Convert RSI (m²·K/W) to US R-Value (m2 K/W to ft2 F h/BTU)
1 square metre kelvin per watt (m²·K/W) = 5.678263341 US R-value (ft²·°F·h/BTU). 1 ft²·°F·h/BTU = 0.1761101837 m²·K/W. Example: 2.5 m²·K/W = 2.5 × 5.678263341 = 14.19565835 ft²·°F·h/BTU.
Also searched as RSI to R-value, m2K/W to US R value and metric R value to imperial.
1 m²·K/W = 5.678263341 ft²·°F·h/BTU
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk RSI to R (US) converter to paste a column from Excel.
How to Convert RSI (m²·K/W) to US R-Value
- 1 m²·K/W = 5.678263341 ft²·°F·h/BTU
- 1 ft²·°F·h/BTU = 0.1761101837 m²·K/W
- Example: convert 2.5 m²·K/W to ft²·°F·h/BTU: 2.5 m²·K/W = 2.5 × 5.678263341 ft²·°F·h/BTU = 14.19565835 ft²·°F·h/BTU
Formula
ft²·°F·h/BTU = m²·K/W × 5.678263341113
Derivation from SI units:
- Thermal resistance per unit area R = thickness ÷ conductivity, in m²·K/W; U = 1/ΣR.
- 1 ft²·°F·h/BTU_IT = 0.09290304 m² × (5/9) K × 3600 s ÷ 1055.05585262 J ≈ 0.17611 m²·K/W.
Both units are defined exactly, so the factor is exact. RSI (m²·K/W) definition: square metre kelvin per watt; US R-Value definition: US R-value.
Worked examples
- A wall rated 2.5 m²·K/W is 14.19565835 ft²·°F·h/BTU.
2.5 m²·K/W × 5.678263341 = 14.19565835 ft²·°F·h/BTU - 1 m²·K/W is 5.678263341 ft²·°F·h/BTU.
1 m²·K/W × 5.678263341 = 5.678263341 ft²·°F·h/BTU
RSI (m²·K/W) to US R-Value conversion table
| RSI (m²·K/W) (m²·K/W) | US R-Value (ft²·°F·h/BTU) |
|---|---|
| 0.1 m²·K/W | 0.5678263341 ft²·°F·h/BTU |
| 0.5 m²·K/W | 2.839131671 ft²·°F·h/BTU |
| 1 m²·K/W | 5.678263341 ft²·°F·h/BTU |
| 1.5 m²·K/W | 8.517395012 ft²·°F·h/BTU |
| 2 m²·K/W | 11.35652668 ft²·°F·h/BTU |
| 2.5 m²·K/W | 14.19565835 ft²·°F·h/BTU |
| 3 m²·K/W | 17.03479002 ft²·°F·h/BTU |
| 4 m²·K/W | 22.71305336 ft²·°F·h/BTU |
| 5 m²·K/W | 28.39131671 ft²·°F·h/BTU |
| 7 m²·K/W | 39.74784339 ft²·°F·h/BTU |
Where it's used
Metric RSI values (m²·K/W) from ECBC, Part L or EN products are converted to US R-values. Multiply by 5.67826.
RSI (m²·K/W) to other thermal resistance (r-value) units
| Conversion | 1 m²·K/W equals |
|---|---|
| RSI to R (US) | 5.678263341 ft²·°F·h/BTU |
| RSI to clo | 6.451612903 clo |
| RSI to tog | 10 tog |
| RSI to square metre hour degree Celsius per kilocalorie | 1.163 m²·h·°C/kcal |
Frequently asked questions
What is RSI 1 in US R?
RSI 1 = 5.678263341 ft²·°F·h/BTU.
How many US R-value are in 1 square metre kelvin per watt?
1 m²·K/W = 5.678263341 ft²·°F·h/BTU.
How do I convert square metre kelvin per watt to US R-value?
Multiply the value in m²·K/W by 5.678263341. For example, 2.5 m²·K/W × 5.678263341 = 14.19565835 ft²·°F·h/BTU.
Is the m²·K/W to ft²·°F·h/BTU 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
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4 (derived units with special names).
- 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".
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 RSI (m²·K/W) to US R-Value (m2 K/W to ft2 F h/BTU). Retrieved October 29, 2026, from https://scientificconverters.com/thermal-resistance/rsi-to-r-value/
IEEE
Scientific Converters, "Convert RSI (m²·K/W) to US R-Value (m2 K/W to ft2 F h/BTU)," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/thermal-resistance/rsi-to-r-value/