Carpentry and Woodworking Calculators
These calculators answer the questions carpenters and woodworkers ask before cutting: how many board feet a stack of hardwood is and what it costs, how long a rafter must be and where the plumb and seat cuts go, how many studs, plates and headers a wall takes, what a deck needs in boards, joists and screws, how many sheets of drywall a room uses, which miter and bevel angles close a polygon or fit crown molding, and how to space balusters evenly.
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All Carpentry & Woodworking (7)
Board Foot Calculator
Board feet and cost of lumber from thickness, width and lengthRafter Calculator
Rafter length, plumb and seat cuts from span and roof pitchWall Framing Calculator
Studs, plates and headers for a framed wallDeck Calculator
Deck boards, joists, beams and fasteners for a rectangular deckDrywall Calculator
Drywall sheets, screws, tape and joint compound for a roomMiter Angle Calculator
Miter and bevel angles for polygons and crown moldingBaluster Spacing Calculator
Baluster count and even spacing for a railing
Which tool do I need?
Price a stack of rough hardwood
Enter each board's thickness, width and length to get the total board feet and cost.
Cut rafters for a 6/12 roof
Enter the span, pitch and overhang to get the rafter length and the plumb and seat cut angles.
Order materials for a new deck
Enter the deck size, board width and joist spacing to get boards, joists, beams and screws.
Cut crown molding for an outside corner
Enter the wall angle and spring angle to get the miter and bevel settings for a compound saw.
About Carpentry & Woodworking
Inputs follow how the trade measures, in feet and inches with fractions or in millimetres, with nominal and actual lumber sizes kept separate. Waste allowances are editable because they depend on the layout and the material.
Framing spans, guard heights and baluster gaps are governed by building codes such as the IRC. The calculators use common code values as defaults and say so; confirm them with your local building department.
Guides
- How to Calculate Board Feet: Hardwood, Dimension Lumber and MetricThe board foot formula, why a 2x4 counts as 2 x 4, quarter thicknesses like 4/4 and 8/4, NHLA tally rules, waste allowances and converting board feet to cubic metres.
- Rafter Length, Roof Pitch and the Birdsmouth Cut, Worked OutHow run, rise and the slope factor give a common rafter length, the ridge deduction, plumb and seat cuts, how deep a birdsmouth can go, and hip and jack rafters.
- How Many Studs Do I Need? Wall Framing Takeoffs ExplainedLayout counts at 16 and 24 in, why an 8 ft wall uses 92-5/8 in studs, kings, jacks and cripples, corners and intersections, plates, headers and sheathing.
- Estimating a Deck: Boards, Joists, Screws and Span TablesHow to count deck boards from actual width and gap, nest short rows, count joists and fasteners per crossing, and where the IRC R507 span tables come in.
Frequently asked questions
What is a board foot?
A volume of lumber equal to a board 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches. Hardwood is usually priced by the board foot using nominal thickness.
Why is a 2x4 not actually 2 by 4 inches?
The nominal size is the rough-sawn size before drying and planing. A finished 2x4 measures 1½ by 3½ inches, which the framing and deck calculators use for layout.
How far apart can balusters be?
Most US residential codes require that a 4-inch sphere cannot pass between balusters. The baluster spacing calculator finds even spacing that stays under the gap you set.
How much waste should I allow for drywall and decking?
About 10% for drywall and 5 to 10% for straight decking is a common starting point, more for diagonal layouts and rooms with many corners. Each calculator lets you change it.