Free construction & DIY calculators
Plan your materials before you shop. Each calculator shows the math, names its source, and works in imperial or metric.
Deck builders: free quote makerTurn a deck's dimensions into a priced material list and a branded, printable customer quote.- Deck Joist Spacing Calculator
Count the joists a deck needs from its length and your on-center spacing (12, 16 or 24 in), with total lumber length and the leftover gap at the end.
- Deck Footing Concrete Calculator
Work out the concrete volume for round deck footings in cubic feet and yards, and how many 60 lb or 80 lb bags to buy, with a waste allowance.
- Stair Stringer Calculator
Enter the total rise to get the number of steps, riser height, run, and stringer length, checked against the IRC 7¾ in riser and 10 in tread limits.
- Fence Post Concrete Calculator
Find how many fence posts a straight run needs and how many bags of concrete to set them, after subtracting the volume the post itself takes up.
- Baluster Spacing Calculator
Calculate how many balusters fit between two posts so no gap is wider than 4 in, with the exact even gap and center-to-center spacing.
- Deck Material Calculator
Get a full deck material list from length and width: decking boards, joists and joist length, screws, footings and rim board, with waste included.