Skirting Board Calculator: Metres Needed Per Room
Calculates the metres of skirting board a room needs, deducting doorways and adding a waste allowance for corners. Optional cost estimate included.
For a room measuring 4.20 m by 3.80 m with one 0.90 m doorway, you need 16.61 m of skirting board. The room perimeter is 16.00 m, deducting the doorway leaves 15.10 m of wall, and a 10% waste allowance covers the mitred corners. Sold in 2.4 m lengths (about 8 ft), that means seven boards. If the room has internal corners, recesses or built-in wardrobes, raise the allowance to 15%. That lifts the figure to 17.37 m, which needs eight lengths.
Skirting board is sold in fixed lengths, so the metres you calculate must be converted into whole boards before you buy. Ordering a total in metres does not tell you whether the offcuts will cover each run of wall, because every wall section has to be cut from a board of the right length. The calculator follows the same order as a careful estimator: it takes the perimeter, deducts each doorway, applies your waste allowance and returns the linear metres to buy. Divide that figure by the board length to check how many lengths you need.
The method works best for rectangular rooms with straight walls and standard openings. Bay windows, alcoves, chimney breasts and sloping ceilings add cuts that a simple perimeter does not capture, so measure each wall separately in those rooms. Patio and sliding doors take a wider opening, which means a larger deduction. Older houses need extra care. In a Victorian terrace in Manchester or a stone cottage in the Cotswolds, walls are often out of square, so a larger allowance than the standard setting may be needed in practice.
Use the result as a planning figure rather than a final order. Measure each wall on site, note any doorways wider than expected and check the length of the boards you intend to buy. Keep a spare length for future repairs, because boards from different batches can vary slightly in colour.
The explanation below uses metric units; the calculator works in either system.
The result updates automatically.
A standard internal door opening is 0.80 to 0.90 m wide (about 2.6 to 3 ft).
Typical value: 10% for simple rooms; 15% for rooms with internal corners.
Baseboard length needed
from 15.10 m net, with 10% waste
- Total perimeter
- 16.00 m
- Door deduction
- −0.90 m
- Net length
- 15.10 m
How it works
Formula
How the calculation works
How to calculate skirting board for a room
Skirting board covers the joint between the floor and the wall, hides the gap left for floor expansion beneath laminate and engineered boards, and protects the base of the plaster from knocks and moisture. Working out the right length before you go to the shop saves a second trip and reduces the risk of ending up with boards from a different batch.
The calculation is simple, but it has three stages that are easy to skip: deducting openings, adding waste and converting the result into whole lengths. Each stage changes the number you buy, so it is worth working through them in order.
The formula step by step
The formula used in this calculator is M = (P − n × L) × (1 + D/100). The symbols are defined in the legend below the calculator, and each stage maps onto one part of the expression.
Step 1. Room perimeter. Add the four sides of the room, or use P = 2 × (length + width). In a room measuring 4.20 m by 3.80 m, the perimeter is 2 × (4.20 + 3.80) = 16.00 m. If a chimney breast or bay projects from the main wall, measure around it rather than across the room.
Step 2. Deduct doorways. Subtract the clear width of each opening, which is n × L in the expression. Measure the opening rather than relying on a standard size, because older doorways are often narrower or wider than modern ones. With one doorway of 0.90 m, the net length becomes 16.00 − 0.90 = 15.10 m. Patio doors and sliding doors take a wider opening, so the deduction can be large enough to change the number of lengths you need.
Step 3. Waste allowance. Multiply the net length by the waste factor, (1 + D/100). A 10% allowance gives 15.10 × 1.10 = 16.61 m. This allowance covers the offcuts from mitred corners and the short ends left at the end of each run. The calculator also offers a 15% setting for rooms with internal corners, recesses, alcoves or built-in wardrobes, which gives 15.10 × 1.15 = 17.37 m (rounded). These two percentages are planning settings built into this calculator, not figures taken from a published standard, so the right margin depends on the room. Where the walls are irregular, choosing the higher setting is the safer option.
Step 4. Convert to whole lengths. Skirting board is commonly sold in 2.4 m lengths, so the metre figure must be divided by the board length and rounded up. For 16.61 m, the division gives 16.61 ÷ 2.40 = 6.92, so seven lengths are needed, providing 16.80 m in total. For 17.37 m, the division gives 7.24, so eight lengths are needed. The calculator returns the linear metres. The conversion to lengths is a final check you make against the board length you actually buy.
Types of skirting board available in the UK
Four types cover most domestic work, and each one behaves differently when cut, fixed and painted.
MDF skirting is the most widely sold option in DIY stores and builders' merchants. It is made from fine wood fibres bonded with resin, gives a smooth surface for painting and costs less than solid timber. It does not cope well with prolonged moisture, and the edges swell if the board is soaked. It suits dry rooms such as living rooms and bedrooms, and most new work.
Solid softwood, usually pine, is common in older houses and is easy to cut, fix and repaint. Pine can be sanded and repainted many times, but it dents more easily than hardwood, and knots may need sealing before paint goes on so that resin does not bleed through.
Solid hardwood, such as oak, is harder wearing and suits period properties or rooms where a stained or clear finish is wanted. It costs more and is harder to cut cleanly, so a skilled fitter may be worth the cost for a large room.
PVC skirting is unaffected by damp, which makes it useful in bathrooms, kitchens and utility rooms. It can be cut with a fine-toothed saw or a knife and fixed with adhesive or clips. It looks less traditional, so it is usually chosen for practical rooms rather than formal living spaces.
Aluminium or metal profiles suit contemporary interiors and kitchens with resin or microcement floors. In domestic work they are more common in renovations of city flats than in new-build homes.
Board height and proportion
Board height changes how a room looks, so it should be chosen with the ceiling height in mind. In modern flats with ceilings around 2.4 m (about 8 ft), a narrower board keeps the walls in proportion, because a tall board divides the wall into bands and makes the ceiling appear lower. In older houses with ceilings of 2.7 m (about 9 ft) or more, taller boards are usually more in keeping with the room.
The most reliable check is to measure the existing skirting in a neighbouring room. In period properties, the original profile may be a feature worth keeping, and matching it avoids a visible change where rooms meet. The height of the board does not change the linear metres needed, so the calculation stays the same once the profile is chosen.
Common mistakes when buying skirting board
Forgetting the doorways. This is the most frequent error. Two 0.90 m doorways and a 1.40 m patio door take 3.20 m off the perimeter. Without that deduction, one or two lengths may be bought that are never needed.
Buying the exact amount. The net metres do not include the waste from mitred corners. The 10% setting suits a simple rectangular room, and a room with many corners or irregular walls is better served by the 15% setting.
Ordering in metres only. Stores sell skirting board in fixed lengths, so 16.61 m in theory is not the same as seven 2.4 m lengths in practice. The offcuts may not be long enough for the shorter runs, so convert to whole lengths before you go shopping.
Mixing batches. Colour and finish can vary slightly between production batches, particularly with painted MDF and PVC. Buy everything at once, check the batch number, and keep a spare length for future repairs.
When to use this calculator, and when not to
The formula works best for a rectangular room with straight walls, standard openings and no major features. It is a planning tool, so measure each wall on site before ordering. It is less suitable for:
- rooms with curved walls, bay windows or irregular outlines
- stairs and landings, where the board follows a sloped line
- rooms with many alcoves, chimney breasts or built-in units, where a wall-by-wall measurement is more accurate
Tools and fixings
A competent DIYer needs a mitre saw or mitre box, a fine-toothed saw, a pencil, a spirit level, a nail set, construction adhesive, a sealant gun and silicone sealant. Fixings depend on the wall. On plasterboard, use adhesive and, where possible, screw into timber noggins behind the board. On brick or concrete, use masonry nails or plugs and screws, drilling pilot holes first. Once the boards are fitted, fill the nail holes, then seal the top edge and corners with a colour-matched sealant, which hides the gap and keeps dust out.
Professional fitting and regulations
Replacing skirting board on its own does not normally need approval under the Building Regulations 2010 in England and Wales. Where skirting work forms part of a larger alteration, the wider project may fall within those Regulations, and in Scotland a building warrant under the Building (Scotland) Act 2003 may be needed for some work. In listed buildings, listed building consent is required under the Planning (Listed Buildings and Conservation Areas) Act 1990 before original features are altered, and this includes historic joinery. Check with your local authority before starting, particularly in older properties where the original woodwork is part of the building's character.
Estimating cost
The optional cost field multiplies the metres to buy by the price per metre you enter, so you can compare options quickly. Use prices from the supplier you plan to use, and remember that the estimate does not include delivery, fixings, adhesive or sealant.
Summary
The calculation is a chain of four steps: perimeter, deduction, waste and whole lengths. Done in order, it gives a reliable purchase figure for most rooms in a British home.
Frequently asked questions
How do I work out how much skirting board I need?
Start by calculating the room perimeter as 2 × (length + width). Next, subtract the clear width of each doorway. Multiply the result by 1.10 to add a 10% waste allowance for mitred corners, or by 1.15 for rooms with internal corners, recesses or built-in units. Finally, divide that total by the length of the boards you plan to buy and round up to a whole number of lengths. Measure each opening and wall on site before ordering, because older houses often have walls that are not square.
What height of skirting board should I choose?
It depends on the ceiling height and the style of the room. In modern flats and houses with ceilings around 2.4 m (about 8 ft), narrower boards keep the walls looking proportionate. In older houses with ceilings of 2.7 m (about 9 ft) or higher, taller boards usually look more in keeping. The most practical check is to match the existing skirting in a neighbouring room, particularly in period properties, where the original profile may be worth keeping.
What is the difference between MDF and solid wood skirting?
MDF is made from fine wood fibres bonded with resin. It is cheaper, smooth, straightforward to paint and well suited to dry rooms, but it swells if it gets wet and cannot be sanded and refinished many times. Solid wood, usually pine or oak, costs more and can be sanded, stained and repainted repeatedly, which suits period properties. Solid pine dents more easily than oak. For bathrooms and kitchens, PVC skirting is the better choice because it is unaffected by damp.
Do I need to allow for waste when buying skirting board?
Yes. Mitred corners, the ends of each run and offcuts that are too short to reuse all create waste that cannot be recovered. This calculator uses a 10% allowance for a simple rectangular room and a 15% allowance for rooms with internal corners, alcoves or built-in wardrobes. These are planning settings, not published standards, so measure each wall and adjust if the walls are irregular. Without a margin, it is common to run short when fitting the last section of a room, particularly if the batch you bought is no longer available.
How is skirting board fixed to the wall?
There are two main methods: construction adhesive and mechanical fixings. Adhesive is the usual choice on plasterboard, where the board can also be fixed into timber noggins for extra strength. Masonry walls, such as brick or concrete, usually take fixings with plugs or masonry nails, which give a firmer hold. Once the boards are fixed, fill the nail holes, then seal the joints and corners with a colour-matched silicone sealant or filler so the finish looks neat.
When should I hire a professional to fit skirting board?
Simple rectangular rooms with square walls are within reach of a competent DIYer with a mitre saw, construction adhesive and silicone sealant. Consider a fitter when walls are out of square, which is common in older houses, when the room has many internal corners, or when hardwood needs finishing on site. If the work is part of a larger project, check whether it falls within the Building Regulations 2010 in England and Wales, or needs a building warrant under the Building (Scotland) Act 2003 in Scotland. Listed buildings need listed building consent under the Planning (Listed Buildings and Conservation Areas) Act 1990 before original features are altered.
Related calculators
View all Paint & Coatings calculators →
By RivoCalc · Reviewed under our editorial methodology · Updated 10 June 2026
Results are planning estimates. Actual requirements depend on the room layout, cutting waste, the board lengths available and the price you enter. Measure on site before ordering.