Framing, Decking & Lumber Calculators
Work out joists, studs, risers, treads and board feet without the arithmetic. Enter your dimensions and get counts, spacings and lumber quantities in imperial or metric.
Choose a calculator
Stair Calculator
Free stair calculator: enter total rise and get equal riser height, tread depth, number of steps, total run and stringer length.
Cubic Yard Calculator
Free cubic yard calculator: convert length, width and depth into cubic yards, cubic feet and cubic metres.
Board Foot Calculator
Free board foot calculator: enter thickness, width, length and quantity to get board feet and cost.
Deck Calculator
Free deck calculator: get decking boards, joists, beams, posts, screws and concrete from your deck dimensions and joist spacing.
Lumber Calculator
Free lumber calculator: get stud counts, top and bottom plates, linear feet and cost for a framed wall from length, height and stud spacing.
Estimating is not designing
These calculators tell you how much material a layout needs. They do not tell you whether the layout is safe. Joist span, beam size, footing depth, ledger attachment and stair geometry are all governed by your local building code, and a deck or stair built to the wrong span table is a genuine hazard rather than an inconvenience. Use these numbers to price and order, and take the structural sizing from your code, a span table, or an engineer — most decks and stairs also need a permit.
Why stair geometry is worth getting exact
Stairs are unforgiving. The total rise must divide into equal risers, and codes typically cap the riser height and set a minimum tread depth, with very little tolerance for variation between steps — an uneven riser at the top of a flight is a classic trip hazard. The calculator divides your measured total rise into a whole number of equal risers and shows the resulting tread depth and total run, so you can check the flight actually fits the space before you cut a stringer.
Frequently asked questions
How many joists do I need for a deck?
Divide the deck length by the joist spacing and add one. Enter your dimensions above and the calculator returns joists, beams, posts and decking boards.
How do I calculate stair risers?
Divide the total rise by your target riser height, round to a whole number, then divide the total rise by that number for the exact riser. The calculator does this and shows the resulting run.
What is a board foot?
A volume of lumber equal to 144 cubic inches — one square foot at one inch thick. Hardwood is usually priced this way.
How many studs do I need for a wall?
Length divided by spacing, plus one, plus extras for corners and openings. Sixteen inch on centre is standard in most residential framing.
Do these calculators size the lumber for me?
No. They count material. Spans, beam sizes and footing depths must come from your local code or an engineer.