Building & renovation
How many spray cans for radiators?
How many 400 ml spray cans to repaint radiators — from total m², coats and coverage per can.
Quick answer
Radiator enamel in aerosol covers far less wall area than you expect — fins, valves and overspray mean ~1–2 m² per 400 ml can per coat. Default 1.5 m²/can, 2 coats, 10% waste. Example: double panel radiator 2.5 m² → 2.5 × 2 ÷ 1.5 × 1.1 ≈ 3.7 → 4 cans.
Advanced settings
Spray cans needed
4 × 400 ml
Radiator enamel sprays cover less area than wall paint — fins, valves and overspray eat product. A 400 ml can often does 1–2 m² per coat on a typical panel radiator. Ventilate well; heat the room only after full cure per label.
How it works
Measure the actual metal surface (both sides if you paint behind), not the wall footprint. Heat-resistant formulas need full cure before switching heating back on — check the can label.
Turn the heating off and let radiators cool completely — painting warm metal traps solvent and yellows within weeks. Wire-brush loose rust with a wire brush for rust before spraying; a radiator roller between fins catches what aerosol overshoots. Order radiator spray paint rated to at least 80–90 °C surface temperature.
Two things to take off before the first can, not after. The thermostatic head has to come off or be masked: enamel on it insulates the sensor, and from then on the valve reads a temperature that is not the room's and the radiator either never opens or never closes. And hang a sheet on the wall behind — aerosol overspray drifts far further than the fins, and it lands as a dry dust that shows up on a matt wall when the light rakes across it. Keep the coats thin, too: film thickness very slightly reduces output, unnoticeable at two coats and real by four.
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Frequently asked questions
How do I estimate radiator m²?+
Count flat panels and columns you will coat — a typical double convector 100×60 cm is roughly 2–3 m² including edges. Add all radiators in the room for a batch repaint.
One or two coats?+
Bare metal or colour change: two coats standard. Refresh over sound same-colour enamel: one coat may suffice — set coats to 1 in advanced.
Do I need to sand radiators first?+
Remove loose rust and gloss on failing paint — keying the surface improves adhesion more than buying extra cans. This tool sizes paint quantity only, not prep materials. A clean, keyed surface often lets you drop from two coats to one on maintenance jobs.
Spray vs brush for radiators?+
Spray reaches between fins faster; brush + radiator roller avoids overspray on walls but uses similar litres. Coverage per can in this calculator assumes aerosol application.
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