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Heat Transfer

W/m²toBTU/(hr·ft²)

Convert watts per square metre (W/m²) to British thermal units per hour-square foot (BTU/(hr·ft²)).

Factor1 W/m² = 0.3169983 BTU/(hr·ft²)

Converter

W/m²

Accepts numbers or expressions, e.g. 150 + 14.7

Result
316.998BTU/(hr·ft²)

Rendered to 6 significant figures.

Formula

Formula
BTU/(hr·ft²) = W/m² × 0.3169983

Multiply any value in watts per square metre by 0.3169983 to obtain the value in British thermal units per hour-square foot.

Worked example

Convert 1000 W/m² to BTU/(hr·ft²).

  1. 01Start with 1000 W/m².
  2. 02Multiply by the conversion factor: 1000 × 0.3169983 = 316.998 BTU/(hr·ft²).
Result1000 W/m² = 316.998 BTU/(hr·ft²)

Conversion table

W/m²BTU/(hr·ft²)
10.317
20.634
51.585
103.17
206.34
5015.85
10031.7
20063.4
500158.5
1000317

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from W/m² to BTU/(hr·ft²)?
1 W/m² equals 0.3169983 BTU/(hr·ft²). To convert, multiply the value in watts per square metre by 0.3169983.
How do I convert 1 W/m² to BTU/(hr·ft²)?
1 W/m² = 0.316998 BTU/(hr·ft²). For any value, multiply by 0.3169983.
How do I convert BTU/(hr·ft²) back to W/m²?
Divide by the same factor — or equivalently, multiply by 3.154591. So 1 BTU/(hr·ft²) = 3.15459 W/m².
When would I need to convert watt per square metre to British thermal unit per hour-square foot?
Heat-flux conversions between W/m² and BTU/(hr·ft²) appear in radiative-heat-transfer analysis, furnace and reactor design, electronics cooling, and solar-energy calculations. W/m² is the SI standard; BTU/(hr·ft²) and kcal/(hr·m²) appear in US and legacy European datasheets.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).

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