Skirting Board Calculator & Corners

What Goes Into the Numbers

The calculator starts with the full perimeter of your room — twice the length plus twice the width. From that total, it subtracts the width of each doorway opening, because skirting stops where the door architrave begins. The result is your net skirting length.

A waste factor is then applied to the net length to account for material lost to cutting. Every internal corner needs a cope or mitre cut, and every external corner needs a mitre. These cuts produce short offcuts that are often too small to reuse. The default 10% waste covers a standard rectangular room with four internal corners and one or two doorways.

The final step divides the total length (net length plus waste) by the individual board length you have chosen, then rounds up to a whole number. Standard UK skirting boards come in 2.4m or 3m lengths. Longer boards mean fewer joints along a wall, but they are harder to transport and handle in tight spaces. If you are planning to paint the skirting after fitting, our paint coverage guide explains how to estimate the quantity for trim work.

Making Sense of the Output

Three outputs appear after you press Calculate. Room perimeter is the full circuit of the room before any deductions — this is useful as a sanity check against your tape measure reading. Net skirting length is the perimeter minus all doorway widths, representing the actual length of wall that needs skirting.

Boards needed is the number of whole boards to buy. This figure includes your waste allowance and is always rounded up, because you cannot buy a fraction of a board. In practice, offcuts from one wall often fit a shorter run on another wall, which is why 10% waste is usually sufficient for a simple room. The rounding-up itself also creates a small buffer — if the maths says 6.3 boards, you buy 7, and that extra 0.7 of a board covers most minor miscalculations. The perimeter-based approach is similar to how hedge spacing works outdoors — both divide a linear measurement into fixed-length units.

Common Mistakes to Avoid

Corner joints are where skirting jobs succeed or fail. Internal corners (where two walls meet inward, like the corner of a bedroom) should always use a cope joint. A coped joint scribes one board to follow the profile of the other, creating an interlocking fit that stays tight even as the house settles and walls move fractionally. Cut the first board square into the corner, then cope the second board to sit over it.

External corners (outward-pointing corners like a chimney breast or pillar) use mitre joints. Cut both boards at exactly 45 degrees with a mitre saw. Test-fit the joint before applying any adhesive. If the corner is not perfectly square (and many are not), you may need to adjust the angle by a degree or two.

Fix skirting boards with a combination of panel adhesive and panel pins. The adhesive carries the weight and bonds the board to the wall, while the panel pins hold the board in position while the adhesive sets. Nail the pins at a slight downward angle so they bite into the plaster behind.

Start with the longest wall in the room and work your way around. This approach lets you use the longest boards on the most visible runs, saving shorter offcuts for behind furniture or inside alcoves. At each doorway, cut the skirting square so it sits flush against the architrave. The two profiles, skirting and architrave, should meet cleanly without overlapping.

Profile choice is partly aesthetic and partly practical. Ogee skirting has a traditional S-curved profile common in Victorian and Edwardian homes. Torus has a simpler rounded half-circle. Bullnose is a plain rounded top edge. Pencil round and chamfered profiles suit modern interiors with clean lines. Ornate profiles like ogee require more skill to cope cleanly because the curves must match precisely at the joint. Coordinating skirting with wallpaper above creates a cohesive room finish, so choose a profile height that works with your paper's pattern scale.

When to Adjust These Numbers

Rooms with more than four corners need extra waste allowance. Alcoves, chimney breasts, and bay windows all create additional corners that require mitre or cope cuts. Add roughly 2% waste per extra corner beyond the standard four.

Bay windows with angled walls need custom mitre angles rather than the standard 45 degrees. Measure the actual angle of each bay panel with a sliding bevel gauge and transfer that angle to your mitre saw. A five-sided bay typically has 135-degree wall junctions, requiring 22.5-degree mitres.

Hallways with many doors have a high deduction ratio. A hallway with five door openings may only need skirting on 60% of its perimeter. In these cases, check that the calculator's board count still makes sense — you may be able to drop down to shorter boards to reduce waste from long offcuts.

If you are fitting skirting over a floating floor (laminate, vinyl, or engineered wood), leave a 2mm gap beneath the skirting board. Floating floors expand and contract with temperature and humidity, and the skirting must not pin the floor down. The gap is invisible once fitted but prevents buckling. Our laminate flooring estimator accounts for expansion gaps when calculating board quantities.