BTU Calculator

Find the ideal radiator size for any room with this BTU calculator. It quickly provides a heat output estimate, keeping your space warm and energy-efficient. Avoid radiators that are too weak or wasteful. Enter your room details, and get the required heat output in BTUs and watts instantly:

Room Length (m): Room Width (m): Room Height (m): Total Window/External Door Area (m²):

Insulation Level: Number of Outside Walls: What is above the room? What is below the room?

FAQs

What is a BTU?

A BTU (British Thermal Unit) is a unit of heat energy. It measures the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. In heating, BTUs indicate how much heat a radiator needs to effectively warm a room.

Why do I need to calculate BTU before choosing a radiator?

If your radiator’s BTU output is too low, the room won’t heat up properly. If it’s too high, you may waste energy and money. A proper BTU calculation ensures you choose the right radiator size for efficient heating.

Can I use multiple radiators instead of one large one?

Yes! If one radiator can’t provide enough BTU, you can install multiple radiators to distribute heat more evenly. Just ensure their combined BTU matches the required total.