Understanding BTU per Hour-Foot-Degree Fahrenheit to Calories per Second-Centimetre-Degree Celsius Conversion
BTU/(h·ft·°F) is an imperial thermal-conductivity unit based on a one-foot thickness, used in process and mechanical engineering. cal/(s·cm·°C) is a CGS thermal-conductivity unit common in older physics and materials-science references. Converting between them reconciles imperial industrial data with legacy CGS conductivity tables.
Conversion Formula
To convert BTU per Hour-Foot-Degree Fahrenheit to Calories per Second-Centimetre-Degree Celsius, multiply by this factor:
Step-by-Step Example
Convert 25 BTU per Hour-Foot-Degree Fahrenheit to Calories per Second-Centimetre-Degree Celsius.
How to Convert BTU per Hour-Foot-Degree Fahrenheit to Calories per Second-Centimetre-Degree Celsius
Convert a foot-basis imperial conductivity into legacy CGS units with one multiplication.
- Start with the imperial value: Note conductivity in BTU/(h·ft·°F).
- Multiply by 0.004136555: This gives calories per second-centimetre-degree Celsius.
- Preserve precision: Retain several significant figures for downstream use.
- Report the result: cal/(s·cm·°C).
BTU per Hour-Foot-Degree Fahrenheit to Calories per Second-Centimetre-Degree Celsius conversion table
| BTU per Hour-Foot-Degree Fahrenheit (BTU/(h-ft-°F)) | Calories per Second-Centimetre-Degree Celsius (cal/(s-cm-°C)) |
|---|---|
| 0 | 0 |
| 1 | 0.004136555 |
| 2 | 0.00827311 |
| 3 | 0.01240967 |
| 4 | 0.01654622 |
| 5 | 0.02068278 |
| 6 | 0.02481933 |
| 7 | 0.02895589 |
| 8 | 0.03309244 |
| 9 | 0.037229 |
| 10 | 0.04136555 |
| 15 | 0.06204833 |
| 20 | 0.0827311 |
| 25 | 0.1034139 |
| 30 | 0.1240967 |
| 40 | 0.1654622 |
| 50 | 0.2068278 |
| 60 | 0.2481933 |
| 70 | 0.2895589 |
| 80 | 0.3309244 |
| 90 | 0.37229 |
| 100 | 0.4136555 |
| 150 | 0.6204833 |
| 200 | 0.827311 |
| 250 | 1.034139 |
| 300 | 1.240967 |
| 400 | 1.654622 |
| 500 | 2.068278 |
| 600 | 2.481933 |
| 700 | 2.895589 |
| 800 | 3.309244 |
| 900 | 3.7229 |
| 1000 | 4.136555 |
| 2000 | 8.27311 |
| 3000 | 12.40967 |
| 4000 | 16.54622 |
| 5000 | 20.68278 |
| 10000 | 41.36555 |
| 25000 | 103.4139 |
| 50000 | 206.8278 |
| 100000 | 413.6555 |
| 250000 | 1034.139 |
| 500000 | 2068.278 |
| 1000000 | 4136.555 |
What is the BTU per Hour-Foot-Degree Fahrenheit?
The BTU per hour-foot-degree Fahrenheit is the customary unit of thermal conductivity in the United States and other imperial-using industries. It measures the heat, in British thermal units per hour, conducted through a material one foot thick for each degree Fahrenheit of temperature difference.
Definition
One BTU per hour-foot-degree Fahrenheit corresponds to a heat flow of one BTU per hour through a one-foot thickness for a one-degree-Fahrenheit temperature difference. In coherent SI units:
The exact value depends on the definition of the British thermal unit used; based on the International Table BTU (1055.05585262 J), 1 BTU/(h·ft·°F) = 1.730734666 W/(m·K).
Origin and History
The unit is built from three imperial and customary quantities: the British thermal unit (the heat needed to raise one pound of water by one degree Fahrenheit), the foot, and the Fahrenheit degree. It became the standard for U.S. thermal-property data long before SI was widely adopted and persists in North American engineering practice.
Law and Notable Facts
While the SI watt per metre-kelvin is preferred internationally, BTU/(h·ft·°F) remains entrenched in U.S. mechanical, HVAC and building codes. A useful benchmark: pure copper conducts at about 231 BTU/(h·ft·°F), roughly 400 times better than the fibreglass batts used to insulate walls.
Real-World Examples and Conversions
- Structural steel is about 26 BTU/(h·ft·°F); concrete roughly 0.8–1.0.
- Water conducts at about 0.35 BTU/(h·ft·°F).
- 1 BTU/(h·ft·°F) ≈ 1.7307 W/(m·K) ≈ 1730.7 mW/(m·K).
- Conversely, 1 W/(m·K) ≈ 0.5778 BTU/(h·ft·°F).
What is the Calorie per Second-Centimetre-Degree Celsius?
The calorie per second-centimetre-degree Celsius is the CGS-based unit of thermal conductivity, historically common in physics and physical-chemistry literature. It measures the heat in calories flowing per second through a one-centimetre thickness for each degree Celsius of temperature difference.
Definition
One calorie per second-centimetre-degree Celsius represents a heat flow of one calorie per second through a one-centimetre cube per degree Celsius across it. Using the thermochemical calorie (4.184 J):
The value follows from 4.184 J/s per (0.01 m · 1 K) = 4.184 ÷ 0.01 = 418.4 W/(m·K). If the International Table calorie (4.1868 J) is used instead, the factor is 418.68 W/(m·K).
Origin and History
The unit arose in the CGS era, when heat was measured in calories, lengths in centimetres and temperature in degrees Celsius. It appears throughout older thermal-conductivity tables and heat-transfer texts, especially in chemistry and metallurgy, before the watt per metre-kelvin became standard.
Law and Notable Facts
Though largely superseded by SI, the unit is still encountered in legacy data and some scientific traditions. Its large size is convenient for metals: because 1 cal/(s·cm·°C) equals 418.4 W/(m·K), even highly conductive copper is under 1 in these units, whereas most materials are small fractions.
Real-World Examples and Conversions
- Copper conducts at about 0.94 cal/(s·cm·°C), i.e. roughly 400 W/(m·K).
- Iron is about 0.18 cal/(s·cm·°C).
- Water is roughly 0.0014 cal/(s·cm·°C).
- 1 cal/(s·cm·°C) = 418.4 W/(m·K); conversely 1 W/(m·K) ≈ 0.00239 cal/(s·cm·°C).
Frequently Asked Questions
How many cal/(s·cm·°C) is one BTU/(h·ft·°F)?
One BTU/(h·ft·°F) equals about 0.004136555 cal/(s·cm·°C).
How do I convert back to the imperial unit?
Multiply the CGS value by 241.7471 to return to BTU/(h·ft·°F).
Why is this factor twelve times the inch-basis one?
Because BTU/(h·ft·°F) is 12 times BTU-in/(h·ft²·°F), its CGS equivalent is likewise 12 times larger (0.004136555 versus 0.0003447129).
Where do CGS conductivity values still appear?
In classic metallurgical and physics tables compiled before SI adoption, where thermal conductivity is listed in cal/(s·cm·°C).
What is 25 BTU/(h·ft·°F) in CGS units?
25 BTU/(h·ft·°F) equals 0.1034139 cal/(s·cm·°C).
People also convert
Complete BTU per Hour-Foot-Degree Fahrenheit conversion table
| Unit | Result |
|---|---|
| Watts per Metre-Kelvin (W/(m-K)) | 1.730735 W/(m-K) |
| Milliwatts per Metre-Kelvin (mW/(m-K)) | 1730.735 mW/(m-K) |
| BTU-Inch per Hour-Square Foot-Degree Fahrenheit (BTU-in/(h-ft2-°F)) | 12 BTU-in/(h-ft2-°F) |
| Calories per Second-Centimetre-Degree Celsius (cal/(s-cm-°C)) | 0.004136555 cal/(s-cm-°C) |