Carpenter Calculator: Ft-In

Carpenter Calculator is a feet-inch-fraction construction calculator built for the job site: a dedicated ft-in keyboard, exact fraction math, stairs, rafters, wall framing, board feet and cut optimizers for boards and sheets. Works offline; no account.

Free with ads. Pro removes them (subscription or one-time purchase) and lifts a few limits such as saved projects; every calculator and tool stays free to use.

CORE TOOLS

✓ Ft-in-fraction keyboard with mm, cm, m; big glove-friendly keys
✓ Exact fraction math: 1/16 + 1/32 = 3/32 with zero rounding error; mix metric freely
✓ Length × length = sq ft, × length again = cu ft and board feet
✓ Rounding to 1/2 … 1/64: nearest, up or down; every result as fraction, decimal and mm
✓ Paperless tape you can reuse, copy or share; memory keys M+ M− MR MC
✓ Share any tool's result as plain text
✓ Board feet and lumber cost; nominal to actual lumber sizes
✓ Right triangle / roof pitch: any 2 of rise, run, diagonal, angle
✓ Stairs with code warnings and landings; printable stringer diagram (PNG/PDF)
✓ Square up from sides and diagonals, with a scaled 3-4-5 check

FRAMING AND ROOFS

✓ Rafters: common rafter, birdsmouth and HAP, hip/valley, jack list with step-down; share the diagram (PNG) or a printable cut sheet (PDF)
✓ Irregular hip for two pitches: plan angle, cheek cuts, backing bevel, cut sheet PDF
✓ Enter any slope as 6/12, 50%, 26.6° or 1:2; results show all four
✓ Wall framing: studs, king and jack studs, headers, sills, cripples, plates and sheathing for a wall with doors and windows, with an elevation diagram and layout marks (Pro: more than 2 openings, saved walls, total takeoff)
✓ Equal spacing for balusters, pickets and shelves (4" sphere rule)
✓ Crown molding compound miter and bevel

CUTTING AND ESTIMATING

✓ Cut-list optimizer: fewest boards with kerf, trim allowance, offcut library, PDF cut plan and shopping list
✓ Sheet cut optimizer: plywood and MDF parts on 4×8 or metric sheets with kerf, edge trim, grain lock and edge banding; numbered layout per sheet, yield and waste, share as PNG (Pro: more than 12 part rows, PDF plan, saved projects)
✓ Materials: concrete bags, drywall and sheet goods, paint, flooring or tile, roofing squares, with waste allowance

WORKSHOP EXTRAS

✓ Angle & Pitch: the phone as a level, sent to Rafters or Crown
✓ Arc & radius, polygon frame miters, shelf sag, wood movement
✓ Home-screen widget and app shortcuts; dark mode

ADS AND PRO, PLAINLY

• A banner under the bottom bar (never next to the keypad), and at most every few minutes a full-screen ad when you close a tool. Never on app open or while you type.
• Pro: monthly, 3-month or yearly (free trial for new subscribers), or pay once for lifetime. Prices shown before you buy; cancel any time in Google Play.
• Had the app before 1.5.0? You keep Pro free.

PRIVACY

Ads (Google AdMob, Unity Ads) may use your advertising ID; where the law requires it, you are asked for consent first and can change it in Settings. Anonymous usage stats and crash reports (Firebase) can be switched off in Settings and never include your measurements.

All results are informational. Always verify critical dimensions against the building code in force in your jurisdiction.

In English, Tiếng Việt, Español, Français, हिन्दी, Bahasa Indonesia, 日本語, 한국어, ไทย, العربية, 简体中文 and 繁體中文. Android 6.0 and up.