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MetriFab

Baseboard and Trim Calculator: Feet and Pieces

Enter the room, the doors and the length of each piece.

Last reviewed 29 Oct 2026

Your measurements

Trim and room

Type of trim

Baseboard stops at doors. Crown and chair rail are assumed to run over them. You can change that below.

How to enter the walls

Wall to wall, along the base. For an L-shaped room use total wall length.

Doors and openings

Take doors and openings off the run

The opening between the jambs. A 32 in door is a typical interior size.

Stock, waste and corners

Length of each piece

Trim is often sold in 8, 10, 12 and 16 ft lengths. Check what your yard has.

10% is a common starting point. Allow more for crown or a lot of corners.

A plain rectangle has 4. Add one for each extra inside corner.

A plain rectangle has none. Count each chimney breast or wall that sticks out.

Leave at 0 if you only need the lengths.

Pieces to buy8 × 8 ft

Results

Pieces of baseboard to buy

8× 8 ft

= 64 ft of trim

38.67 ft of baseboard on the walls, or 42.53 ft with 10% extra. By total length: 6 pieces. Wall by wall: 8 pieces. The larger is used, because a piece cannot be shared between two walls without a joint.

Linear feet
38.67ft
44 ft around, less 5.33 ft of openings
With waste
42.53ft
10% extra
Corners
4 in, 0 out
Inside and outside
Cost
Not set
Enter a price per foot

Check before you cut

  • A wall is longer than one piece, so it needs a joint. Put each joint over a stud and cut it as a scarf joint so it stays closed.

Inside corners are usually coped or mitred and outside corners mitred. Cut each a little long and fit to the wall.

How this was calculated

Linear feet, waste and pieces, with your numbers.

  1. Step 1: Distance around the room

    2 × (length + width)

    = 2 × (12 + 10) ft
    = 44 ft

    Measure along the base of each wall, past any door or opening, then add them up.

  2. Step 2: Door and opening widths

    doors × door width + openings × opening width

    = 2 × 32 in + 0 × 36 in
    = 5.33 ft

    Baseboard stops at a door opening, so those widths come off the run.

  3. Step 3: Linear feet before waste

    distance around − openings

    = 44 − 5.33
    = 38.67 ft

    This is the length of trim on the walls.

  4. Step 4: Add the waste allowance

    linear feet × (1 + waste)

    = 38.67 × 1.1
    = 42.53 ft

    Extra for miter cuts, mistakes and bad ends. The percentage is your choice; 10% is a common starting point.

  5. Step 5: Pieces from the total length

    linear feet with waste ÷ stock length, rounded up

    = 42.53 ÷ 8
    = 6 pieces

    This assumes offcuts can be reused anywhere in the room.

  6. Step 6: Pieces wall by wall

    for each wall: wall length × (1 + waste) ÷ stock length, rounded up

    = 2 + 2 + 2 + 2
    = 8 pieces

    A piece cannot be shared between two walls without a joint, so each wall rounds up on its own. Door widths are not taken off here, because the doors could be on any wall.

  7. Step 7: Pieces to buy

    the larger of the two estimates

    = max(6, 8)
    = 8 pieces of 8 ft

    That is 64 ft of trim. Using the larger figure keeps you from running short.

In short

A 12 × 10 ft room has 44 ft of wall. With 2 doors of 32 in taken off that is 38.67 ft, or 42.53 ft with 10% extra. That is 6 pieces of 8 ft by total length, but 8 wall by wall, so buy 8.

The calculator gives the linear feet, the pieces to buy with waste, and the inside and outside corners.

Baseboard for common room sizes

Two 32 inch doors taken off, 10% extra and 8 ft pieces. The room sizes are examples; measure your own.

RoomLinear feetWith wasteBy total lengthWall by wallBuy
10 × 10 ft34.6738.13588
12 × 10 ft38.6742.53688
12 × 12 ft42.6746.93688
14 × 12 ft46.6751.33788
16 × 14 ft54.6760.1381010

Worked out with the formulas on this page. Wall by wall does not take off doors, because the doors could be on any wall.

Worked example: 12 × 10 ft room, 2 doors, 8 ft pieces

10% extra for waste, baseboard with the door openings taken off.

  1. Step 1: Distance around the room

    2 × (length + width)

    = 2 × (12 + 10) ft
    = 44 ft

    Measure along the base of each wall, past any door or opening, then add them up.

  2. Step 2: Door and opening widths

    doors × door width + openings × opening width

    = 2 × 32 in + 0 × 36 in
    = 5.33 ft

    Baseboard stops at a door opening, so those widths come off the run.

  3. Step 3: Linear feet before waste

    distance around − openings

    = 44 − 5.33
    = 38.67 ft

    This is the length of trim on the walls.

  4. Step 4: Add the waste allowance

    linear feet × (1 + waste)

    = 38.67 × 1.1
    = 42.53 ft

    Extra for miter cuts, mistakes and bad ends. The percentage is your choice; 10% is a common starting point.

  5. Step 5: Pieces from the total length

    linear feet with waste ÷ stock length, rounded up

    = 42.53 ÷ 8
    = 6 pieces

    This assumes offcuts can be reused anywhere in the room.

  6. Step 6: Pieces wall by wall

    for each wall: wall length × (1 + waste) ÷ stock length, rounded up

    = 2 + 2 + 2 + 2
    = 8 pieces

    A piece cannot be shared between two walls without a joint, so each wall rounds up on its own. Door widths are not taken off here, because the doors could be on any wall.

  7. Step 7: Pieces to buy

    the larger of the two estimates

    = max(6, 8)
    = 8 pieces of 8 ft

    That is 64 ft of trim. Using the larger figure keeps you from running short.

Before you buy

  • Measure along the base of each wall, not along the middle. Walls are rarely square, so measure each one.
  • A wall longer than one piece needs a joint. Put it over a stud and cut it as a scarf joint so it stays closed as the wood moves.
  • Offcuts from one wall can often be used on a short wall or beside a door. The wall by wall estimate does not count on that, which is why it can come out higher.
  • Crown corners are cut at compound angles. Make test cuts on scrap and buy a spare piece.
  • Trim comes in different lengths and the lengths on offer vary by yard, so check what is in stock before you set the piece length.

Baseboard and trim: common questions

Doors, waste, joints and pieces.

How do you calculate how much baseboard you need?

Add up the length of every wall, take off the width of each door opening, then add extra for waste. A 12 by 10 ft room is 44 ft around. Two 32 inch doors take off about 5.3 ft, leaving 38.7 ft, and 10% extra makes 42.5 ft. Divide by the piece length and round up to get the pieces.

Why does the calculator buy more pieces than the total length suggests?

Because a piece cannot be shared between two walls without a joint. The total length for the default room needs 6 pieces of 8 ft, but each wall needs 2 pieces on its own, which makes 8. The calculator works out both and uses the larger, so you are less likely to run short.

Do I subtract doors for crown molding and chair rail?

Baseboard stops at a door opening, so the calculator subtracts doors for baseboard. Crown is assumed to run over doors, so nothing is taken off. Chair rail is set the same way. If your chair rail stops at the casing, change the switch to take the openings off.

How much extra trim should I buy?

10% is a common starting point for baseboard. Many people allow more for crown, or for a room with many corners or walls longer than one piece. It is your choice: the calculator uses whatever percentage you set. Where a wall is longer than one piece, put the joint over a stud and cut it as a scarf joint.