Best starting point
Use the heater room size calculator if the room feels cold or expensive to heat. Use the dehumidifier and radiator pages when you already know the appliance type and want a more specific size guide.
Sizing hub
Check whether the room or appliance is the wrong size before chasing the wrong fix
Sizing mistakes make costs look worse, comfort look worse, and appliances look weaker than they really are. Use this section when the issue might be room fit rather than tariff, brand or headline efficiency claims.
Heater room size calculator
Best general route for checking how much heat a room is likely to need.
Dehumidifier size by room
Best when drying clothes or damp-control performance feels weak.
Radiator size by room
Useful for central-heating rooms where output looks too low for the space.
Browse by problem
- The room never feels warm enoughCheck heater wattage by room and then compare heater types if needed.
- The room stays damp or clothes dry too slowlyCheck whether the dehumidifier is undersized for the room and moisture load.
- The cost feels too high for a small roomCheck heater size first, then use the running-cost calculator.
- I am choosing between heater typesOnce size is clear, compare the options properly.
What to do after a sizing check
- If the unit is too small, fix that first before over-analysing tariff or brand.
- If the size looks right, move into running cost or comparison pages next.
- For damp or drying problems, room moisture load can matter as much as floor area.
What sizing pages should lead into next
These routes help the user move from “what size?” into “what will it cost?” or “which option should I buy?”
If the room feels cold
If the room feels damp or clothes take too long to dry
If fixed heating is part of the decision
Sizing FAQ
These are the points most likely to stop a sizing result being misread.
Why does a room-size estimate still need judgement?
Because room volume is only the starting point. Insulation, exposure, glazing, ceiling height and how warm you want the room all affect the practical answer.
Can a high running cost be a sizing problem rather than a tariff problem?
Yes. An undersized heater or dehumidifier often runs harder for longer, which can make the bill look like a tariff problem when the real issue is that the appliance is mismatched to the room.