Free Construction Calculators
Quick, transparent calculators with the formula and reference values shown. No signup.
Rebar Weight Calculator
Free rebar weight calculator: pick a bar size (#3 to #18), enter bar count, length and waste, and get total pounds and short tons. Includes the standard rebar weight chart.
Next step: Ironbid
Voltage Drop Calculator
Free voltage drop calculator for electricians: choose conductor size (14 AWG to 4/0), copper or aluminum, single or three phase, amps and one-way length to get volts dropped and percent drop.
Next step: Amperio
Construction Markup vs Margin Calculator
Free construction markup and margin calculator: enter your cost and a markup or a target margin to get the bid price, gross profit and the equivalent percentage, plus a markup-to-margin chart.
Next step: OneEstimate
Construction Retainage Calculator
Free construction retainage calculator: enter contract value, percent complete, retainage rate and previous payments to see work billed to date, retainage held and the net amount due this period.
Next step: OneMake
Real Estate Sales Absorption Calculator
Free sales absorption calculator for developers and home builders: enter total units, units sold and months on sale to get the monthly absorption rate, months to sell out and the pace needed to hit a target date.
Next step: Unami
ZANDYC's Software Picks
One recommended tool per buyer need.
- OneEstimatePick for general construction estimating and biddingBuild your next estimate in OneEstimate
- AmperioPick for electrical estimating for electrical contractorsTry Amperio for your next electrical bid
- IronbidPick for rebar and structural steel estimatingTry Ironbid for your next rebar or steel bid
- UnamiPick for real estate sales CRM for developers and home buildersSee how Unami sells your projects faster
- OneMakePick for running construction projects end-to-end (construction ERP)See how OneMake runs your projects end-to-end