Reading the results
The two quantity outputs answer different questions: linear meters is the pricing figure, board count is what actually goes in the cart.
| Result | What it includes | Use it for |
|---|---|---|
| Baseboard to buy | Perimeter minus doorways, plus 10% waste | Comparing per-meter prices between profiles |
| Boards needed | The run divided by stock length, rounded up | The purchase quantity at the store |
| Estimated cost | Boards × price per board | Budgeting (only shown when a price is entered) |
- The 0.9 m doorway deduction is a typical interior door opening width; unusually wide openings (double doors, cased openings) remove more and can be counted as two doorways.
- Rooms with many corners consume more waste than long simple rooms — every inside corner is coped or mitered and every outside corner mitered, so complex floor plans may justify 15% waste rather than 10%.
What does a baseboard calculator do?
A baseboard calculator converts a room's perimeter into the length of baseboard molding to buy. Baseboard (called skirting board in the UK) runs along every wall except across doorways, so the calculation starts from the perimeter, deducts a typical doorway width of about 0.9 m for each door opening, and then adds a waste allowance — 10% is the standard finish-carpentry convention — because every inside corner, outside corner and splice consumes length in angled cuts.
Because baseboard is sold in fixed stock lengths (2.4 m is common; 3 m, 3.6 m and 4.9 m lengths also exist by market), the calculator also converts the required run into a board count by dividing the total by the stock length and rounding up. Buying by board count rather than raw meters matters on real jobs: long walls look best covered by a single board without splices, which can push the practical count above the theoretical minimum.
How to use this baseboard calculator
- Measure the room perimeter in meters by adding all wall lengths at floor level.
- Enter the number of doorways — about 0.9 m is deducted for each, since baseboard does not cross door openings.
- Enter the stock length your supplier sells (2.4 m is common) and, optionally, the price per board.
- Read the linear meters to buy (waste included), the number of boards, and the estimated cost if a price was entered.
The formula behind baseboard quantity
The required run equals the perimeter minus 0.9 m per doorway, multiplied by 1.10 to add the standard 10% cutting-waste allowance. The board count divides that total by the stock length and rounds up to whole boards, and the cost multiplies boards by the entered price.
Worked example: a room with an 18 m perimeter and 2 doorways needs (18 − 2 × 0.9) × 1.1 = 17.82 ≈ 17.8 m of baseboard. At a 2.4 m stock length that is ceil(17.82 ÷ 2.4) = 8 boards.
Common mistakes
- Buying the exact perimeter length with no waste allowance — miters at every corner and unusable short offcuts routinely consume close to 10% of the material.
- Forgetting that baseboard stops at doorways — skipping the deduction inflates the order, while forgetting a doorway in the count works the other way.
- Planning splices in the middle of prominent walls — where possible, each wall should be covered by a single board, which can require buying longer stock than the minimum board count suggests.
- Ignoring the profile height when replacing baseboard — new baseboard shorter than the old line leaves unpainted wall and flooring gaps exposed.
Questions fréquentes
How much baseboard do I need for a room?
Add up the wall lengths to get the perimeter, subtract about 0.9 m for each doorway, and add 10% for cutting waste. An 18 m perimeter with 2 doorways works out to about 17.8 m of baseboard to buy.
How many 2.4 m boards is 17.8 meters of baseboard?
Divide the total by the stock length and round up: 17.82 ÷ 2.4 = 7.4, so 8 boards. Rounding up is essential because offcuts from one wall often cannot be reused on another.
Why add 10% waste to baseboard?
Every corner joint consumes length: inside corners are coped or mitered and outside corners mitered, both cutting the board at 45° rather than square. Together with unusable short offcuts, this typically consumes close to 10% of the material on a standard room, and more on complex floor plans.
Do I deduct windows from a baseboard measurement?
No. Baseboard runs at floor level, so only floor-level openings — doorways, cased openings, floor-to-ceiling built-ins — interrupt it. Windows above floor level have no effect on the quantity.
Should baseboard be installed before or after flooring?
Common practice is flooring first, then baseboard, so the baseboard covers the flooring's expansion gap at the wall. With carpet, baseboard is often installed first, held slightly above the subfloor so the carpet can be tucked underneath.
Références
- Architectural Woodwork Institute (AWI) — Architectural Woodwork Standards: interior trim materials and installation quality standards.
- Standard finish-carpentry estimating practice — per-doorway deductions and the 10% trim waste convention used across the trade.
- Flooring manufacturer installation instructions — expansion-gap requirements at walls that baseboard and shoe molding are used to cover.