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Radiator spray paint coverage and how many cans

Updated: 22 October 2026

You priced one 400 ml aerosol for three doubles and reached the last panel with the can rattling empty and the fins still grey at the back. Radiator spray paint coverage is where that surprise starts. Some brands quote square metres per litre, others per can, and none of them subtracts overspray on the skirting. This page turns the six amazon.co.uk fields into shopping arithmetic from the stated figures, not a lab test. Which can to open stays on the [radiator spray paint comparison](/hub/heating/radiator-spray-paint). Peter F. checked those listings and public UK sources. There was no measured spray trial. A qualifying purchase can earn a commission at no extra cost to you.

You priced one 400 ml aerosol for three doubles and reached the last panel with the can rattling empty and the fins still grey at the back. Radiator spray paint coverage is where that surprise starts.

Our top picks

PlastiKote PlastiKote Trade Gloss 400 ml

Best overall

PlastiKote PlastiKote Trade Gloss 400 ml
8.0/10about £8.49
View offer
Hammerite Hammerite Satin 400 ml

Rank 2

Hammerite Hammerite Satin 400 ml
8.1/10about £9.23
View offer
Rust-Oleum Rust-Oleum Gloss 400 ml

Best value

Rust-Oleum Rust-Oleum Gloss 400 ml
7.6/10about £10.56
View offer
On this page
  1. 1.Per can or per litre
  2. 2.What each can in this set actually states
  3. 3.A medium panel, two coats, and the spare
  4. 4.When the tin will not stretch

Per can or per litre

Mixing units is the trap. A per-litre rate assumes 400 ml, 0.4 litre, at the maker's film thickness. A per-can rate is easier to shop with and often smaller. Homebuilding's around two square metres, and one Hammerite can for one radiator, sits closer to shaped steel than scaling 10–12 m² per litre to 4–5 m² and calling that fins, backs, and two coats. Hammerite states 10–12 m² per litre. Rust-Oleum states about 2 m² per 400 ml can. Twist & Spray states 4–4.8 m² per litre. Magnolia gloss states about 1.5 m² per can. Trade gloss states about 1.25–1.75 m² per can. Satin chrome had no coverage field on the October 2026 listing. Do not invent a number from another row.

What each can in this set actually states

Hammerite at 10–12 m² per litre times 0.4 litre is roughly 4.0–4.8 m² on paper, not a finned double with two coats and masking losses. A quote of about 2 m² can describe that job. The listing says about 2 m² per 400 ml. A Tor Coatings sheet cites approximately 2.5 m² per can. Do not average those two figures. Twist & Spray at 4–4.8 m² per litre scales to about 1.6–1.9 m² per can before fins and a second coat. Magnolia at 1.5 m² and trade gloss at 1.25–1.75 m² per can are modest, so a large column painted on the back needs two tins. Chrome has no figure here. Picks, once you know the count, are on best radiator spray paint.
PlastiKote PlastiKote Trade Gloss 400 ml

Testsieger

PlastiKote PlastiKote Trade Gloss 400 ml
8.0/10about £8.49
View offer

A medium panel, two coats, and the spare

A rule of thumb: one 400 ml can often covers one medium radiator in two light coats on sound paint. Buy a spare for a double, a column, heavy rust, or a colour change. Medium means a bedroom double, not a hallway of columns. The back and dense fins make the job larger than the front face. Rust-Oleum's about 2 m² per can is used up, on paper, by two coats over about 2 m². Fins, bare metal, and mist on the masking justify a second can. Magnolia at 1.5 m² approaches two tins once the back is included. A spare also covers a blocked nozzle, reported on magnolia gloss. Light coats are on how to spray paint a radiator.

When the tin will not stretch

Columns and fins have more surface than a flat panel of the same width. Bare metal drinks more paint than keyed yellow enamel. White over magnolia, or gloss over chips, often needs an extra coat for hide. One Rust-Oleum review describes a whole can in four mist coats on a large panel sanded to metal. That is one job, not a standard. Satin chrome has no coverage field here. Buy two and return one unopened if the retailer allows it, or read the tin. Do not apply Hammerite's per-litre rate to chrome. Trade gloss, below 2 m² per can, can cost more per square metre even though about £8.49 is the lowest shelf price in the set.

Common questions

How many square metres does a 400 ml can actually cover?
Only the tin you buy answers precisely. Trade gloss states about 1.25–1.75 m² per can, magnolia about 1.5 m², Rust-Oleum about 2 m². Hammerite's 10–12 m² per litre scales to roughly 4–4.8 m² on 400 ml, which is paper arithmetic, not a finned double with two coats.
Why does Hammerite say 10–12 m² per litre when articles say 2 m²?
The units differ. Per litre times 0.4 litre is not one shaped radiator with two coats. Articles often describe a practical job. Listings cite a spread rate. Homebuilding's around two square metres for Hammerite sits nearer shaped steel than the raw per-litre line. Keep the unit beside the number.
Do I count the back of the radiator?
Count it if you will see it or you want the colour even. The back adds area and awkward spraying, so the can empties sooner than a front-face estimate. Many refreshes paint the front only. If both sides matter, add at least one tin on a double or a column.
Should I buy a spare can before I start?
Yes, beyond one modest panel, and especially below about 2 m² per can or on fins and columns. A spare also covers a nozzle that blocks after the steel is keyed. One 400 ml can is a rule of thumb for one medium radiator in two light coats, not a promise for three doubles.
What do I do if the listing coverage is missing?
Do not guess from another brand. Satin chrome has no coverage field on the October 2026 listing. Read the tin, or order two and return the unopened can if the retailer allows it. Hammerite's per-litre rate does not belong on a chrome effect can.

Related pages

Radiator spray paint buying guide

Radiator spray paint

Best radiator spray paint UK: fins, gloss or colour

How to spray paint a radiator: prep, coats and cure

Radiator spray paint yellowing: satin versus gloss

Sources

Public UK sources named below. amazon.co.uk prices, stars and review counts on these six listings were taken from the listing files read for October 2026. Page updated October 2026.

  1. Crown Paints — How to paint a radiator (retrieved 21 October 2026)
  2. DIY Doctor — How to paint a radiator (retrieved 21 October 2026)
  3. GOV.UK — Aerosol Dispensers Regulations 2009 (retrieved 21 October 2026)
  4. HSE — SMART paint spraying INDG473 (retrieved 21 October 2026)
  5. Homebuilding — Best radiator paint (retrieved 21 October 2026)
  6. Expert Reviews — Best paint for radiators (retrieved 21 October 2026)