TradeCalculator.co.uk
Radiator Paint Calculator — How Much Radiator Paint Do I Need?
Calculate specialist radiator paint for all radiator types. Accounts for fins, columns and hidden surfaces.
Number of radiators in the system
Common heights: 300, 450, 600, 700mm
Width across the front
2 coats recommended
Adds 15% for drips and complex surfaces
15% recommended for radiator work
Metal primer for bare or previously-painted radiators
How We Calculate This
Our radiator paint calculator accounts for the hidden surfaces that make radiators use far more paint than their flat dimensions suggest. Different radiator types have vastly different total surface areas.
The formula
Surface area = Front area × Surface multiplier × Coats
Paint needed = Surface area × Wastage factor ÷ Coverage rate
Surface area multipliers (our estimates)
Radiator manufacturers publish heat output, not paintable surface area, so the figures below are TradeCalculator rules of thumb that account for fins, convector panels and column faces — treat them as a guide and check your own radiator if it is unusual.
- Single panel (Type 11): approximately 1.5× flat front area
- Double panel (Type 22): approximately 2.5× flat front area
- 2-column radiator: approximately 3.0× flat front area
- 3-column radiator: approximately 4.0× flat front area
- 4-column radiator: approximately 5.0× flat front area
- Towel rail: approximately 2.0× flat front area
We recommend 15% wastage for radiator painting as the complex surfaces and vertical application result in more paint loss than flat wall painting.
Frequently Asked Questions
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Last updated: February 2026
Verified against UK standards · estimates only, confirm with your supplier.