BTU to Joules Converter
Convert British thermal units to joules and back, instantly.
Translate thermal energy to SI energy
British thermal units appear in heating, fuel, and appliance contexts, while joules are the SI energy unit. This page converts energy rather than a BTU-per-hour power rating. It uses the international-table BTU relationship and keeps the distinction visible so energy and equipment capacity are not accidentally mixed.
The default 1 BTU converts to 1,055.06 joules after six-significant-figure rounding. In reverse, 1,000 joules converts to 0.947817 BTU. The table supplies quick whole-BTU comparisons, but it does not account for system efficiency or heat lost to the surroundings.
Private conversion, separate from load sizing
Energy values stay in your browser and are never uploaded. The tool does not estimate building heat loss, fuel consumption, seasonal efficiency, or required HVAC capacity. Those decisions need additional measurements and qualified design guidance beyond a fixed unit conversion.
Frequently Asked Questions
How many joules are in one BTU?
One international-table British thermal unit equals approximately 1,055.06 joules.
Is BTU a unit of power?
BTU is energy. BTU per hour is a rate of power and is a different quantity.
Can this size a heater or air conditioner?
No. It converts stated energy values and does not calculate heating or cooling load, efficiency, climate, or equipment capacity.
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