Six calculators for the questions that come up before a job starts: how much to buy, how deep it needs to be, and what that will cost. No sign-up, no email, nothing stored — they run entirely in your browser.
Each one shows its method and its sources at the bottom of the page, so you can check the arithmetic instead of trusting it.
Wire size
Conductor size for a branch circuit, checked against both ampacity and voltage drop, with the derating shown step by step. Handles NM-B versus conduit, copper versus aluminum, and the continuous-load and small-conductor rules people usually miss.
Source: NEC Tables 310.16, 310.15, 240.4(D), 240.6(A) 🏠Attic insulation R-value
Pick your state and what is up there now. Returns your climate zone's target R-value, plus the depth and material cost for cellulose, blown fiberglass, batts, mineral wool and closed-cell foam.
Source: DOE/CE-0180, Oak Ridge National Laboratory 🎨Paint quantity
Room size, openings, surface type and coats give gallons for walls, ceiling, trim and primer separately — at realistic spread rates rather than the optimistic number printed on the can.
Method: published spread rates, low end of range 📐Flooring boxes
How many cartons to order once layout and room complexity are accounted for. Straight, diagonal and herringbone allowances, and why running short mid-floor is the expensive mistake.
Method: standard industry waste allowances 🪵Deck materials
Deck boards, joists, hangers and screws from your deck's dimensions, using actual board widths and your chosen gap. Materials only — spans and footings come from your building department.
Method: geometry on actual, not nominal, dimensions 📏Board feet
Hardwood volume and cost from thickness, width, length and quantity — including why a 4/4 board arrives measuring three-quarters of an inch.
Method: T × W × L ÷ 144, on rough dimensionsWhat these will not do. None of them size anything structural. Joist spans, beam sizing, header sizing and footing depth depend on species, grade, span, ground snow load and local code amendments — a wrong number there is a failure, not a wasted trip to the yard. For those, use your building department or the American Wood Council's Prescriptive Residential Wood Deck Construction Guide (DCA 6).
Costs are materials-only estimates with deliberately wide ranges. Installed pricing is usually double to triple, and depends far more on access than on square footage.
Spot a number that looks wrong? Tell us which tool and which figure — get in touch. Corrections get made to the page.