Construction Calculators
Free tools for concrete, stairs, drywall, rebar, fencing, decks, gravel, paint, roofing, tiles and more. Instant results — no signup needed.
Construction projects live and die by accurate material estimates. Order too little and the job stalls while you wait for a second delivery; order too much and you're left with surplus that costs money and space. These calculators eliminate the guesswork by working through the same formulas used by contractors, builders, and licensed estimators.
What these tools cover
The concrete calculator handles slabs, columns, and walls, then converts cubic yards to bag counts for DIYers. The stair calculator checks your rise and run against IRC code limits so you don't fail inspection. The rebar calculator gives you bar count, linear footage, and weight from slab dimensions and spacing. Roofing, drywall, fencing, gravel, paint — each tool includes reference tables and a worked explanation so you understand the number, not just read it.
How to get accurate results
Measure twice before you enter anything. All area-based tools (drywall, tile, paint, roofing) let you add a waste factor — use 10% for straightforward rectangular rooms and 15–20% for rooms with lots of cuts or diagonal patterns. For concrete, round up to the next quarter cubic yard and always account for the site's actual depth, not a nominal depth.
All calculations follow current IRC and industry standards. If a code table has been updated or you spot an error, let us know.
Construction Guides & References
Deeper reading and reference material for the calculators above. Each guide cites ACI 318, IRC 2024 or the relevant industry standard, and links back to the calculator that does the math.