Brown: the step-up from red
Brown is the plug you reach for when red isn’t enough — the same idea a size bigger. The masonry bit for a brown rawlplug is 7 mm, every time, paired with a screw around 4.0–6.0 mm (a No.10 is the usual partner). In solid brick a brown plug holds roughly 25 kg per fixing. It’s the everyday heavy plug: kitchen wall units, loaded bookshelves, and curtain poles carrying thick, lined curtains.
Red or brown — when to step up
This is the real brown-plug question, and the honest answer is to work it out per fixing, not per fixture: divide the item’s weight by the number of plugs holding it, then leave margin — the trade rule is to size each plug for about 1.5× the load it will actually carry.
- Weight per fixing. Red holds ~20 kg per plug in solid brick, brown ~25 kg. A 24 kg shelf on four plugs is 6 kg each — red is plenty. Loaded to 60 kg it’s 15 kg each — still red’s range, but brown buys margin. A heavy wall unit on two plugs can be 20 kg+ each — that’s brown, or bigger.
- Screw size. If the fixture’s own holes take a fat No.10 screw, you want brown — red’s 6 mm hole suits a slimmer No.8.
- Substrate. In soft, old or aerated block everything holds less, so sizing up to brown (or a steel anchor) buys back some margin.
When you’re on the fence, size up — a brown plug in a 7 mm hole costs nothing extra and fails later than a red one worked to its limit. And above roughly 50 kg per fixing, stop reaching for plastic altogether: that’s a sleeve anchor job. If red is all you need, the red wall plug page has its sizes.
The one rule that stops most failures
The drill bit matches the plug; the screw is 1–2 mm smaller than the bit. A red plug wants a 6 mm hole, a brown plug a 7 mm hole, and the screw bites the plug and expands it against the wall. Get it backwards — an oversized hole, or a screw too fat — and the plug spins or splits before it grips. Colour-to-size is a common UK convention, not a guaranteed standard, so it still varies a little by brand: check the packaging, which prints the bit and screw sizes.
Fitting it so it holds
- Use the exact bit size — don’t oversize. The number-one failure is a hole that’s too big, so the plug spins. If it’s already too big, go up a plug size, or fill and re-drill.
- Depth beats width. In brick with voids go longer, not wider — width invites splitting, length adds grip.
- Drill slightly deeper than the plug and clear the dust before inserting it — packed dust stops the plug seating and causes pull-out.
- Drill the brick, not the mortar joint, and get past the plaster into the brick or block behind — a plug gripping only the plaster skim pulls straight out.
- Use a hammer drill and a carbide masonry bit — brick and block need percussion. Not sure which bit? See the masonry drill bit guide, and the size converter for mm ↔ imperial.
When a wall plug is the wrong fixing
Never in plasterboard. A wall plug needs solid material to expand against; in hollow plasterboard it just spins and tears out. On a stud wall or ceiling, use a drywall anchor instead — a different fixing for a different wall.
Above roughly 50 kg per fixing, step up from plastic. Past that, a plastic plug is the wrong tool — move to a steel sleeve anchor or another concrete anchor sized for the load. It’s about picking the right fixing, not fine print.
Common questions
What size drill bit for a brown rawlplug?
7 mm — every time. Brown plugs (rawlplugs) are unanimous across UK sources: drill a 7 mm hole with a carbide masonry bit in a hammer drill. Pair it with a screw around 4.0–6.0 mm (a No.10 is typical), remembering the screw is 1–2 mm smaller than the bit. A brown plug holds roughly 25 kg per fixing in solid brick as an indicative maximum — check the packaging, since sizing varies slightly by brand.
What screw fits a brown wall plug?
A screw around 4.0–6.0 mm in diameter — a No.10 is the usual partner, though a No.8 works at the lighter end. As with every plug, the screw is 1–2 mm smaller than the 7 mm drill bit so it expands the plug against the wall without splitting it. Make sure the screw is long enough to pass through your fixture and engage the full length of the plug in the brick behind any plaster.
When should I use brown instead of red?
Step up to brown when the load per fixing is heavier, when the fixture takes a fatter No.10 screw, or when the wall is soft, old or hollow block. Work it out per fixing, not per fixture: divide the weight by the number of plugs and add margin (aim for about 1.5× the per-plug load). Red holds ~20 kg per fixing, brown ~25 kg — so for kitchen wall units, loaded shelving and heavy curtain poles, brown; for brackets, rails and mirrors, red is fine. When you're on the fence, size up. Above ~50 kg per fixing, use a sleeve anchor instead.
Are brown plugs strong enough for a kitchen unit?
For a typical wall cabinet, yes — provided it's fixed into solid brick or block with enough plugs and the load is shared. A brown plug holds around 25 kg per fixing in solid brick (indicative), and a wall unit normally hangs on several fixings top and bottom, so the per-plug load stays well within range. What matters: drill into the brick, not the mortar or a plaster skim; use every fixing point the unit provides; and check the wall is solid — on plasterboard or a hollow wall you'd need a different fixing. For a very heavy or tall unit, or a stone/tile substrate, follow the cabinet maker's fixing spec or step up to a steel anchor.
How much weight will a brown wall plug hold?
Around 25 kg per fixing in solid brick — treat it as an indicative maximum, not a rated spec. Actual hold depends on the substrate (weaker, older or aerated block holds much less), screw engagement and installation. And it's PER FIXING POINT: most fixtures use two or more plugs, so divide the total weight between them and add margin (size each plug for roughly 1.5× the load it carries). Use at least two fixings over about 10 kg, and above ~50 kg per fixing move to a steel sleeve anchor.
Where these numbers come from
The brown-plug sizing here — a 7 mm bit, a 4.0–6.0 mm screw, and an indicative ~25 kg per fixing in solid brick — is cross-referenced across UK fixing suppliers and manufacturer references (Rawlplug, Screwfix, Toolstation and UK trade guides), which are unanimous on brown = 7 mm. The red-vs-brown, per-fixing and 1.5×-margin guidance follows the same sources’ load advice. Figures are indicative maxima in solid brick, not rated specifications, and colour sizing is a common convention rather than a formal standard — the packaging is the final word. For structural or safety-critical fixings, follow the manufacturer’s data and step up to an engineered anchor.
Wall-plug sizing here is common-convention UK guidance for light-to-medium DIY fixings. Colour coding and load figures vary by brand — always follow the plug packaging. Loads are indicative maxima in solid brick, not rated specifications; for structural, heavy or safety-critical fixings, step up to an engineered anchor and follow the manufacturer's data.