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BTU to Kilojoules Converter
↔ Convert kJ to BTU instead

Common Conversions

BTU kJ
0.1 0.1055
1 1.055
5 5.275
10 10.551
50 52.753
100 105.506
500 527.53
1000 1055.06
3412 3600
5000 5275.3
10000 10550.6

Why this conversion matters in chemistry

A BTU is the heat needed to warm one pound of water by one degree Fahrenheit. The kilojoule is the SI workhorse for chemistry energetics. They're in the same neighborhood — 1 BTU is 1.05506 kJ — close enough that the rough approximation "1 BTU ≈ 1 kJ" works for a quick sanity check, off by only about 5.5%. The conversion comes up most often when US-spec engineering data — boiler ratings, furnace outputs, natural-gas heating values around 1030 BTU per standard cubic foot — has to land on a chemistry calculation that runs in kJ. Multiplying by 1.05506 is the step that lets the two trade numbers without quietly losing 5%.

Formula

kJ = BTU × 1.05506

Worked Examples

1 BTU = 1.055 kJ

One BTU — slightly more than a kJ, the value that anchors every entry in the table.

100 BTU = 105.5 kJ

About the heat to warm a kilogram of water by 25 °C — a useful midscale reference for calorimetry calculations.

1000 BTU = 1055.06 kJ

Roughly 1 MJ of energy — the scale of a small-scale combustion experiment.

3412 BTU = 3600 kJ

The equivalent of one kilowatt-hour — a useful conversion when bridging facility-scale electrical energy and reaction-scale chemistry.

Frequently Asked Questions

How do I convert BTU to kJ?
Multiply by 1.05506. So 1000 BTU becomes 1055.06 kJ. The factor is exact through the IT-BTU definition.
Are BTU and kJ roughly the same?
Close. One BTU is about 1.055 kJ, off by about 5.5%. For a rough estimate, treating 1 BTU as 1 kJ gets you in the right ballpark; for a quantitative calculation you need the full factor.
Where do BTU show up in chemistry?
Mostly in US-tradition engineering applications — boiler ratings, furnace efficiencies, heat-exchanger design, fuel heating values, HVAC calculations. Reaction calorimetry and most modern thermochemistry stay in kJ, so the conversion is the bridge between the two worlds.
How many BTU in a therm?
One therm is exactly 100,000 BTU, which works out to 105,506 kJ or about 105.5 MJ. The therm is the unit US natural-gas suppliers use for residential billing — it's the energy equivalent of roughly 100 cubic feet of pipeline-quality natural gas.