Your next home project
Deck calculators
Count surface boards, check quantities from a framing plan, add up the board feet of a lumber list, space the railing balusters, and work through stair geometry.
1MeasureMeasure your deckIn the deck board calculator, with a drawing of your numbers.
2Get the list29 deck surface boardsand 1 more item in the example, ready to print.
3What it costs$4,750 typical jobWhat U.S. owners paid for a deck, porch, patio or terrace, and in 8 big metros.
4Compare quotesDeck quote comparisonPut two or three quotes side by side, line by line.
What to buy
Deck board calculator
Count surface boards and fastening points from deck dimensions, board direction and your framing layout.
Example answer: 29 deck surface boardsCalculate your materialsDeck framing quantity calculator
Count joist lines and planned beam or post quantities. Enter dimensions from a design your local authority accepts.
Example answer: 13 joist linesCalculate your materialsDeck stair calculator
Divide the total rise into equal risers and inspect the stair run before discussing the layout with your designer.
Example answer: 6 equal risersCalculate your materialsDeck railing and baluster calculator
Space balusters evenly under the largest allowed gap, and count railing posts, balusters and rail length for each side of the deck.
Example answer: 72 balustersCalculate your materialsBoard foot calculator
Board feet for any mix of lumber: choose the size, the length and how many, and see the total, the linear feet, the actual size of each board and what the load weighs.
Example answer: 208 board feetCalculate your materialsFootings: concrete for post holes
Opens the concrete calculator on post holes: four holes 10 in wide and 3 ft deep. Set your own depth by the frost line in your area.
Example answer: 12 bags of 80 lbCalculate the concreteSize the frame
How far the joists can span, how far apart the posts can stand and how big each footing must be, from the American Wood Council’s deck guide. Your building department has the final say.
Deck joist span calculator
How far each joist size can span at 12, 16 or 24 inches apart, with the overhang.
Deck beam span calculator
How far apart the posts can stand under each beam, for your joist span.
Deck footing calculator
Footing size and thickness under each post, the tallest 6x6 post, and the bags of concrete.
Deck board staggering calculator
Where every board seam falls, on a joist, and the board lengths to buy.
A worked deck: 16 × 12 ft on a ledger
Southern pine, joists 16 inches apart, the beam 1 ft in from the outer edge. Each size comes from the tools above.
- Joists: 2x8 at 16 in reach 11 ft 10 in, more than the 11 ft span; the 1 ft overhang is inside the 2 ft allowed.
- Beam: two 2x10s may span 7 ft 1 in between posts with joists up to 12 ft, so 3 posts 7 ft apart work, with 1 ft past each end post.
- Footings: 24 in round, 10 in thick, under the middle post and 22 in under the two corner posts; about 13 bags of 80 lb concrete for the 3 pads, more if you pour the footings up to the ground or add a concrete stem.
- Boards: boards running along the house are one 16 ft board a row, no seams: 26 rows of 5½ in boards, before your extra.
What will it cost?
What homeowners reported paying to the Census Bureau (American Housing Survey 2023).
Got quotes? Put the work beside the price
Choose the tool that matches your measurements
| Your material or task | Measurements to bring | What you get |
|---|---|---|
| Deck board calculator | Deck length, Deck width | Deck boards by length, fasteners and railing sections |
| Deck framing quantity calculator | Distance across joists (ft), Length of each joist (ft), Joist centers from plan (in) | Joist and beam lumber, post locations and post lengths |
| Deck stair calculator | Finished deck to landing (in), Chosen maximum riser (in), Chosen tread run (in) | Riser height, tread count and total run |
| Deck railing and baluster calculator | Run length along the deck edge, Distance to the stair opening, Stair opening, post center to post center | Balusters, posts and rail length |
| Board foot calculator | Length (ft), How many | Board feet, linear feet, each board’s actual size and the weight |
Before you measure or order
- How many deck boards do I need? Boards, gaps and screws
Divide the deck’s width across the boards by the board face plus its gap to get the rows, multiply by the boards each row needs and add 10% extra. A 5.5-inch board with a 1/8-inch gap covers 5.625 inches.
- How to build a deck: permit, footings, framing and boards
Get the design and permit first, then build the footings and posts, the ledger or a freestanding frame, the beams and joists, the decking with its maker’s gaps and fasteners, and last the stairs and railing, with an inspection at each stage your town asks for.