Surveying & site
Room Volume Calculator
Heating, extract fans and dehumidifiers are all sized from one number: how much air the room holds.
Calculator
Fill in the fields above to see results.
How it works
Volume is length x width x ceiling height. The result is shown in m3, cubic feet and litres; pair it with the radiator BTU or ventilation calculators to size equipment.
Frequently asked questions
What ceiling height should I use?
Measure floor to ceiling in the main space - UK rooms are typically 2.3-2.4 m. For sloped ceilings, use the average height across the floor area.
Why do heating engineers ask for room volume?
Heat demand scales with the air you warm: a 2.4 m ceiling room and a 3.5 m Victorian one with the same floor area need very different radiators.