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Yellow, red and brown wall plug size

Updated: October 2026

You are holding a yellow plug, a red plug and a brown plug, and three websites have already named three drill bits. Yellow, red and brown wall plug size is a trade habit, not a British Standard. The drill and the screw on the packet in your hand are the size. This page shows where the charts clash, and which packs in the [wall plug comparison](/hub/sockets-and-extension-leads/wall-plug) are not in that colour system. Rawlplug's UNO sheet, CMT, Toolstation and DIY Doctor were compared on 16 October 2026. Nothing here was pull-tested. A qualifying purchase can earn a commission at no extra cost to you.

You are holding a yellow plug, a red plug and a brown plug, and three websites have already named three drill bits. Yellow, red and brown wall plug size is a trade habit, not a British Standard.

Our top picks

PlasPlugs PlasPlugs 52 assorted wall plugs

Best overall

PlasPlugs PlasPlugs 52 assorted wall plugs
7.7/10about £4.22
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Merriway Merriway BH07204 yellow, red and brown

Rank 2

Merriway Merriway BH07204 yellow, red and brown
8.4/10about £4.56
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Yibaijia Yibaijia 110-piece M6 and M8 set

Alternative

Yibaijia Yibaijia 110-piece M6 and M8 set
7.6/10about £4.99
View offer
On this page
  1. 1.What the colours usually mean
  2. 2.Where the charts clash
  3. 3.Screw diameter, not the colour name
  4. 4.Packs that are not a colour chart

What the colours usually mean

In UK DIY, yellow is the small plug, red the middle, brown the larger of the three. Toolstation's general guide puts yellow at 5 mm, red at 6 mm and brown at 7 mm, and blue at 8–10 mm. That habit opens the right compartment. It is not a size you can drill from if your packet disagrees. Rawlplug's UNO sheet is one maker's table. Yellow is 5 × 24 mm, screws 3.0–4.5 mm, hole depth 34 mm. Red is 6 × 28 mm, screws 3.5–5.0 mm, depth 38 mm. Brown is 7 × 30 mm, screws 4.0–6.0 mm. Blue is 8 × 32 mm. Grey is 10 × 36 mm. If your plug is not a UNO, you do not inherit the table by being red. CMT prints a different red: 5.5 × 34 mm with a 5.5 mm bit, against yellow 5 × 22 mm and brown 7 × 40 mm. CMT says the colours are a trade convention, not a standard. Brown is larger than red. It is not a heavy-duty rating.

Where the charts clash

Rawlplug's blue UNO is 8 × 32 mm. DIY Doctor's colour bands put blue at a 10 mm drill. Grey, on the UNO sheet, is the 10 mm plug. Drill 10 mm for an 8 mm plug and the sleeve rattles. Merriway is a third list, and the only one of these five that prints yellow, red and brown as gauges: yellow 4 to 6, red 6 to 10, brown 10 to 14, with no millimetres. A No. 8 can sit inside Merriway's red band and outside a UNO red band of 3.5–5.0 mm. Timco's loads in named concrete are Timco's test. They are not a rating for these five packs. BS EN 14566 does not define these colours. When you do have a number, depth and dust are the fitting sequence.
PlasPlugs PlasPlugs 52 assorted wall plugs

Testsieger

PlasPlugs PlasPlugs 52 assorted wall plugs
7.7/10about £4.22
View offer

Screw diameter, not the colour name

Too thin a screw, and the sleeve stays slack. As wide as the outside of the plug, and the plastic splits. On a red UNO the band is 3.5–5.0 mm. Merriway's red is gauges 6 to 10. A No. 8 screw fits a red plug whose packet includes a No. 8. It does not fit a red plug whose packet stops at 5 mm. Yibaijia's plugs are yellow, and the yellow is the plastic, not the small gauge. The sizes are M6×30 mm, M6×40 mm and M8×40 mm. Treating that yellow as a 5 mm plug would pair an M8 screw with the wrong hole. None of these five listings prints a kilogram against a colour. A load needs a maker table for that anchor, such as an ETA on stated Fischer DuoPower sizes.

Packs that are not a colour chart

Only Merriway BH07204 prints those gauge bands, forty of each colour, plugs only, at about £4.56. Use the bands for those plugs. Do not paste them onto the other four. PlasPlugs is grey nylon, 52 plugs at about £4.22. One buyer measured 5 mm, 6.5 mm, 8 mm and 10 mm and missed 6 mm and 7 mm. Those millimetres are a review, not the specification table. Lemiyoo is greyish blue, sized M5×25, M6×30, M8×40 and M10×50, four of them at the largest. Sort by the number. DODIYDO states 2.5 cm to 8 cm, and the listing says ten sizes while reviews describe about five. There is no yellow-red-brown key. When the packet has numbers, those numbers win. When it has none, do not drill a structural hole from a blog.

Common questions

What drill bit is a red plug?
It depends which red plug. Rawlplug's red UNO is 6 mm. CMT's red is 5.5 mm with a 5.5 mm bit. Toolstation's general guide says 6 mm and flags maker variation. Merriway's red is gauges 6 to 10, with no millimetre bit on the listing. Drill the size on your packet.
What screw fits a yellow plug?
On Rawlplug UNO, yellow takes 3.0–4.5 mm. On Merriway's listing, yellow is gauges 4 to 6. On Yibaijia, yellow is the colour of an M6 or M8 plug, so the screw is the one packed with that length. A yellow plug from another maker does not inherit either list.
Is brown the heavy-duty plug?
Brown is usually the larger colour, around 7 mm on Toolstation's general guide, 7 × 30 mm on UNO, or 7 × 40 mm at CMT. Larger is not a kilogram rating. Timco's higher figure for its own brown plug is Timco's test in named concrete. It does not transfer to an unrated assortment.
Is blue 8 mm or 10 mm?
On Rawlplug's UNO sheet, blue is 8 × 32 mm and grey is 10 × 36 mm. Other DIY pages put blue at 10 mm, or at 8–10 mm as a range. That range is already two plugs. Drill 8 mm only when your plug says 8 mm.
Can I use a No. 8 screw in any red plug?
No. You can use a No. 8 where the packet's red range includes it. Merriway's red band is gauges 6 to 10, so a No. 8 sits inside that claim. A red UNO states 3.5–5.0 mm, which is a different limit. A thick screw in a narrow plug splits the plastic. A thin screw in a wide plug never expands it.

Related pages

Wall plug buying guide

Best wall plugs

Wall plug

How to fit wall plugs in solid brick, block or concrete

Wall plugs: plasterboard or brick, and which fixing

Sources

Public UK sources on masonry plugs, plasterboard fixings, and drilling near cables. Listings checked 16 October 2026. Prices on amazon.co.uk move.

  1. DIY Doctor, fixing to masonry (retrieved 16 October 2026)
  2. DIY Doctor, fixing to plasterboard (retrieved 16 October 2026)
  3. Rawlplug UNO data sheet (retrieved 16 October 2026)
  4. Fischer DuoPower ETA (retrieved 16 October 2026)
  5. EOTA EAD 330284-00-0604 (retrieved 16 October 2026)
  6. HSE, work near electricity (retrieved 16 October 2026)
  7. HSE CIS65 (retrieved 16 October 2026)
  8. BSI, BS EN 14566 (retrieved 16 October 2026)