How Many Radiators Per Room?
Quick Answer
Typically 1 radiator for small rooms, 2 for large living areas
Based on heat loss calculation: ~100 watts/m² for a well-insulated room, ~150 watts/m² for older properties
Quick Sizing Guide
As a rough rule of thumb for UK homes:
- Small bedroom (8–10m²): 1 radiator, ~1,000–1,500W BTU output
- Double bedroom (12–15m²): 1 radiator, ~1,500–2,000W
- Living room (18–25m²): 1–2 radiators, ~2,500–3,500W total
- Open-plan kitchen/diner (25–35m²): 2–3 radiators, ~3,500–5,000W total
- Bathroom (4–6m²): 1 towel radiator, ~600–1,000W
Factors That Increase Heat Demand
- External walls (especially uninsulated solid walls)
- Large or single-glazed windows
- High ceilings (above 2.4m)
- North-facing rooms
- Rooms above unheated spaces (garages, cellars)
Placement Tips
- Position under windows to counteract cold draughts
- Leave at least 50mm clearance from the floor and 40mm from the wall
- Do not place behind furniture — this blocks heat output
- Two smaller radiators on opposite walls give better heat distribution than one large one
Last updated: April 2026