Fifteen calculators · open source
Calculators that
compute against
your inputs.
A network of single-purpose tools, each built carefully against a published reference — ACI, ADA, NREL, USDA, manufacturer datasheets — and shown with the math, citations, and edge cases visible.
All fifteen
Pick a calculator.
Each tool runs entirely in your browser. No accounts, no ads on the result, no tracking pixels you can see.
Construction & trades
- 01 Concrete Volume Cubic yards, bags, and ready-mix for slabs, footings, and columns.
- 02 Paint Coverage Gallons of paint and primer by room, coats, and surface texture.
- 03 Drywall Sheets Sheets, screws, mud, and tape for any wall and ceiling area.
- 04 Stair Stringer Risers, treads, and stringer length — checked against IRC and IBC.
- 05 Rebar Lap Splice Tension splice length per ACI 318, with citations.
- 06 Tile Waste & Pattern Order quantity by pattern. Herringbone is not 10%.
- 07 ADA Ramp Slope Run, landings, and handrails per ADA 2010 §405.
- 08 Room BTU Load Single-room heating and cooling sizing — Manual J shortcut.
Energy, lawn & outdoors
- 09 Solar Panel Tilt Tilt, azimuth, monthly production, and seasonal-adjust payback by zip.
- 10 Generator Sizing Running and starting watts by appliance → the size to buy.
- 11 Gravel & Mulch Cubic yards, tons, and bags for gravel, mulch, soil, and stone.
- 12 Hive Expansion Timing Add a super, split, feed, or treat — by USDA zone and month.
Why this site exists
Search engines now answer most calculation questions with a snippet pulled from the highest-ranking page. That works until the question depends on the specific inputs in front of you — the rise on this stoop, the climate zone of this room, the brand of additive in this tank. This site exists for those questions.