How much baseboard do I need for a 15×20 room?

Data checked October 2026

Short answer

A 15 × 20 ft room with one 36 in door needs 67 linear ft of baseboard — 10 × 8 ft, 7 × 12 ft, 5 × 16 ft with 10% for copes and miters.

Math: 2 × (15 + 20) = 70 ft of wall − 3 ft for the door = 67 ft; × 1.10 = 73.7 ft to buy.
Corners: 4 inside corners to cope or miter and 2 square ends at the door casing.
Fasteners and finish: about 102 finish nails (two per stud at 16 in), 2 tubes of caulk for the top edge, and 1 quart of trim paint for two coats on 5¼ in base.
Cost: about $135 in MDF, caulk and paint; a pro adds about $427 at $6.38 per linear ft (Angi range $5–$7.75).
15×20 is a living room; its 20 ft walls need a splice with any stock length.

Adjust it to your exact job

Rooms

Length

= 20' · 6.1 m

Width

= 15' · 4.57 m

Openings & extras

Door openings

Opening width

Measure openings casing to casing. A door between two rooms you're trimming counts twice — once for each side.

No baseboard

Extra wall

No baseboard: cabinets, tubs, built-ins. Extra wall: closet returns, jogs and bump-outs the rectangles miss.

Outside corners

Corners that stick out into the room, like a hallway jog or a chimney bump-out.

Stock & finish

Piece length

Longer pieces mean fewer splices; 8 ft fits in most cars.

Extra for copes & miters

Caulk and paint

Baseboard height

Coats

Add quarter round

Covers the expansion gap when baseboards stay in place over a new floor.

You need

7× 12 ft pieces

67 ft of wall + 10% for copes and miters = 74 ft · 4 scarf joints

Cut list — each bar is one 12 ft stick

Plus 1 spare stick from the 10% allowance for re-cuts.

Linear feet: 67ftwalls minus openings
Inside corners: 4cope or miter
Outside corners: 0miter both pieces
Finish nails: 1022 per stud, 16 in apart
Caulk: 2tubes55 ft per tube
Paint: 1 qt29 sq ft × 2

Which length to buy

Baseboard pieces by stock length
Length	Pieces	Splices	Offcuts	Cost
8 ft	10	6	13 ft	$96.00
12 ft	7	4	17 ft	$101
16 ft	5	2	13 ft	$96.00

4 walls are longer than a 12 ft stick. Join pieces with a 45° scarf joint over a stud, not a butt joint.

Cope the inside corners

Run one piece square into the corner and cope the other to its profile; a coped joint hides small gaps better than a miter when the corner isn't square. Miter outside corners at 45° and join long walls with a scarf joint.

Shopping list

7 pieces Baseboard, 12 ft lengths67 linear ft + 10% for copes and miters$101
102 nails Finish nails (2 per stud)15- or 16-gauge, long enough to reach the studs
2 tubes Paintable caulk, 10.1 oztop edge, 3/16 in bead$9.38
1 qt Semi-gloss trim paint, quart$24.59

Estimated total$135

Cost estimate

Tap a price to use your store's

MDF baseboard, 12 ft
7 pieces × $MDF typically $1.00–$1.40 per linear ft
$101
Paintable caulk
2 tubes × $
$9.38
Trim paint, quart
1 qt × $
$24.59

Materials total$135

MDF: Angi 2026 range. Caulk and Sherwin-Williams Emerald semi-gloss: online prices, October 2026. Tap any price to enter your store's.

Hiring a pro? Installed cost

Labor per linear ft

Installation labor
67 linear ft × $6.38
$427

Materials: $135
Labor & extras: $427
Installed total: $562

Labor: Angi 2026 ($5–$7.75 per linear ft). Painting and removing old trim are usually quoted separately.

Did this answer your question?

Compare

Baseboard for a 15×20 room by piece length

Piece length	Pieces	Splices	Offcuts	MDF cost
8 ft	10	6	13 ft	$96.00
12 ft	7	4	17 ft	$101
16 ft	5	2	13 ft	$96.00

How this was worked out

No stock length covers the 20 ft walls in one piece, so plan 2 scarf joints — cut both ends at 45° and land the joint on a stud.

Measure the actual door opening from casing edge to casing edge; a wider opening or a run of cabinets comes straight off the linear feet.

The full method, material data and tips are on the main baseboard calculator page.

Similar jobs

Other sizes people check

Sources

Data behind this answer

Lowe's Moulding Installation Guide — Baseboard — nail into studs every 16–18 in; cope or miter inside corners, miter outside corners, scarf-join long walls · checked October 2026
DAP Alex Plus technical bulletin — 10.1 fl oz cartridge = 55 linear ft at a 3/16 in bead · checked October 2026
Sherwin-Williams Emerald Interior — product data and prices — 350–400 sq ft per gallon per coat; semi-gloss $24.59 per quart, $63.89 per gallon (Oct 2026) · checked October 2026
Angi — baseboard installation cost (2026) — MDF $1.00–$1.40 per linear ft; labor $5–$7.75 per linear ft · checked October 2026
Floor & Decor underlayment and molding pages (live) — EZ Foam 100 sq ft $40.49; 15 lb felt 432 sq ft $32.97; 94 in quarter round $3.35 · checked October 2026

Short answer

A 15 × 20 ft room with one 36 in door needs 67 linear ft of baseboard — 10 × 8 ft, 7 × 12 ft, 5 × 16 ft with 10% for copes and miters.

Math: 2 × (15 + 20) = 70 ft of wall − 3 ft for the door = 67 ft; × 1.10 = 73.7 ft to buy.

Corners: 4 inside corners to cope or miter and 2 square ends at the door casing.

Fasteners and finish: about 102 finish nails (two per stud at 16 in), 2 tubes of caulk for the top edge, and 1 quart of trim paint for two coats on 5¼ in base.

Cost: about $135 in MDF, caulk and paint; a pro adds about $427 at $6.38 per linear ft (Angi range $5–$7.75).

15×20 is a living room; its 20 ft walls need a splice with any stock length.

Adjust it to your exact job

Rooms

Length

= 20' · 6.1 m

Width

= 15' · 4.57 m

Openings & extras

Door openings

Opening width

Measure openings casing to casing. A door between two rooms you're trimming counts twice — once for each side.

No baseboard

Extra wall

No baseboard: cabinets, tubs, built-ins. Extra wall: closet returns, jogs and bump-outs the rectangles miss.

Outside corners

Corners that stick out into the room, like a hallway jog or a chimney bump-out.

Stock & finish

Piece length

Longer pieces mean fewer splices; 8 ft fits in most cars.

Extra for copes & miters

Caulk and paint

Baseboard height

Coats

Add quarter round

Covers the expansion gap when baseboards stay in place over a new floor.

You need

7× 12 ft pieces

67 ft of wall + 10% for copes and miters = 74 ft · 4 scarf joints

Cut list — each bar is one 12 ft stick

Plus 1 spare stick from the 10% allowance for re-cuts.

Linear feet: 67ftwalls minus openings
Inside corners: 4cope or miter
Outside corners: 0miter both pieces
Finish nails: 1022 per stud, 16 in apart
Caulk: 2tubes55 ft per tube
Paint: 1 qt29 sq ft × 2

Which length to buy

Baseboard pieces by stock length
Length	Pieces	Splices	Offcuts	Cost
8 ft	10	6	13 ft	$96.00
12 ft	7	4	17 ft	$101
16 ft	5	2	13 ft	$96.00

4 walls are longer than a 12 ft stick. Join pieces with a 45° scarf joint over a stud, not a butt joint.

Cope the inside corners

Shopping list

7 pieces Baseboard, 12 ft lengths67 linear ft + 10% for copes and miters$101
102 nails Finish nails (2 per stud)15- or 16-gauge, long enough to reach the studs
2 tubes Paintable caulk, 10.1 oztop edge, 3/16 in bead$9.38
1 qt Semi-gloss trim paint, quart$24.59

Estimated total$135

Cost estimate

Tap a price to use your store's

MDF baseboard, 12 ft
7 pieces × $MDF typically $1.00–$1.40 per linear ft
$101
Paintable caulk
2 tubes × $
$9.38
Trim paint, quart
1 qt × $
$24.59

Materials total$135

MDF: Angi 2026 range. Caulk and Sherwin-Williams Emerald semi-gloss: online prices, October 2026. Tap any price to enter your store's.

Hiring a pro? Installed cost

Labor per linear ft

Installation labor
67 linear ft × $6.38
$427

Materials: $135
Labor & extras: $427
Installed total: $562

Labor: Angi 2026 ($5–$7.75 per linear ft). Painting and removing old trim are usually quoted separately.

Piece length

Pieces

Splices

Offcuts

MDF cost

8 ft

13 ft

$96.00

12 ft

17 ft

$101

16 ft

13 ft

$96.00

How this was worked out

No stock length covers the 20 ft walls in one piece, so plan 2 scarf joints — cut both ends at 45° and land the joint on a stud.

Measure the actual door opening from casing edge to casing edge; a wider opening or a run of cabinets comes straight off the linear feet.

The full method, material data and tips are on the main baseboard calculator page.