Convert BTU per Hour to Calories per Second
BTU per Hour (BTU/h) to Calorie per Second (cal/s) unit conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 BTU/h = 0.069998823 cal/s
1 BTU per Hour = 0.069998823 Calories per Second
1 Calorie per Second = 14.285955 BTU per Hour
1 BTU/h in every supported unit
Conversion chart: BTU per Hour to Calories per Second
Conversion table
| BTU per Hour (BTU/h) | Calorie per Second (cal/s) |
|---|---|
| 0.01 BTU/h | 0.00069998823 cal/s |
| 0.1 BTU/h | 0.0069998823 cal/s |
| 1 BTU/h | 0.069998823 cal/s |
| 2 BTU/h | 0.13999765 cal/s |
| 3 BTU/h | 0.20999647 cal/s |
| 5 BTU/h | 0.34999411 cal/s |
| 10 BTU/h | 0.69998823 cal/s |
| 20 BTU/h | 1.3999765 cal/s |
| 50 BTU/h | 3.4999411 cal/s |
| 100 BTU/h | 6.9998823 cal/s |
| 1000 BTU/h | 69.998823 cal/s |
BTU per Hour (BTU/h)
Definition: The rate of energy transfer equal to one British Thermal Unit (the heat needed to raise one pound of water by one degree Fahrenheit) per hour, equal to about 0.293 watts.
History: Derived from the British Thermal Unit, a 19th-century imperial heat-energy unit used throughout British and American engineering before the widespread adoption of the metric system's joule.
Current use: The standard unit for rating the heating and cooling capacity of air conditioners, furnaces, and boilers in the United States HVAC industry.
Calorie per Second (cal/s)
Definition: The rate of transferring one (small) calorie of heat energy — the energy needed to raise one gram of water by one degree Celsius — every second, equal to exactly 4.1868 watts.
History: Derived from the calorie, a unit of heat energy defined in the early 19th century by French physicist Nicolas Clément, later tied exactly to the joule (1 cal = 4.1868 J) once the SI system was established.
Current use: Occasionally used in thermal and biological contexts, such as expressing metabolic power output or heat-transfer rates in laboratory and physiology settings, where energy is already tracked in calories.
Supported Units
| Unit | Symbol | In Watts |
|---|---|---|
| Milliwatt | mW | 0.001 W |
| Watt | W | 1 W |
| Kilowatt | kW | 1000 W |
| Megawatt | MW | 1000000 W |
| Gigawatt | GW | 1E+09 W |
| Horsepower (mechanical) | hp | 745.69987 W |
| Horsepower (metric) | PS | 735.49875 W |
| BTU per Hour | BTU/h | 0.29307107 W |
| Foot-pound per Second | ft·lb/s | 1.3558179 W |
| Calorie per Second | cal/s | 4.1868 W |
About These Parameters
- Value
- The number you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The unit your input value is currently measured in.
- To Unit
- The unit you want the result converted into. Use the swap button to flip From and To instantly.
How Power Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to the watt. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For BTU per Hour → Calorie per Second: multiply by 0.069998823. For example, 1 BTU/h × 0.069998823 = 0.069998823 cal/s.
Mechanical vs. Metric Horsepower
The two horsepower units on this page look almost identical but are not quite the same: mechanical horsepower (hp) is defined as exactly 550 foot-pounds of work per second (about 745.7 W) and is the standard for cars and engines in the US and UK, while metric horsepower (PS, from the German Pferdestärke) is defined as the power to lift 75 kilograms one meter per second (about 735.5 W) and is used across continental Europe, Japan, and much of Asia. The difference is small — about 1.4% — but it means a car advertised as "300 PS" in Germany produces slightly less power than a car advertised as "300 hp" in the US, even though the numbers look the same.
How James Watt Defined Horsepower
In the 1780s, engineer James Watt needed a way to convince mill owners that his improved steam engines could outperform the horses they already used to turn grinding wheels. He observed a strong horse turning a mill and calculated it could sustain roughly 33,000 foot-pounds of work per minute — equivalent to 550 foot-pounds per second — and fixed that figure as "one horsepower." The unit stuck long after steam engines and horses both gave way to electric and internal combustion power, and it remains the standard way vehicle and engine power is marketed today.
Example
1 BTU/h equals 0.069998823 cal/s. For scale, that's about 0× the power draw of a typical microwave oven (1,000 W, or 3412.1416 BTU/h).
Frequently Asked Questions
How many Calories per Second are in 1 BTU per Hour?
1 BTU per Hour (BTU/h) equals exactly 0.069998823 Calories per Second (cal/s).
Why are there two kinds of horsepower?
Mechanical horsepower (550 ft·lb/s, about 745.7 W) was defined in Britain by James Watt in the 1780s, while metric horsepower (PS, about 735.5 W) was defined later in continental Europe using kilograms and meters instead of pounds and feet. Both describe roughly "the power of a horse," but because they were defined with different unit systems the two figures differ by about 1.4%.
How many watts is 1 horsepower?
1 mechanical horsepower equals exactly 745.6998715823 watts (about 745.7 W), while 1 metric horsepower (PS) equals exactly 735.49875 watts (about 735.5 W). Both are close to but not the same as 1 kilowatt (1,000 W).
How accurate are these conversions?
Every conversion factor used here is the exact, internationally recognized value (e.g. 1 hp = exactly 745.6998715823 W, 1 PS = exactly 735.49875 W) — results are limited only by floating-point display precision, not by rounded conversion constants.