Trim & Baseboards Calculator
How much trim do you actually need? This free trim and baseboards calculator gives DIYers and finish carpenters an instant material list — baseboard, crown, casing, chair rail, picture rail, and shoe — with linear feet, stick counts, fasteners, caulk, and crown compound-miter angles all in one screen.
Trim under-buys are the most common reason a finish carpenter has to come back a second day. Crown alone wastes 15% on cope cuts and compound miters, and casing math (with reveal and casing face width) trips up almost everyone the first time. The "17 LF per cased side" rule is fine for ordering — but the calculator shows the actual leg + head geometry so you can verify before you cut.
Built on the WMMPA/MMPA WM and LWM profile catalog, ANSI/AWI 0620 finish-carpentry tolerances, EPA TSCA Title VI / CARB Phase 2 emission limits for MDF, and RSMeans productivity baselines — runs in under a minute, no signup.
Trim & Baseboards Calculator
Estimate baseboard, crown, casing, chair rail, and shoe — with stick counts, fasteners, caulk, and crown compound-miter angles.
Room dimensions
Doors and windows
Trim types to include
Profile selection
Profile sizing rule of thumb: 3-1/4" base on 8 ft ceilings, 5-1/4" on 9 ft, 7-1/4"+ on 10 ft+. Casing reveal of 1/4" is the trade default.
Material and finish
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How to Use This Calculator
- Enter room dimensions: length, width, and ceiling height in feet.
- Add doors and windows: count, width, and height in inches. Doors deduct from baseboard run; crown is continuous (no deduction).
- Pick window casing style: picture frame (4-sided mitered) or stool & apron (3-sided + horizontal sill).
- Check the trim types to include: baseboard, base shoe / quarter round, crown, chair rail, picture rail, door casing (both sides), window casing.
- Pick profiles: baseboard (WM 623, WM 620, WM 618, ranch, craftsman), crown (WM 49, WM 47, WM 48, large, built-up), and casing (WM 356, WM 444, ranch, craftsman). Set the casing reveal — 1/4" is the default.
- Pick material and finish grade: MDF, finger-jointed pine, solid pine, poplar, oak, walnut/cherry/mahogany, PVC, or polyurethane — paint or stain grade. Stick length defaults to 16 ft.
- Click Calculate: see raw LF and waste-adjusted LF per trim line, stick count by stock length, fastener counts by gauge, caulk tubes, filler tubs, crown miter/bevel pair, and a cost roll-up (materials + consumables + labor).
How the Crown Compound-Miter Math Works
When crown is laid flat on the saw table — the JLC / Fine Homebuilding preferred method — both miter and bevel are set to a compound pair determined by spring angle and corner angle. The math comes from spherical trigonometry: tan(miter) = cos(spring) × tan(corner/2), and sin(bevel) = sin(spring) × cos(corner/2). For 38°/52° crown at a 90° corner: miter 31.62°, bevel 33.86° — the values stamped at the "crown molding" detents on most US compound saws. The calculator computes these for any spring/corner pair and recommends coping inside corners on paint-grade work, which tolerates drywall variance and never opens up.
Frequently Asked Questions
How many linear feet of baseboard do I need?
Linear feet of baseboard = room perimeter minus door rough openings. For a 12 ft × 14 ft room with one 32-inch door: perimeter is 2 × (12 + 14) = 52 LF, minus 2.67 ft per door = 49.33 LF before waste. Industry calculators (Alexandria Moulding, DIYCalculate, The Moulding Company) consistently use 3 ft per door for the deduction, accounting for the 32-inch rough opening plus jamb width covered by casing. Add 10% paint-grade waste for cuts and corners (15% if many corners or stain-grade), then round up to whole sticks at your stock length.
How do I calculate door and window casing in linear feet?
Per side of one pre-hung door: LF = 2 × (door height + reveal + casing width) + (door width + 2 × reveal + 2 × casing width), divided by 12 to get feet. For a 32 × 80-inch door with 2-1/4-inch casing and 1/4-inch reveal: each leg is 82.5 inches and the head is 37 inches, totaling 16.83 LF per side or 33.67 LF for both sides cased — the basis for the industry "17 LF per door" rule of thumb. Picture-frame window casing follows the same formula on all four sides: a 36 × 36-inch window needs about 13.7 LF; a 48 × 36-inch window needs about 15.7 LF.
What waste factor should I use for trim?
Per MMPA / Fine Homebuilding / JLC: 10% paint-grade waste for baseboard, casing, chair rail, picture rail, and shoe; 15% paint-grade waste for crown moulding (compound miters and cope practice cuts); +5 percentage points for stain-grade (color and grain selection from random board lots). Long open straight runs can run as low as 5–8% per WoodWeb consensus, but rooms with multiple inside corners and 2–3 doors hold at the 10–12% range. Built-up two-piece crown jumps to 15–20%.
What are the crown moulding miter and bevel angles?
When crown is laid flat on the saw table, set both miter and bevel to a compound pair determined by spring angle and corner angle. For a 90° corner: 38°/52° crown (most common stock) needs miter 31.62°, bevel 33.86° — the values stamped at the "crown molding" detents on most US compound saws. 45°/45° crown needs miter 35.26°, bevel 30°. The math is tan(miter) = cos(spring) × tan(corner/2), sin(bevel) = sin(spring) × cos(corner/2). For inside corners on paint-grade trim, cope rather than miter — coped joints compress over drywall variance and never open up.
What’s the difference between WM and LWM profile numbers?
WM (Wood Moulding) profile numbers come from the MMPA/WMMPA Combined Moulding Patterns catalog — the de-facto US standard reference. LWM ("lightweight" or "thinner") indicates a thinner-stock version of the same profile family — for example, WM 623 colonial baseboard is 9/16" × 3-1/4" while LWM 623 is 1/2" × 3-1/4" with the same face profile. Every major retailer (Home Depot, Lowe's, Menards) and distributor (Woodgrain, Metrie, Kelleher) cross-references these numbers, so a WM 49 crown from one supplier matches a WM 49 from another in profile geometry — though species and material may differ.
Can I use MDF baseboard in a bathroom?
MDF will warp and swell in wet areas, including bathrooms with poor ventilation, near sinks, and on slab floors below grade. Use PVC or cellular vinyl (Royal, Veranda, Azek) for bathroom baseboard and shoe — paintable with latex, mechanically fastened, and non-rotting. High-density polyurethane is also acceptable for crown in bathrooms. Solid wood (poplar, pine) tolerates short-term humidity better than MDF but still suffers in chronic wet conditions. All composite-wood trim sold in the US must meet EPA TSCA Title VI / CARB Phase 2 formaldehyde limits regardless of where it is installed.
How is base shoe different from quarter round?
Base shoe is 7/16" × 11/16" with a slightly oval profile — lower silhouette, more flexible over uneven floors. Quarter round is a true 3/4" × 3/4" quarter-circle — heavier presence, covers larger expansion gaps from floating LVP or hardwood. Both go in front of the baseboard along the floor, are nailed into the BASEBOARD (never into the floor — the floor must be free to expand), and are caulked to the baseboard at the top. Never caulk the bottom of the shoe to the floor — that pins the floor down and causes buckling.
What size finish nail do I need for trim?
16-gauge finish nails (1-1/4" to 2-1/2" length) are the all-around residential trim standard — used for baseboard, casing, crown, and chair rail through drywall into studs. 15-gauge for heavier 3/4"+ baseboard and door jambs. 18-gauge brads (5/8" to 2-1/8") for shoe and quarter round, mitered returns, base cap, and light crown. 23-gauge pins for delicate stops and glue-clamping. A common pro kit is one 16-ga finish nailer, one 18-ga brad nailer, and a 23-ga pinner. Spacing: every 16 inches on center to hit the studs.