About Proper Estimate
Free calculators for planning and pricing a deck, before anyone buys a board.
What it is
Proper Estimate is an independent website of free calculators for building jobs, starting with decks, made by Hayder Kh. Enter a few measurements and you get the materials to buy and what the job costs. The calculators run in your browser, with no sign-up.
- Deck calculator: the full materials list and cost for any deck size.
- Deck board calculator: how many deck boards to buy, with gaps and waste.
- Deck stair calculator: steps, riser height, total run and stringer length.
- Deck railing calculator: posts and balusters, spaced so every gap stays under 4 in.
- Deck joist span calculator: the joist size for your span, from the IRC table.
- Deck footing calculator: footings and bags of concrete for your deck.
- Deck stain calculator: gallons of stain for the floor, railing and stairs.
- Deck cost calculator: materials and labor cost, compared across three materials.
Where the numbers come from
- Building code. The rules come from the 2021 International Residential Code (IRC), which most US towns adopt: joist spans from Table R507.6, footings from Section R507.3, stairs from Section R311.7, railings from Section R312, design loads from Table R301.5 and permits from Section R105.2. Each page names the section it uses.
- Real lumber sizes. A 2x10 is 1 1/2 × 9 1/4 in, and the math and the drawings use those actual sizes, so the side views are to scale.
- Materials. Boards are counted by whole rows with the gap between them, concrete from what a bag actually makes, and waste is added where cuts make it.
- Prices. Costs use sample 2026 prices that you can change, because prices differ a lot from one town and supplier to the next.
What it isn't
An estimate is for planning and pricing, not a building plan or an engineer's design. Your soil, snow load, local code and design can change the sizes, and your building department decides what's approved.
Mistakes and suggestions
If a number looks wrong or a calculator you need is missing, write to hello@properestimate.com. Every page is checked against the code it cites.