Convert a volume of water or air and a temperature change into BTU, kilowatt-hours and therms.
How it works
Water takes 8.33 BTU per gallon per degree Fahrenheit, and air takes about 0.018 BTU per cubic foot per degree. Multiply by the volume and the temperature change.
Before you order
- Room heating and cooling sizing depends on heat loss, so use the heat loss or AC size calculators for that job.
- Real systems lose heat during warm-up, so plan on more than this minimum.
- Divide BTU by 3,412 to compare against electric heaters in kWh.
Common questions
What is a BTU?
The heat needed to warm one pound of water by one degree Fahrenheit.
How do I convert BTU to tons?
One ton of cooling is 12,000 BTU per hour.