·ft²) | 12.618 W/m² |
| 5 BTU/(h·ft²) | 15.773 W/m² |
| 6 BTU/(h·ft²) | 18.928 W/m² |
| 7 BTU/(h·ft²) | 22.082 W/m² |
| 8 BTU/(h·ft²) | 25.237 W/m² |
| 9 BTU/(h·ft²) | 28.391 W/m² |
| 10 BTU/(h·ft²) | 31.546 W/m² |
| 15 BTU/(h·ft²) | 47.319 W/m² |
| 20 BTU/(h·ft²) | 63.092 W/m² |
| 25 BTU/(h·ft²) | 78.865 W/m² |
| 30 BTU/(h·ft²) | 94.638 W/m² |
| 40 BTU/(h·ft²) | 126.18 W/m² |
| 50 BTU/(h·ft²) | 157.73 W/m² |
| 75 BTU/(h·ft²) | 236.59 W/m² |
| 100 BTU/(h·ft²) | 315.46 W/m² |
| 250 BTU/(h·ft²) | 788.65 W/m² |
| 500 BTU/(h·ft²) | 1,577.3 W/m² |
| 1,000 BTU/(h·ft²) | 3,154.6 W/m² |
Related conversions
Frequently asked questions
How do I convert BTU per hour square foot to watts per square metre?
Use W/m² = BTU/(h·ft²) × 3.154590745. Multiply the value in BTU per hour square foot by 3.154590745.
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.
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.
What is 10 BTU/(h·ft²) in W/m²?
10 BTU per hour square foot = 31.546 watts per square metre.
What is a BTU per hour square foot?
IT BTU basis: ≈ 3.154 591 W/m².
What is a watt per square metre?
SI unit of heat flux (and irradiance). Solar irradiance at ground ≈ 1 000 W/m².
Formula: W/m² = BTU/(h·ft²) × 3.154590745. Factors last reviewed 2026-10-27.