Convert US R-Value to Clo (ft2 F h/BTU to clo)
1 US R-value (ft²·°F·h/BTU) = 1.136194733 clo. 1 clo = 0.8801308179 ft²·°F·h/BTU. Example: 15 ft²·°F·h/BTU = 15 × 1.136194733 = 17.042921 clo.
Also searched as US R-value to clo, US R-value in clo, US R-value into clo, ft2 F h/BTU to clo, ft2 F h/BTU in clo, ft2 F h/BTU into clo, ft2 F h/BTU to clo converter and how many clo in a US R-value.
1 ft²·°F·h/BTU = 1.136194733 clo
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk R (US) to clo converter to paste a column from Excel.
How to Convert US R-Value to Clo
- 1 ft²·°F·h/BTU = 1.136194733 clo
- 1 clo = 0.8801308179 ft²·°F·h/BTU
- Example: convert 15 ft²·°F·h/BTU to clo: 15 ft²·°F·h/BTU = 15 × 1.136194733 clo = 17.042921 clo
Formula
clo = ft²·°F·h/BTU × 1.136194733434
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 clo = 0.155 m²·K/W (ISO 7730, ASHRAE 55).
- 1 ft²·°F·h/BTU = 0.1761101836823 m²·K/W ÷ 0.155 m²·K/W per clo = 1.136194733434 clo
Both units are defined exactly, so the factor is exact. US R-Value definition: US R-value; Clo definition: clo.
Worked examples
- A reading of 11 ft²·°F·h/BTU converts to 12.49814207 clo.
11 ft²·°F·h/BTU × 1.136194733 = 12.49814207 clo - A value of 21 ft²·°F·h/BTU is 23.8600894 clo.
21 ft²·°F·h/BTU × 1.136194733 = 23.8600894 clo
US R-Value to Clo conversion table
| US R-Value (ft²·°F·h/BTU) | Clo |
|---|---|
| 1 ft²·°F·h/BTU | 1.136194733 clo |
| 3 ft²·°F·h/BTU | 3.4085842 clo |
| 5 ft²·°F·h/BTU | 5.680973667 clo |
| 11 ft²·°F·h/BTU | 12.49814207 clo |
| 13 ft²·°F·h/BTU | 14.77053153 clo |
| 19 ft²·°F·h/BTU | 21.58769994 clo |
| 21 ft²·°F·h/BTU | 23.8600894 clo |
| 30 ft²·°F·h/BTU | 34.085842 clo |
| 38 ft²·°F·h/BTU | 43.17539987 clo |
| 49 ft²·°F·h/BTU | 55.67354194 clo |
Where it's used
US R-Value are used for US insulation labels (R-13, R-19, R-38), while clo appear in thermal comfort (PMV/PPD) in ASHRAE 55 and ISO 7730. 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 clo | 1.136194733 clo |
| R (US) to RSI | 0.1761101837 m²·K/W |
| R (US) to tog | 1.761101837 tog |
| R (US) to square metre hour degree Celsius per kilocalorie | 0.2048161436 m²·h·°C/kcal |
Frequently asked questions
How many clo are in 1 US R-value?
1 ft²·°F·h/BTU = 1.136194733 clo.
How do I convert US R-value to clo?
Multiply the value in ft²·°F·h/BTU by 1.136194733. For example, 15 ft²·°F·h/BTU × 1.136194733 = 17.042921 clo.
Is the ft²·°F·h/BTU to clo 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, "clo".
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 Clo (ft2 F h/BTU to clo). Retrieved October 29, 2026, from https://scientificconverters.com/thermal-resistance/r-value-to-clo/
IEEE
Scientific Converters, "Convert US R-Value to Clo (ft2 F h/BTU to clo)," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/thermal-resistance/r-value-to-clo/