British Thermal Unit to Calorie Converter

One British Thermal Unit equals 252.1644007 Calorie (1 BTU = 252.1644007 cal). Multiply a British Thermal Unit value by 252.1644007 to get the equivalent in Calorie. Use the calculator above for instant results, or follow the formula, worked examples, and reference table below.

Formula

cal = BTU × 252.1644007

Multiply the British Thermal Unit value by 252.1644007 to get the equivalent value in Calorie.

Example Conversions

1 British Thermal Unit (BTU)

252.1644007 Calorie (cal)

5 British Thermal Unit (BTU)

1260.822004 Calorie (cal)

10 British Thermal Unit (BTU)

2521.644007 Calorie (cal)

25 British Thermal Unit (BTU)

6304.110018 Calorie (cal)

100 British Thermal Unit (BTU)

25216.44007 Calorie (cal)

Conversion Table

Common conversion values from British Thermal Unit to Calorie
British Thermal Unit (BTU) Calorie (cal)
0.1 25.21644007
0.5 126.0822004
1 252.1644007
2 504.3288014
5 1260.822004
10 2521.644007
25 6304.110018
50 12608.22004
100 25216.44007
250 63041.10018
500 126082.2004
1000 252164.4007

How to Convert Manually

Use these steps to convert British Thermal Unit values to Calorie without the calculator.

  1. Write down the value in British Thermal Unit (BTU) that you want to convert.
  2. Multiply that value by 252.1644007.
  3. For example, 10 British Thermal Unit × 252.1644007 = 2521.644007 Calorie.
  4. Label the result as Calorie (cal).

Relative Size Comparison

1 British Thermal Unit
1BTU
1 Calorie0.003965666831British Thermal Units

This chart shows the visual difference in size between exactly one British Thermal Unit and one Calorie.

About British Thermal Unit and Calorie

The British thermal unit is about 1,055.06 joules — the heat to raise one pound of water by 1 °F. US heating and cooling equipment is rated in BTU per hour. The calorie (small calorie) is exactly 4.184 joules — the thermochemical convention, originally the heat to warm one gram of water by 1 °C. Chemistry uses it; food 'Calories' are actually kilocalories. One British Thermal Unit equals 252.1644007 Calorie (1 BTU = 252.1644007 cal). British Thermal Unit to Calorie conversion comes up most often in air conditioner and furnace ratings in the US and in US natural gas appliance specs, typically when figures need restating for chemistry heat calculations.

Precision and Rounding: Energy factors mix exact definitions (1 kWh = 3,600,000 J; 1 cal = 4.184 J thermochemical) with measured conventions (1 BTU ≈ 1,055.056 J). Nutrition and utility bills round to whole units; engineering heat calculations should keep the full factor until the final step.

Conversion factors per NIST Special Publication 811 and the BIPM SI Brochure (9th edition) (reference).

Worked Example

15 British Thermal Unit equals 3782.466011 Calorie.

15 BTU × 252.1644007 = 3782.466011 cal

FAQ

How do I convert British Thermal Unit to Calorie?

Multiply the British Thermal Unit value by 252.1644007 to get the equivalent value in Calorie.

What is the formula for British Thermal Unit to Calorie?

The formula is cal = BTU × 252.1644007.

How many Calorie are in 1 British Thermal Unit?

1 British Thermal Unit equals 252.1644007 Calorie.

Can I convert Calorie back to British Thermal Unit?

Yes. 1 Calorie equals 0.003965666831 British Thermal Unit, and the related converter can reverse the calculation.

What are common names for British Thermal Unit and Calorie?

British Thermal Unit is shown as BTU and may also be searched as btu, british thermal unit. Calorie is shown as cal and may also be searched as calorie, calories, small calorie.

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