British Thermal Units to Calories Converter

One British Thermal Unit equals 252.1644007 Calories (1 BTU = 252.1644007 cal). Multiply a British Thermal Unit value by 252.1644007 to get the equivalent in Calories. Use the calculator above for your value, or check the 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 Calories.

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)
0.125.21644007
0.5126.0822004
1252.1644007
2504.3288014
51260.822004
102521.644007
256304.110018
5012608.22004
10025216.44007
25063041.10018
500126082.2004
1000252164.4007

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 Units × 252.1644007 = 2521.644007 Calories.
  4. Label the result as Calorie (cal).

Relative Size Comparison

1 British Thermal Unit
1 BTU
1 Calorie0.003965666831 British 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 under the thermochemical convention. It originally described 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 Calories (1 BTU = 252.1644007 cal). British Thermal Unit is used in air conditioner and furnace ratings in the US and in US natural gas appliance specs. Calorie is used in 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

15British Thermal Units equals3782.466011Calories.

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 Calories.

What is the formula for British Thermal Unit to Calorie?

The formula is cal = BTU × 252.1644007.

How many Calories are in 1 British Thermal Unit?

1 British Thermal Unit equals 252.1644007 Calories.

Can I convert Calorie back to British Thermal Unit?

Yes. 1 Calorie equals 0.003965666831 British Thermal Units, 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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