How to use this calculator
- 1Measure the width of the wall and the height you want to cover.
- 2Enter the area of any large openings such as doors or big windows.
- 3Choose the panel type, or enter your own panel length and width. For boards, use the cover width.
- 4Choose whether the panels run up the wall or along it.
- 5Keep about 10 % spare, or change it to suit your wall.
The formula
- 01Lines of panels = wall width (or height, for horizontal boards) ÷ panel width, rounded up
- 02Whole panels per line = height (or width) ÷ panel length, rounded down
- 03Leftover per line is cut from spare panels: pieces per panel = panel length ÷ leftover, rounded down
- 04Panels = (lines × whole panels + lines ÷ pieces per panel, rounded up) × number of walls
- 05Panels to buy = panels × (net area ÷ wall area) × (1 + spare %), rounded up
Panels are cut to fit, so dividing the wall area by the panel area can leave you short when the height does not suit the panel length. This calculator counts panels the way they are fitted: each column (or row) gets whole panels, and the leftover piece at the top or end is cut from extra panels, fitting as many pieces into each panel as its length allows. Half-height wainscoting works the same way — one tall panel can give two or more short pieces.
Tongue-and-groove and shiplap boards overlap, so each board covers less than its full width. Always use the cover width (also called face or exposed width). Large openings reduce the count in proportion to their area; small windows and sockets do not, because you still cut panels around them.
Worked example
A 3 m wide wall, 2.4 m high, covered with 2.4 m × 1,000 mm wet-wall panels takes 3 full-height panels side by side.
With 10% spare for a cutting mistake, buy 4 panels.
Tips before you buy
- Start with a full panel at the most visible corner and plan the cut pieces for the least visible corner or behind furniture.
- Check the wall is flat and dry first. Uneven walls need battens, which also changes the depth at window reveals and sockets.
- Let wood and MDF panelling acclimatise in the room for a day or two before fitting, as the maker advises.
- If your ceiling is higher than the panel length, check whether longer panels (for example 2.7 m) are made — it can save a joint in every column.
Frequently asked questions
How do I calculate how many wall panels I need?
Divide the wall width by the panel width and round up to get the number of panels side by side. If the wall is taller than a panel, add pieces for the gap at the top, cut from extra panels. Then add about 10 % spare.
What is cover width?
It is the width a board actually covers once fitted. Tongue-and-groove and shiplap boards overlap, so a board sold as 100 mm or 6 in nominal may cover only about 88 mm or 5 in of wall. Using the full width would leave you short.
How much extra shiplap or tongue and groove should I buy?
About 10 % for a simple wall, more for walls with several openings or angled ceilings. Boards can have defects, and cuts around windows and sockets add up.
How much wall does one panel cover?
A 2400 × 1000 mm shower panel covers 2.4 m², an acoustic slat panel of 2400 × 600 mm covers 1.44 m², and a 4 × 8 ft sheet covers 32 ft². The number you need still depends on how the panels fit your wall, which this calculator works out.
Should panelling go vertical or horizontal?
Sheet panels, slat panels and shower panels are usually fitted vertically. Shiplap is often horizontal and tongue-and-groove either way. Horizontal boards can make a room feel wider; vertical boards make it feel taller.
Also searched as: wall paneling calculatorshiplap calculatortongue and groove calculatorwainscoting calculatorshower wall panel calculatorcladding calculator
Sources
- PVC wet-wall panel size 1000 × 2400 mm (2.4 m² each) — example UK product
- Acoustic slat wall panel 2400 × 600 mm — B&Q
- Shiplap and tongue-and-groove exposed face (6 in nominal → 5 in) and 10 % waste — Buffalo Lumber
- Tongue-and-groove matchboard 100 mm wide, about 88 mm cover, 2.4 m — Timber Yard Direct
Formulas last reviewed: September 30, 2026 ·How we check our formulas