Find the correct wall plug (rawl plug/anchor) size for your screw, wall material, and load. Includes drill bit size and pull-out strength estimates.
Choosing the right wall plug (also called a rawl plug or wall anchor) is essential for secure fixings. A plug that's too small won't grip; one that's too large won't expand properly. The correct size depends on the screw gauge, wall material, hole depth, and the load you plan to hang. Matching the drill size matters just as much as matching the screw.
This calculator matches your screw size to the correct plug color code (following the standard UK/EU color system), recommends the drill bit diameter, minimum hole depth, and estimates pull-out strength for different wall materials. It covers everything from lightweight picture frames on plasterboard to heavy shelving in solid brick or concrete.
Whether you're a DIY homeowner or a professional installer, this tool eliminates guesswork and ensures your fixings are safe and code-compliant. The reference table below covers all common plug sizes from 4 mm yellow to 14 mm brown, with load ratings for each wall type.
Use this calculator to match screw size, wall material, and anchor diameter before drilling. It is helpful when you need a quick check on drill bit size, embedment depth, and whether a basic nylon plug is enough for the load you plan to hang. That reduces the risk of drilling once and discovering the fixing is wrong for the wall.
Plug diameter ≈ screw gauge × 2 (mm approximate). Drill bit = plug outer diameter. Minimum depth = plug length + 10 mm. Safe load = pull-out strength / safety factor.
Result: Red plug (6 mm), 6 mm drill bit, 45 mm hole depth, safe load 40 kg
A No. 8 screw in brick uses a red 6 mm plug with ample capacity for 15 kg at 3× safety factor.
The standardized color system makes it easy to identify plug sizes at a glance. Yellow plugs (5 mm) suit No. 4-6 screws for light loads. Red plugs (6 mm) are the most common, fitting No. 6-10 screws for medium loads. Brown plugs (7 mm) handle No. 10-14 screws for heavier fixings. Blue and grey plugs (10-14 mm) are for heavy-duty applications with coach screws and bolts.
Solid brick and dense concrete provide the best pull-out strength, typically 150-300 kg per plug depending on size. Hollow brick and lightweight block offer 50-70% of solid masonry strength. Plasterboard has very limited plug holding power (10-30 kg per fixing), so toggle anchors or metal self-drill anchors should be used instead for anything beyond light picture frames.
Building regulations and manufacturer guidelines specify minimum embedment depths, edge distances, and spacing between fixings. For safety-critical fixings like handrail brackets, TV wall mounts, or overhead items, always use the manufacturer's specified plug and screw combination with appropriate safety factors. When in doubt, use a larger plug size and longer screw — over-specifying fixings is always safer than under-specifying.
Colors follow a standard system: yellow (5 mm), red (6 mm), brown (7 mm), blue (10 mm), grey (10-12 mm). Each color fits a range of screw gauges.
Standard plugs work poorly in plasterboard. Use spring toggles, self-drill anchors, or gravity toggles for plasterboard fixings above 5 kg.
A minimum 3× safety factor is standard for general fixings. Use 5× for overhead loads and 4× for items with dynamic forces (e.g., TV mounts).
Drill at least the full plug length plus 10 mm to allow dust clearance. The plug should sit flush with or slightly below the wall surface.
Yes — the screw should extend at least 5-10 mm beyond the plug tip to fully expand it. A screw that's too short won't engage the plug properly.
Always round up to the next plug size. A slightly larger plug provides more grip and a higher load rating.