Enter the room size, the number and width of the door openings and the length of the pieces you will buy. The calculator shows how much trim you need in total and how many pieces to buy. Choose baseboard or quarter round: the sum is the same, only the label changes.
This calculator needs JavaScript. The formula and a worked example are below.
How to use the baseboard calculator
Measure the room’s length and width. If you are also trimming a closet or alcove, add its wall length in the extra field. Count the doorways and enter their width. The trim does not cross door openings, so they are taken away from the total.
The formula
Wall run = 2 × (length + width) + extra wall. Length to cover = wall run − (openings × opening width). With waste = length to cover × (1 + waste). Pieces = that length ÷ piece length, rounded up.
Worked example
A 15 ft by 12 ft room has 54 ft of wall. Two 3 ft doorways take away 6 ft, leaving 48 ft. A 10% allowance makes it 52.8 ft. With 8 ft pieces you need 52.8 ÷ 8 = 6.6, so buy 7 pieces. With 12 ft pieces you would need 5.
Why waste matters for trim
Trim is cut at corners and joined along the wall, and every miter uses up extra length. Short offcuts often cannot be reused. Longer pieces mean fewer joints, but only if they are straight and you can carry them home and into the room.
Baseboard versus quarter round
Baseboard covers the gap where the wall meets the floor. Quarter round is small trim added at the bottom of the baseboard to hide the gap above a floating floor. Read the quarter round molding guide for sizes and installation mistakes.
Frequently asked questions
Do I need to measure each wall?
For a rectangular room, length and width are enough. For irregular rooms, add each wall and enter the total as the extra wall length.
Should I buy extra?
A waste allowance of around 10% is a good starting point, and more helps if your room has many corners.
Should I caulk the top edge?
Caulk is often used to close gaps between trim and the wall. Read whether to caulk between baseboard and vinyl flooring before sealing the bottom edge.
Related guides
See quarter round molding and caulking baseboard and vinyl floor. If you are also laying a new floor, use the flooring calculator.