How the skirting calculator works
The calculator adds up the wall lengths (the room perimeter), takes off door openings and anything else the skirting won't run along, and adds an allowance for mitres and offcuts. It then rounds up to whole lengths of the size you're buying. Architrave is counted in door sets: two legs and one head, about 5.1m per side of a standard door.
Fitting tips
- Buy lengths longer than your longest wall where you can. Joins on a long run are hard to hide.
- Mitre external corners at 45°. Scribe internal corners with a coping saw so they stay tight if the wall isn't square.
- Fit architrave before skirting, so the skirting butts neatly against the architrave plinth.
- Prime MDF cut ends and caulk the top edge before the final coat of paint.
- Leave a few millimetres above hard floors, or fit after the flooring so the skirting covers the expansion gap.
Worked example: a 4m × 3.5m bedroom
The walls add up to 2 × (4 + 3.5) = 15m. Take off about 0.85m for the door and that leaves 14.15m of skirting. With 10% for mitres it's 15.6m, so 4 lengths of 4.2m MDF. Here that works out neatly: every wall is shorter than 4.2m, so each wall gets one piece with no joins. Architrave for both sides of the door is 2 sets, about 10m. You'll also want around 4 tubes of grab adhesive and 3 of decorator's caulk.
Before buying, check each wall against the length you're buying. Where a wall is longer, you'll need a joint, so either choose 5.4m lengths or plan for a neat 45° scarf joint away from the doorway.
Choosing skirting
- MDF: straight, knot-free, comes primed and is sold in long 4.2–4.4m lengths. It's the usual choice for painted skirting. Use moisture-resistant MDF in bathrooms and kitchens.
- Pine or softwood: tougher on the edges and can be stained or varnished, but may have knots and slight bows.
- Height and profile: about 119–145mm suits most modern rooms, and 168mm or taller suits period rooms with high ceilings. Match existing profiles (torus, ogee, chamfered, square) when you're only replacing part of a house.
Cutting and fixing
A mitre saw makes clean 45° cuts for external corners. Internal corners stay tight on out-of-square walls if you scribe them: cut one board square into the corner, then shape the end of the other with a coping saw to fit its profile. Fix with grab adhesive along the back and a few screws or nails into studs or plugs. Fill the holes, caulk the top edge and any joints, then paint.
Common mistakes
- Ordering exact metres. You buy whole lengths and lose a little at every mitre. Plan the pieces wall by wall, not just by the total.
- Fitting before the flooring. With laminate or LVT, fit the skirting afterwards so it covers the 8–10mm expansion gap and you don't need beading.
- Skipping the primer on cut ends. Raw MDF ends soak up paint and swell if they get damp.
Laying a new floor first? The flooring calculator covers packs and underlay, and the paint calculator covers the walls. More indoor jobs are in floors, walls and decorating.