HEATING GUIDES / RADIATOR SIZING
BTU calculator
Find the heat output your room needs. Enter a few details to get an estimate in BTU/hr and watts, then compare radiators or heated towel rails for your space.
SIZING ADVICE
Frequently asked questions
What does BTU/hr mean?
BTU stands for British Thermal Unit. BTU per hour and watts both describe how much heat a radiator can deliver over time.
Can a heated towel rail heat my bathroom?
Compare its rated output with your room’s heat requirement. If it falls short, you may need a higher-output rail or a separate radiator.
What does ΔT50 mean on a radiator listing?
It is the condition used to rate the radiator when the average water temperature is 50°C above room temperature. If your system runs cooler, ask for the radiator’s output at your operating temperature.
Can I use more than one radiator?
Yes. Compare the combined output of the radiators at your system’s operating temperatures with the total heat requirement for the room.