Convert US R-Value to m²·h·°C/kcal
1 US R-value (ft²·°F·h/BTU) = 0.2048161436 square metre hour degree Celsius per kilocalorie (m²·h·°C/kcal). 1 m²·h·°C/kcal = 4.882427636 ft²·°F·h/BTU. Example: 15 ft²·°F·h/BTU = 15 × 0.2048161436 = 3.072242154 m²·h·°C/kcal.
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1 ft²·°F·h/BTU = 0.2048161436 m²·h·°C/kcal
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk R (US) to square metre hour degree Celsius per kilocalorie converter to paste a column from Excel.
How to Convert US R-Value to Square Metre Hour Degree Celsius per Kilocalorie
- 1 ft²·°F·h/BTU = 0.2048161436 m²·h·°C/kcal
- 1 m²·h·°C/kcal = 4.882427636 ft²·°F·h/BTU
- Example: convert 15 ft²·°F·h/BTU to m²·h·°C/kcal: 15 ft²·°F·h/BTU = 15 × 0.2048161436 m²·h·°C/kcal = 3.072242154 m²·h·°C/kcal
Reference conditions. m²·h·°C/kcal: International Table kilocalorie (4186.8 J).
Formula
m²·h·°C/kcal = ft²·°F·h/BTU × 0.2048161436225
or m²·h·°C/kcal = ft²·°F·h/BTU ÷ 4.882427636383
Derivation from SI units:
- 1 ft²·°F·h/BTU_IT = 0.09290304 m² × (5/9) K × 3600 s ÷ 1055.05585262 J ≈ 0.17611 m²·K/W.
- 1 m²·h·°C/kcal_IT = 3600 s ÷ 4186.8 J × m²·K ≈ 0.85985 m²·K/W.
- 1 ft²·°F·h/BTU = 0.1761101836823 m²·K/W ÷ 0.859845227859 m²·K/W per m²·h·°C/kcal = 0.2048161436225 m²·h·°C/kcal
Both units are defined exactly, so the factor is exact. US R-Value definition: US R-value; Square Metre Hour Degree Celsius per Kilocalorie definition: square metre hour degree Celsius per kilocalorie.
Worked examples
- A reading of 11 ft²·°F·h/BTU converts to 2.25297758 m²·h·°C/kcal.
11 ft²·°F·h/BTU × 0.2048161436 = 2.25297758 m²·h·°C/kcal - A value of 21 ft²·°F·h/BTU is 4.301139016 m²·h·°C/kcal.
21 ft²·°F·h/BTU × 0.2048161436 = 4.301139016 m²·h·°C/kcal
US R-Value to Square Metre Hour Degree Celsius per Kilocalorie conversion table
| US R-Value (ft²·°F·h/BTU) | Square Metre Hour Degree Celsius per Kilocalorie (m²·h·°C/kcal) |
|---|---|
| 1 ft²·°F·h/BTU | 0.2048161436 m²·h·°C/kcal |
| 3 ft²·°F·h/BTU | 0.6144484309 m²·h·°C/kcal |
| 5 ft²·°F·h/BTU | 1.024080718 m²·h·°C/kcal |
| 11 ft²·°F·h/BTU | 2.25297758 m²·h·°C/kcal |
| 13 ft²·°F·h/BTU | 2.662609867 m²·h·°C/kcal |
| 19 ft²·°F·h/BTU | 3.891506729 m²·h·°C/kcal |
| 21 ft²·°F·h/BTU | 4.301139016 m²·h·°C/kcal |
| 30 ft²·°F·h/BTU | 6.144484309 m²·h·°C/kcal |
| 38 ft²·°F·h/BTU | 7.783013458 m²·h·°C/kcal |
| 49 ft²·°F·h/BTU | 10.03599104 m²·h·°C/kcal |
Where it's used
US R-Value are used for US insulation labels (R-13, R-19, R-38), while square metre hour degree Celsius per kilocalorie appear in older building-physics texts and IS codes. Both measure thermal resistance per unit area (insulation R-value), so the conversion is a fixed factor.
US R-Value to other thermal resistance (r-value) units
| Conversion | 1 ft²·°F·h/BTU equals |
|---|---|
| R (US) to square metre hour degree Celsius per kilocalorie | 0.2048161436 m²·h·°C/kcal |
| R (US) to RSI | 0.1761101837 m²·K/W |
| R (US) to clo | 1.136194733 clo |
| R (US) to tog | 1.761101837 tog |
Frequently asked questions
How many square metre hour degree Celsius per kilocalorie are in 1 US R-value?
1 ft²·°F·h/BTU = 0.2048161436 m²·h·°C/kcal.
How do I convert US R-value to square metre hour degree Celsius per kilocalorie?
Multiply the value in ft²·°F·h/BTU by 0.2048161436, or divide it by 4.882427636. For example, 15 ft²·°F·h/BTU × 0.2048161436 = 3.072242154 m²·h·°C/kcal.
Is the ft²·°F·h/BTU to m²·h·°C/kcal conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "degree Fahrenheit hour square foot per British thermal unit_IT".
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "calorie_IT".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert US R-Value to m²·h·°C/kcal. Retrieved October 29, 2026, from https://scientificconverters.com/thermal-resistance/r-value-to-square-meter-hour-celsius-per-kilocalorie/
IEEE
Scientific Converters, "Convert US R-Value to m²·h·°C/kcal," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/thermal-resistance/r-value-to-square-meter-hour-celsius-per-kilocalorie/