BTU to Joules Converter

BTU to Joules

Convert btu (BTU) to joules (J). Both measure work and power, and the conversion comes up in nutrition, electricity, fitness work.

The Formula

`` joules = btu × 1055.05585262 btu = joules × 0.000947817120313 `

One BTU is 1,055.06 joules, and one joule is 9.4782e-4 btu.

Conversion Table

BTU	Joules
1 BTU	1,055.06 J
2 BTU	2,110.11 J
5 BTU	5,275.28 J
10 BTU	10,550.56 J
25 BTU	26,376.4 J
50 BTU	52,752.79 J
100 BTU	105,505.59 J
500 BTU	527,527.93 J
1,000 BTU	1,055,055.85 J

The Other Direction

Joules	BTU
1 J	9.4782e-4 BTU
2 J	0.001896 BTU
5 J	0.004739 BTU
10 J	0.009478 BTU
25 J	0.023695 BTU
50 J	0.047391 BTU
100 J	0.094782 BTU
500 J	0.473909 BTU
1,000 J	0.947817 BTU

What Each Unit Is

BTU (BTU) — the energy to raise one pound of water by one degree Fahrenheit, or 1,055 joules. The imperial thermal unit, still standard for US heating, cooling and gas.

Joules (J) — the work done by one newton acting over one metre — the SI derived unit of energy. Named for James Prescott Joule, who established the mechanical equivalent of heat.

A Sense of Scale

• A window air conditioner is 5,000–12,000 BTU/h
• US furnaces are rated in BTU
• Lifting an apple one metre takes about 1 J
• A heartbeat uses roughly 1 J

Precision

The factor 1055.05585262 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.

In Code

`javascript const btuToJoule = (value) => value * 1055.05585262; ``

Where This Conversion Comes Up

• Nutrition
• Electricity
• Fitness
• Heating
• Fuel

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 BTU with the factor truncated at each decimal place:

Decimals kept	Factor	137 BTU becomes	Error
0	1055	144,535	0.0053%
1	1055.1	144,548.7	0.0042%
2	1055.06	144,543.22	0.0004%
3	1055.056	144,542.67	—
4	1055.0559	144,542.66	—

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured btu to three significant figures, the answer in joules is only good to three — writing more digits claims precision the measurement never had.