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Carpentry
Calculators
101 free calculators for cut lists, stairs, rafters, crown molding and more — shop math that works on your phone, with nothing to install.
Getting started
- Inch fraction calculatorAdd or subtract two measurements written the way a tape shows them, read to the nearest sixteenth, thirty-second or sixty-fourth.
- Feet-inch construction calculatorA pocket construction calculator on screen: feet, inches and fractions on a keypad, square and cubic footage, metric, and pitch, rise, run and diagonal from any two.
- Board cut calculatorHow many pieces of one length come out of a board of another, with the kerf charged between cuts and the leftover shown.
- Sheet layout calculatorHow many same-size panels fit on a sheet of plywood in a plain grid, turned 90° if that fits more.
- Pilot hole calculatorThe right drill bit for a wood screw, by gauge number and by softwood or hardwood.
- Pocket hole screw calculatorScrew length and thread by material thickness, and how far apart to space the holes along an edge joint.
- Panel glue-up calculatorHow many boards it takes to glue up a target panel width, and how much wider to glue up so the rip lands clean.
- Trim and baseboard calculatorLinear footage of flat trim for a room from its perimeter and its doorways, with a waste allowance.
- Miter angle calculatorThe miter for baseboard, casing or chair rail at any corner angle — flat trim, so there's no bevel to set.
- Circle and arc layoutA trammel arm's length for a full circle, or the radius of a shallow arc from its chord and rise.
- Ellipse and elliptical archWhere the two nails go and how long the string is for the string-and-pencil method, or a table of offsets to plot the curve with a tape.
- Grid enlargement calculatorScale a small pattern up to full size using the classic square-by-square grid method.
Buying material
- Cut list optimizerLay your parts out on a sheet of plywood and get the cuts in order. Accounts for blade kerf and keeps the grain running the right way.
- Board foot calculatorHow much lumber to buy for a finished piece, what it will cost, and what to ask for at the yard.
- Weight calculatorWhat a board or a stack of sheet goods weighs — for shelf brackets, a car boot, or a freight quote.
- Deck and fence takeoffBoards, joists, posts, pickets, screws and bags of concrete, with the gaps between boards properly counted.
- Pergola calculatorPosts, beams, rafters and top slats for a pergola from its footprint and the spacings you choose, evenly laid out and turned into boards to buy.
- Roofing calculatorSquares, bundles, starter strip, ridge cap and underlayment from a building footprint and a pitch.
- Metal roofing calculatorPanels and their cut length from a footprint and a pitch, with ridge cap, eave and rake trim, purlin rows and screws.
- Gutter calculatorFeet of gutter, sections, hangers, end caps, outlets, and how many downspouts and elbows the roof above them needs.
- Pole barn calculatorPosts, trusses, girts and purlins at the spacings you choose, with the roof and wall steel for a post-frame building.
- Siding calculatorSquares and pieces of lap or panel siding for walls and gables less the openings, with starter strip, J-channel and outside corners.
- Stud calculatorField studs at 16" or 24" on centre, corner studs, and the king and jack studs every opening adds.
- Floor joist spansThe 2021 IRC's maximum span for a 2x6 to 2x12 floor joist by species, grade and spacing, and what would reach when yours falls short.
- Insulation calculatorBags of batts for a wall, floor or attic at 16" or 24" on centre, or the depth and bags of blown-in for a target R-value.
- Fastener calculatorScrews or nails for a sheet good on an edge-and-field pattern, with the box count to buy.
- Paint and finish coverageGallons from an area and a coat count, with the cans to buy for brush, roller or spray.
- Square footage calculatorSquare feet and square yards of a floor as rectangles in feet and inches, added and taken away, with a waste allowance on top.
- Carpet calculatorSquare yards of carpet off a 12', 13' 6" or 15' roll, laid out in drops with the seams marked, plus stairs and pad.
- Wallpaper calculatorRolls of wallpaper counted in strips: the cut length with the pattern repeat matched, how many strips each roll gives, and the rolls to buy.
- Door and window casingEvery head, leg and apron cut to its long point from the opening and the reveal, packed into the sticks you buy.
- Drop ceiling grid and tilesTiles, main tees, cross tees, wall angle and hanger wires for a suspended ceiling, with the border tiles balanced on every wall.
- DrywallSheets of 4x8, 4x10 or 4x12 for a room's walls and ceiling, less doors and windows, with the mud, tape and screws to finish them.
- Concrete footings and slabsCubic yards for a run of post footings or a slab, and the bags of ready-mix that buys.
- Concrete block and brickBlocks or bricks for a wall with waste, the bags of mortar at your bag's own yield, and vertical rebar at your spacing.
- Gravel and mulchCubic yards, tons and bags of gravel, crushed stone, sand, topsoil or mulch for a rectangle, circle or triangle at a depth.
- Raised garden bed calculatorBoard courses, a cut list and corner posts for a stacked-board garden bed, and the soil to fill it in cubic feet, cubic yards and bags.
- Paver patioPavers to buy with waste for the pattern, tons of base gravel, bedding sand and feet of edge restraint for a patio.
- Sheathing4x8 sheets of plywood or OSB for wall sheathing, a roof from its footprint and pitch, or a subfloor, with the H-clips for the roof.
- Shed calculatorA full takeoff for a gable shed — floor joists, studs, plates, rafters, plywood sheets and shingle bundles — from its size, wall height and pitch.
- Epoxy calculator for river tablesResin for a river, rectangle or round pour in gallons, quarts and litres, split into part A and B, and how many pours the label's depth allows.
- Caulk and sealantTubes of caulk for a run of joints, from the bead size, with the feet one tube actually lays.
- Tile grout and thinsetPounds of grout from the tile size and joint, and bags of thinset from the trowel notch.
- Retaining wall blocksBlocks, caps, base gravel and drainage stone for a segmental block wall, checked against the IRC's 48-inch limit.
Cutting and joinery
- Crown molding anglesThe miter and bevel for any corner and any spring angle, plus the single setting for cutting it nested.
- Dovetail and box joint templatesSet out the joint, print it at true 1:1 scale, and glue the paper straight onto the board.
- Wood movementHow far a panel expands and shrinks with the seasons, and what that means for the joint holding it.
- Segmented rings and columnsMiter and bevel for any number of sides, flat or flared, and how long each segment has to be.
- Hexagon and octagon calculatorSide length, across flats and across corners from any one of them, for any regular polygon, with the area, the miter and each frame piece's cut lengths.
- 3-4-5 square checkThe diagonal that proves a corner square from any two leg lengths, scaled up for a full building corner.
- Mortise and tenon sizingTenon thickness and shoulder by the rule of thirds, and the length a blind or through mortise allows.
- Picture frame miter cutsCut lengths, long point to long point, for a rectangular mitered frame, and how much molding to buy.
- Cutting board calculatorStrip count, strip lengths and board feet for a long-grain or end-grain board, with the second glue-up's slices and kerfs worked out.
Layout
- Stair stringersDivide the rise into even risers, lay out the notches, and check the result against the code.
- Stair handrailRail length and angle for a straight flight, the plumb and level cuts, and the IRC height, grip and guard checks.
- Wheelchair rampRamp length from the rise at 1:12 or gentler, with the runs, landings and handrails, checked against the ADA Standards.
- Baluster and slat spacingEven gaps across any span, checked against the 4-inch guard rule, with tape-measure marks that don't drift.
- Wainscoting layoutEven picture-frame boxes across a wall, drawn as an elevation with the cut lengths underneath.
- Board and batten calculatorEven batten spacing across an accent wall from the spacing you want, the marks from one corner, the boards to buy, and a true-size spacer to print.
- RaftersCommon, hip and jack rafters for any pitch, with the birdsmouth laid out and the cut angles alongside.
- Gazebo roof calculatorHip rafter length, pitch and cuts for a hexagonal or octagonal gazebo, where the hips land on the king post, and the posts and beams under them.
- Roof pitch calculatorRise and run, x/12, degrees or a rise over a span turned into all the others, with the slope multiplier and the plumb and seat cuts.
- Roof truss calculatorTop chord, bottom chord and web lengths and angles for a king post, queen post or Fink truss — the geometry, not the engineering.
- Flooring calculatorHow many rows, how wide to rip the first one, and where the end joints fall so they never line up.
- Tile calculatorFull tiles across the middle and a sized cut tile at every edge, centred or started from one wall.
- Shelf-pin hole layoutHole count and marks down a cabinet end panel, on the 32mm system or a plain 1" pitch.
- Fence calculator: post spacingPost count and the actual on-centre spacing for any run and maximum span.
- Door and window rough openingThe rough opening from the slab or window unit, its jambs, shims and floor, and where the king and jack studs and your header go around it.
Cabinets and shelves
- Drawer boxesBox sizes and a cut list from the opening, with the slide clearances rounded the way that still fits.
- Shelf sag and spanHow far a shelf bends under books, how far it can span, and what a strip on the front edge buys you.
- Cabinet boxesA carcass cut list from the finished outside dimensions, face-frame or frameless.
- Closet shelvingShelf and rod heights for a single-hang, double-hang or shelf-only closet, with the shelf's sag checked.
- Cabinet hinge count and placementHinge count from door height, and where each one sits down the door.
- Countertop overhang supportWhether an overhang needs corbels or brackets, and how many, by material and run length.
- Countertop calculatorSquare feet of a straight, L or U countertop with the corner counted once, plus island and backsplash, and how many slabs the pieces come out of.
- Bookshelf spacing calculatorHow many shelves fit a bookcase for the books going on it, even marks for each one, and whether the span will sag.
- Dining table size calculatorTable length and width, or diameter, from the seats around it, the room it needs with a walkway, and the seating run for a kitchen island.
- Desk and workbench height calculatorSeated and standing desk, chair seat, monitor and workbench heights from your elbow height or your height, with the sources named.
- Cabinet door size calculatorDoor sizes from the face frame opening for full overlay, partial overlay or inset, single or pair, and the stile, rail and panel cuts for a five-piece door.
- Cabinet face frame calculatorStiles, rails and mullions to cut for any number of openings across and rows down, pocket-screwed or tenoned, and the opening each one leaves.
Hardware and fasteners
- Screw lengthHow long a screw to put through one board into another, and whether the tip comes out the far side.
- Screw and nail holding strengthWhat a screw, nail or lag holds before it pulls out, by species and by how deep the thread goes.
- Nail sizesWhat a 16d actually measures, common against box against finish, and how many come in a pound.
- Tap and clearance drillsThe drill for a machine screw or a threaded insert, and the clearance hole in the piece it passes through.
- Bolt and lag spacingEdge, end and row distances for bolts through a timber, in the multiples of diameter the NDS sets.
- Concrete screw lengthLength and embedment for a concrete screw, the bit that goes with it, and how deep to drill.
- Clamping pressureHow many clamps a glue-up takes to reach the pressure the glue maker asks for, and how far apart.
- Dowels and biscuitsDowel diameter and length by the rule of thirds, which biscuit the stock takes, and how many along the joint.
- Knob and pull placementWhere the bores go for a knob or a pull, in inches or millimetres, centred or set down from the edge.
- Door hinge mortise and placementButt hinge size, count and the five-and-ten layout for a passage door, with the mortise depth.
Around the house
- Picture hanging templateWhere the nail goes for a sawtooth, two D-rings, or wire — printed at true size so the spacing is exact, not eyeballed.
- Wall anchor weight calculatorHow much a plastic anchor, self-drilling anchor, toggle bolt or heavy-duty strap toggle holds in drywall, and how many it takes.
- Floating shelf bracket templateEven bracket spacing inset from the shelf's own ends, printed at true size so the wall marks are exact.
- Curtain rod bracket templateRod length from the window width and overhang, and bracket spacing printed at true size.
- Bathroom hardware mounting templateScrew spacing and mounting height for a towel bar, robe hook or grab bar, with the blocking a grab bar needs.
- TV mount hole spacing templateVESA hole spacing by pattern and mounting height, printed at true size for the column spread.
- House numbers spacing templateCenter an address on a post, fascia board or wall space, with each character's left edge printed at true size.
- Gallery wall layout templateEvery frame's position from one shared reference, with a true-size spacer for the gap between them.
- French cleat mounting templateWall cleat height and screw spacing for a heavy mirror or cabinet, printed at true size.
- Chicken coop size calculatorCoop floor, run, roost, nest boxes and ventilation from the number of birds, on university extension figures you can change, and a coop of whole feet that holds them.
- Firewood cord calculatorHow much of a 128 cubic foot cord a stack is, what a face cord of that log length comes to, and how long a stack holds one cord.
What you get
Rise per step
7 1/8"
Run per step
10 1/2"
Every calculator answers first and explains after — checked against the 2021 IRC where a code applies, with a diagram and cut marks laid out below it. This is the stair calculator's own worked example, live.
Open the stair calculator →Charts
34 printable reference tables
A calculator answers one question about the board in front of you. A chart answers forty at a glance, which is why the good ones end up taped inside a cabinet door.
Crown molding angle chart · Rafter length chart by roof pitch · Roof pitch chart
Guides
13 tool guides
For the question you do not know to ask yet — that crown takes two saw settings rather than one, or that the blade eats a whole piece out of a board. No rankings, no brands.
Circular saw and track saw · Jointer and planer · Table saw
Questions about this site
- Is this actually free?
- Yes, all 101 calculators, every guide and every answer page are free, with no account and nothing metered. So is every chart; the chart pack, a one-time $2.99, is the same tables as one printable document, for the convenience of printing them in one go. The only other thing for sale is a $0.99 print pass that takes an ad off your printouts — nothing you read on the site is ever behind that one, and there is no subscription for any of it.
- Do I need to sign up or install anything?
- No. Every calculator runs in your browser tab; there is no account, no app, and nothing to download. Add the site to your phone's home screen if you want an icon for it, and it opens exactly the same page, faster.
- Are the numbers checked against a building code?
- Where a code applies — stair risers and treads, guard baluster spacing, rafter birdsmouths — the calculator checks the result against the 2021 IRC and says so on the page. Those figures are defaults, not law: codes are amended locally, so the page also says to ring the building department before you cut, not after.
- Do you store my measurements?
- Nothing you type is sent anywhere — there is no server to send it to. A few things are kept in your browser's local storage, on your device: the cuts you have ticked off in the cut list optimizer, any job you saved under a name, the parts themselves when you send a cut list from one calculator to another, a licence key if you bought one, and your answer about ads if you were asked. All of it is readable only by this site and cleared whenever you clear your browser data. The privacy page lists every one of them and what is in it.
- Why do the calculators start with numbers already filled in?
- Each one opens on a real job — a four-drawer cabinet, a 57" deck stair, 38° crown in a square corner — so you see a finished answer before you change anything. Edit any field and the answer below it updates as you type.