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Energy

Convert BTU to kilojoules

1 BTU=1.05506kJ

Use the converter below to change any BTU value into kilojoules instantly — with formula, conversion table, and real-world examples.

1.055056

Conversion formula

Forward
kilojoules = BTU × 1.05506
Reverse
BTU = kilojoules × 0.9478

Example: 10 BTU × 1.05506 = 10.5506 kJ.

About both units

From

British Thermal Unit

BTU

The British Thermal Unit equals approximately 1055 joules — the energy to raise 1 pound of water by 1 °F. Used for HVAC, heating, and air-conditioning capacity in the US. A 9000 BTU/h AC is a small room unit.

Real-world: Window AC: 5000–12,000 BTU/h. Central AC: 24,000–60,000 BTU/h. Home furnace: 60,000–100,000 BTU/h.
Read full british thermal unit reference →
To

Kilojoule

kJ

The kilojoule equals 1000 joules. Used on European nutrition labels (required by EU law alongside kcal), for mechanical work specifications, and some engineering contexts. A 100 g chocolate bar contains about 2100 kJ.

Real-world: 100 g chocolate: ~2100 kJ. EU daily intake (adult): ~8400 kJ. Tesla Model 3 battery: ~270 MJ = 270,000 kJ.
Read full kilojoule reference →

British Thermal Unit to Kilojoule conversion table

Common BTU to kilojoules values for quick reference.

British Thermal Unit (BTU)Kilojoule (kJ)
1 BTU1.05506 kJ
10 BTU10.5506 kJ
100 BTU105.506 kJ
500 BTU527.528 kJ
1,000 BTU1,055.06 kJ
5,000 BTU5,275.28 kJ
10,000 BTU10,550.56 kJ
50,000 BTU52,752.79 kJ
100,000 BTU105,505.59 kJ
500,000 BTU527,527.93 kJ

Tips & common mistakes

Quick tips

  • 1 BTU = 1055.06 J = 0.293 Wh.
  • BTU/h (power) and BTU (energy) are different — don't confuse.
  • Tons of refrigeration: 12,000 BTU/h = 1 ton AC.

Avoid these

  • Confusing BTU and BTU/h — energy vs power.
  • Using kcal when BTU is requested in HVAC specs.
  • Treating all BTUs as exact — definitions vary (IT, thermochemical, etc.).

Frequently asked questions

How many kilojoules in a british thermal unit?
One british thermal unit equals 1.05506 kilojoules.
How do I convert BTU to kilojoules?
Multiply the british thermal unit value by 1.05506 to get the equivalent in kilojoules.
What is 100 BTU in kilojoules?
100 BTU equals 105.506 kilojoules.
Is a british thermal unit bigger than a kilojoule?
Yes. 1 british thermal unit equals 1.05506 kilojoules, so one british thermal unit is larger.
How to convert BTU to kilojoules without a calculator?
Multiply by 1.06 for a quick estimate; use a calculator for precise results.

Related energy conversions

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More from British Thermal Unit

BTU → J
1 = 1,055.06 J
BTU → MJ
1 = 0.001055 MJ
BTU → kWh
1 = 0.0002931 kWh
BTU → Wh
1 = 0.2931 Wh
BTU → cal
1 = 252.164 cal
BTU → kcal
1 = 0.2522 kcal
BTU → eV
1 = 6.5851e21 eV
BTU → thm
1 = 1.0000e-5 thm

More to Kilojoule

J → kJ
1 = 0.001 kJ
MJ → kJ
1 = 1,000 kJ
kWh → kJ
1 = 3,600 kJ
Wh → kJ
1 = 3.6 kJ
cal → kJ
1 = 0.004184 kJ
kcal → kJ
1 = 4.184 kJ
eV → kJ
1 = 1.6022e-22 kJ
thm → kJ
1 = 105,505.59 kJ

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