How to measure for baseboard
Run the tape along the floor, not at waist height, because a wall that leans or bows is what the trim has to sit against. Measure every wall from corner to corner and write the figures on a sketch of the room, wall by wall, rather than adding them straight away. You need that sketch to plan your sticks.
Measure the gap each door leaves, including the frame, and take it off. Do not take anything off for windows. Baseboard carries on underneath them, and forgetting that is the classic way to come up short. Closets count as well, and a small one can add ten or twelve feet of wall.
Check what your store carries before you plan. Common stock lengths are 8, 12 and 16 feet, but a particular profile may come in only one of them, and a 16 foot stick needs a way of getting home.
A worked example
Here is a 14 by 12 foot bedroom with one 36 inch door, in 16 foot sticks. These lines come from the same formula the calculator above runs.
14 by 12 ft room, one door, 16 ft sticks
- Walls: 2 × (14 + 12) = 52 ft
- Less the door: 52 − 3 = 49 ft
- With 10% extra: 49 × 1.1 = 53.9 ft
- In 16 ft sticks: 4 sticks
Change that to 8 foot sticks and it becomes 7 sticks, with 4 joints on the long walls where a single 16 foot piece would have had none. Joints in trim show, so most people pay a little more for the long stick on a wall that faces you when you walk in.
Casing is worked out separately. A 36 by 48 inch window with 3 inch casing takes 16 feet, because each mitred piece is longer than its side by the casing width at both ends. If you are repainting at the same time, the paint calculator covers the walls, and the flooring calculator is measured off the same room.
Baseboard for common rooms
These are for plain rectangular rooms with 36 inch doors and 10 percent extra. Treat them as a check on your own number. Your real room has closets and bump-outs these do not.
| Room | Wall to cover | To buy | 16 ft sticks | 8 ft sticks |
|---|---|---|---|---|
| Small bedroom, 10 × 10, 1 door | 37 | 40.7 | 4 | 6 |
| Bedroom, 12 × 12, 1 door | 45 | 49.5 | 4 | 7 |
| Main bedroom, 14 × 12, 1 door | 49 | 53.9 | 4 | 7 |
| Living room, 16 × 12, 2 doors | 50 | 55.0 | 4 | 7 |
| Large living room, 20 × 14, 2 doors | 62 | 68.2 | 5 | 9 |
| Kitchen, 12 × 8, 2 doors | 34 | 37.4 | 3 | 5 |
Mistakes that leave you a stick short
- Treating it as a total. Dividing 52 feet by 16 says four sticks, but you cannot join offcuts everywhere. Two 14 foot walls use two whole sticks and leave offcuts of only 2 feet each.
- Deducting windows. Baseboard runs under a window. Only door openings come off.
- Forgetting closets. Measure them with the room, or buy them a second trip later, possibly from a new batch that does not match.
- Assuming 16 foot sticks exist. Plenty of profiles come only in 8 foot lengths in the store, which changes both the count and where the joints fall.
- No allowance for scarf joints. Where two sticks meet on a long wall, each is cut at an angle and loses a little length. That comes out of your 10 percent.
Questions
How much baseboard do I need for a 12x12 room?
A 12 by 12 room with one 36 inch door needs about 49.5 feet with 10 percent extra. The walls add to 48 feet, the door takes off 3, and the extra brings 45 feet up to 49.5. That is four 16 foot sticks.
How do I measure for baseboard?
Measure each wall at the floor, from corner to corner, and add them up. Then take off the width of each door opening, because baseboard stops at the casing. Do not take off windows, since baseboard runs under them.
How much extra trim should I buy?
Buy about 10 percent extra, which is what Alexandria Moulding suggests to be safe. Go higher if the room has many short walls or outside corners, since each one means another cut that can go wrong.
What lengths does baseboard come in?
Baseboard commonly comes in 8, 12 and 16 foot lengths, but it varies by profile and by store. Many stores carry only 8 foot sticks in some profiles, and home delivery may be needed for 16 foot ones, so check before you plan your cuts.
How much baseboard do I need per square foot of house?
There is no reliable figure per square foot, because the answer depends on how many rooms the house is split into, not on its floor area. Two houses of 1,500 square feet can differ a lot in wall length. Measure each room and add them up.
How many inside and outside corners will I cut?
A closed room with square corners always has four more inside corners than outside corners. A plain room has 4 inside and none outside. A room with a chimney breast sticking out has 2 outside corners, and so 6 inside.
This baseboard figure is a planning estimate for a room with square corners and walls you measured yourself. Scarf joints, a wall out of true and a bad cut all use extra trim. Stock lengths vary by profile and by store, so check with your supplier what comes in the length you want before you plan around it.
Sources and review
- Moulding FAQ on product page 02189, Alexandria Moulding, no date shown, read November 2026.
- Alexandria Mouldings collection FAQ, Windsor Plywood, no date shown, read November 2026.
- Trim and molding calculator, Inch Calculator, no date shown, read November 2026.
Checked in November 2026. Spotted a wrong number? Report it and it goes in the corrections log.
How this is calculated
Every figure below is read from the code that produces the answer, so what is written here is what the calculator ran. The constants were last checked against their sources in November 2026.
The arithmetic
Baseboard to buy
Feet = (2 × (Length + Width) + Extra wall − Door openings) × (1 + Extra ÷ 100)
- Door openings
- Number of doors times the width of each, in feet
- Extra
- Percent added for cuts and mistakes
Worked through: 2 × (14 + 12) = 52, 52 − 3 = 49, 49 × 1.1 = 53.9 ft
Inside corners
Inside corners = 4 + Outside corners
- 4
- The extra turns any closed square-cornered room has
Worked through: 4 + 2 = 6 inside corners
The constants, and where they come from
SUGGESTED_WASTE_PERCENT
Published range, narrowedExtra to add for waste, in percent
Applies to: Interior moulding sold in sticks
Source: Moulding FAQ on product page 02189, Alexandria Moulding, no date on the page, read 2026-11.
A manufacturer's advice, undated on the page. Inch Calculator declines to give a figure and calls it a judgment call.
COMMON_STOCK_FEET
Published range, narrowedCommon stick lengths for baseboard, in feet
- 0
- 8
- 1
- 12
- 2
- 16
Applies to: Common retail stock. Lengths vary by profile and by store
Source: Alexandria Mouldings collection FAQ, Windsor Plywood, no date on the page, read 2026-11.
A retailer's FAQ says common stock lengths are 8, 12 and 16 feet. The Metrie catalog confirms 8 and 16 foot baseboard rows.
INCHES_PER_FOOT
DefinitionalInches in one foot
Applies to: Definitional, everywhere
True by definition, so there is nothing to cite. The derivation is below.
Twelve inches make a foot by definition, so door widths in inches are divided by 12.
INSIDE_MINUS_OUTSIDE
DefinitionalHow many more inside corners than outside corners a closed square-cornered room has
Applies to: A closed room whose corners are all right angles
True by definition, so there is nothing to cite. The derivation is below.
Walking all the way round a room you turn 360 degrees, and each inside corner minus each outside corner is 90, so the difference is 4.
SHORTEST_USABLE_OFFCUT_FEET
ModelledThe shortest offcut kept for use on a short wall, in feet
Applies to: Painted baseboard cut with a miter saw
No published figure exists for this. It is derived, and the derivation is below rather than a citation to something that does not say it. Last checked in November 2026.
Our own judgment, since no manufacturer publishes a figure. Shorter than a foot is hard to hold safely at a miter saw and rarely fits anything.
What the labels mean
- Published range, narrowed:
- a source publishes a range and this calculator uses a representative value from it.
- Definitional:
- true by definition, like the number of inches in a foot, so there is nothing to cite.
- Modelled:
- derived rather than measured, and the derivation is shown.
If a figure here looks wrong, it may be. Tell us what you found and we will check it against the source and publish a correction if it needs one. How constants are chosen and how often they are reviewed is set out in our methodology.
How to use the baseboard and trim calculator
- 1
Measure the room wall to wall, and add any closet or alcove as extra wall
- 2
Count the doors and measure the width of the opening
- 3
Choose the stick length your store stocks in the profile you want
- 4
Read the feet to buy and the number of sticks
- 5
Open the casing section if you are trimming doors and windows too
What this calculator assumes
Every estimate here rests on the assumptions below. Where your job differs from one of them, the figure will differ too.
- The room is a rectangle, plus any extra wall you add for closets or alcoves
- Door openings are the only gaps. Baseboard runs under a window, so windows are not deducted
- A door opening is deducted from the longest wall first when planning sticks
- An offcut of one foot or longer is kept for a short wall
Pro tips
- Plan the longest walls first so a joint falls where a chair or a sofa will hide it
- Cut scarf joints over a stud so both ends can be nailed
- Prime and paint the sticks before you cut them, and touch up after