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Heat Transfer

BTU/(hr·ft²)toW/m²

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

Factor1 BTU/(hr·ft²) = 3.154591 W/m²

Converter

BTU/(hr·ft²)

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

Result
315.459W/m²

Rendered to 6 significant figures.

Formula

Formula
W/m² = BTU/(hr·ft²) × 3.154591

Multiply any value in British thermal units per hour-square foot by 3.154591 to obtain the value in watts per square metre.

Worked example

Convert 100 BTU/(hr·ft²) to W/m².

  1. 01Start with 100 BTU/(hr·ft²).
  2. 02Multiply by the conversion factor: 100 × 3.154591 = 315.459 W/m².
Result100 BTU/(hr·ft²) = 315.459 W/m²

Conversion table

BTU/(hr·ft²)W/m²
13.1546
26.3092
515.773
1031.546
2063.092
50157.73
100315.46
200630.92
5001577.3
10003154.6

Reference values rounded to 5 significant figures for display.

FAQ

What is the conversion factor from BTU/(hr·ft²) to W/m²?
1 BTU/(hr·ft²) equals 3.154591 W/m². To convert, multiply the value in British thermal units per hour-square foot by 3.154591.
How do I convert 1 BTU/(hr·ft²) to W/m²?
1 BTU/(hr·ft²) = 3.15459 W/m². For any value, multiply by 3.154591.
How do I convert W/m² back to BTU/(hr·ft²)?
Divide by the same factor — or equivalently, multiply by 0.3169983. So 1 W/m² = 0.316998 BTU/(hr·ft²).
When would I need to convert British thermal unit per hour-square foot to watt per square metre?
Heat-flux conversions between BTU/(hr·ft²) and W/m² 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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