How many joules in 1 BTU?
1 BTU (International Table) equals 1,055.06 joules.
Energy conversion
Joules to BTU converter calculator
Last updated:
1 BTU (International Table) equals 1,055.06 joules. To convert joules to BTU, divide by 1,055.06. 1,000 J is about 0.948 BTU; 1 MJ is 947.82 BTU.
Featured joules to btu converter answer
Joules
100 J
BTU converter
0.0948 BTU
Formula: 1 joule = 0.000947817 BTU. Open the live calculator to convert any value.
Formula
1 joule = 0.000947817 BTU
There are several historical BTU definitions; the modern standard is the IT BTU (1,055.05585262 J exactly). The 'thermochemical' BTU is 1,054.35 J, used in some older US thermodynamics references.
Common values
| From | To |
|---|---|
| 100 J | 0.0948 BTU |
| 500 J | 0.4738 BTU |
| 1,000 J (1 kJ) | 0.9478 BTU |
| 5,000 J | 4.7390 BTU |
| 10,000 J | 9.4781 BTU |
| 100,000 J | 94.78 BTU |
| 1,000,000 J (1 MJ) | 947.82 BTU |
| 10,000,000 J | 9,478 BTU |
| 100,000,000 J | 94,781 BTU |
| 1,000,000,000 J (1 GJ) | 947,817 BTU |
Background
Joules are the SI energy unit; BTU is a customary unit common in US HVAC, gas appliances, and food calories' cousin. 1 food Calorie equals 4,184 J, so a 200-Cal snack delivers about 836,800 J or 793 BTU.
Common use cases
- Translate SI energy values into BTU for heating and HVAC documentation.
- Compare appliance or system energy figures that mix joules and thermal units.
- Check engineering calculations without manually dividing by the BTU conversion factor.
Frequently asked questions
What is a BTU used for?
BTU is the customary unit for heating and cooling capacity in US HVAC. Window AC units are typically rated in BTU/hr (e.g. 8,000 BTU/hr cools roughly a 350 sq ft room).
Are food calories the same as joules or BTU?
Food calories are a different scale. 1 food Calorie (kcal) is 4,184 J or 3.966 BTU. So a 200-Cal snack equals about 836,800 J or 793 BTU.
Are there multiple BTU definitions?
Yes. The IT BTU (1,055.06 J) is standard. The thermochemical BTU (1,054.35 J) and the 'mean' BTU (1,055.87 J) appear in older references. The difference is less than 0.2%, so most everyday calculations use the IT definition.
How much energy is 1 kWh in BTU?
1 kWh equals 3,412.14 BTU. A 1,500 W space heater running for an hour consumes about 5,118 BTU of electrical energy.