TradeCalc

TradeCalc offers about 40 calculators for trades and home improvement, including concrete, board feet, roofing, paint, drywall, tile and decking, plus three cost estimators and worked-example guides. It is aimed at homeowners and tradespeople planning materials, and waste allowances are included.

TradeCalc is free, needs no signup, and runs in the browser. Results are planning estimates, not contractor quotes.