Convert kilojoule to BTU.

Convert kilojoule (kJ) to BTU (BTU). This is a fixed-ratio conversion — multiply the input by the factor below.

Formula

BTU = kJ × 0.947817

Reference values

Things to watch for

• The 'calorie' in nutrition labels is actually a kilocalorie (kcal, sometimes Cal with capital C). A '200 calorie' candy bar is 200 kcal = 836 kJ.
• 1 kWh = 3.6 MJ (exactly). Used for billing electricity.
• Electron-volts (eV) are convenient at atomic/molecular scales; joules at human scales; kWh at building scales.

What is a kilojoule?

One kilojoule equals exactly 1,000 joules. Food energy labels in Europe and Australia (an apple is about 200 kJ), thermal calculations.

What is a British thermal unit?

One BTU equals about 1,055.06 joules — the energy to raise one pound of water by 1°F. HVAC (air conditioner ratings, e.g. 12,000 BTU/h = 1 ton), natural gas heating, and US heating equipment.

Everyday reference points for kJ

Here are a few familiar reference points to gauge the unit. 1 kJ is the energy to lift a 100 kg adult one meter; 100 kJ is a chocolate-bar food label; and 2000 kJ is a typical meal's energy.

How to convert kilojoule to British thermal unit

To convert a value from kilojoule (kJ) to British thermal unit (BTU), apply the conversion factor shown in the formula above. The calculation is the same whether you do it by hand, in a spreadsheet, or with the live converter on this page.

Steps:

1. Take your input value in kJ.
2. Apply the formula BTU = kJ × 0.947817.
3. The result is your value in BTU.

For repeated calculations, save the formula in a spreadsheet or use the live converter at the top of this page — it handles the math automatically and displays the result as you type.

Frequently asked questions

How do I convert kJ to BTU?

Apply the formula kJ → BTU shown above, or just type your value into the converter at the top of this page. The result updates instantly.

Which is bigger, kJ or BTU?

This depends on the conversion ratio in the formula. If the factor multiplied by your value gives a larger number, then BTU is the smaller unit (so it takes more of them to express the same quantity). If the result is smaller, then BTU is the larger unit.

When would I use kJ versus BTU?

Both units measure energy, so the choice depends on context. Kilojoule is typically used for food labeling, batteries, fuel, and electric utility billing; British thermal unit similarly. Most professional fields standardize on one or the other based on regional conventions or technical tradition.

How precise is this kJ to BTU conversion?

The conversion factor shown is the internationally defined exact value (or the best-published approximation if the relationship is irrational, like degrees-to-radians). The live converter on this page uses double-precision floating-point math, accurate to about 15 significant digits — far beyond any practical engineering need.

Is the conversion ratio exact, or an approximation?

Most unit conversions between SI metric units, and between SI and US customary units, have been formally defined as exact values since the 1959 international yard-pound agreement and subsequent SI redefinitions. Exceptions are unit pairs that involve irrational numbers (radians, e.g.) or empirical conversions (like food calories, which depend on temperature). When in doubt, consult the formula at the top of this page.

Related conversions

See also