How Much Trim Do You Need?
Enter your room size and doors — get linear feet and sticks to buy for baseboard, crown molding, chair rail, and casing in one order.
Last updated: June 10, 2026
Room Size (ft)
Door openings are subtracted from baseboard and chair rail runs automatically.
Trim to Include
Baseboard— floor line
Crown molding— ceiling line
Chair rail— mid-wall
Door & window casing— around openings
Trim Order Summary
7
sticks of 8 ft trim to buy
Baseboard7 sticks · 49.5 linear ft
Total Linear Feet49.5 lf
Tip: buy one extra stick for miscuts and future repairs.
12×12 ft room · 48 ft perimeter · 3 ft of door openings subtracted · 10% waste included
Worked Examples
12×12 Bedroom — Baseboard Only, 1 Door
- Perimeter: 2 × (12 + 12) = 48 ft, minus 3 ft door opening = 45 ft
- With 10% waste: 45 × 1.1 = 49.5 linear feet
- Sticks: 49.5 ÷ 8 = 6.2 → 7 sticks of 8-ft baseboard
15×20 Living Room — Baseboard + Crown, 2 Doors
- Perimeter: 70 ft · Baseboard: (70 − 6) × 1.1 = 70.4 lf → 9 sticks
- Crown runs over doors: 70 × 1.1 = 77 lf → 10 sticks
- Order: 19 sticks of 8-ft trim, 147.4 lf total
12×14 Bedroom — Baseboard + Casing, 1 Door, 2 Windows
- Baseboard: (52 − 3) × 1.1 = 53.9 lf → 7 sticks
- Casing: 1 door × 17 + 2 windows × 14 = 45 × 1.1 = 49.5 lf → 7 sticks
- Order: 14 sticks, 103.4 lf total
Which Stick Length Should You Buy?
| Stick Length | Best For | Notes |
|---|---|---|
| 8 ft | Small rooms, walls under 8 ft | Standard stock everywhere; fits in most cars |
| 10–12 ft | Most bedrooms and living rooms | Covers typical walls in one piece — fewer joints |
| 16 ft | Long walls, open floor plans | One-piece runs with no joints; needs delivery or a truck |
Joints in the middle of a wall are the most visible trim flaw. If a wall is longer than your stick, step up a length — or plan the joint over a stud and cut both ends at matching 45° angles.
Casing Coverage Guide
| Opening | Casing Needed | Notes |
|---|---|---|
| Door, one side | ~17 linear ft | Two 7-ft legs + 3.5-ft head for a 36" × 80" door |
| Door, both sides | ~34 linear ft | Count the door twice if you're trimming both rooms |
| Window, 3×4 ft | ~14 linear ft | All four sides, standard picture-frame casing |
| Larger window | Window perimeter + 10% | Measure width and height, add all four sides |
Frequently Asked Questions
A 12×12 room has a 48 ft perimeter. With one standard door subtracted (3 ft) and 10% waste, you need about 49.5 linear feet of baseboard — that's 7 sticks of 8-ft trim. Add crown molding and you need another 53 linear feet (7 more sticks), since crown runs over door openings.
Yes. Baseboard and chair rail stop at door openings, so subtract each door's width from the room perimeter — about 3 ft per standard door. Crown molding is different: it runs along the ceiling line over doors, so use the full perimeter. This calculator handles both automatically.
10% is the standard waste allowance for trim. It covers miter cuts at corners, miscuts, and short offcuts you can't reuse. Go up to 15% for rooms with many corners or bump-outs, and you can drop to 5% for one simple straight run. Pros also keep one spare stick for future repairs.
Most stores sell trim in 8, 10, 12, and 16 ft sticks. 8 ft is what you'll find on every shelf, but longer sticks mean fewer joints — a 14 ft wall covered by one 16 ft stick looks better than two joined pieces. Pick your stick length in Advanced settings to see how many to buy.
A standard 36" × 80" door needs about 17 linear feet of casing per side — two 7-ft legs and a 3.5-ft head with cutting room. A typical 3×4 ft window cased on all four sides needs about 14 linear feet. If you're casing both sides of a door, double the door figure.
Trim and molding mean the same thing — decorative boards that cover joints and edges. Baseboard is the trim at the floor line, casing surrounds doors and windows, chair rail runs mid-wall, and crown molding sits at the ceiling. All are estimated the same way: linear feet plus waste.
Measure each wall at floor level with a tape measure and add the lengths together. For a simple rectangular room, length and width are all this calculator needs — it figures the perimeter for you. For L-shaped rooms or bump-outs, add up all the wall sections, then enter half the total as Length and half as Width. Don't subtract windows for baseboard; door openings are handled automatically.