Measurement and conversion calculators

These are the tools you reach for before the material tools. Almost every calculator on this site opens by asking for an area or a dimension, and that figure has to come from somewhere — usually a tape measure and a room that is not a neat rectangle.

Rooms rarely cooperate. A chimney breast, a bay, a return into a hallway or an island in the middle all mean the honest area is several shapes added together and one or two taken back out. Treating such a room as a single rectangle can overstate it by a quarter, which on flooring is real money left in the garage.

Measure to the inside faces, in one unit, and write down what you measured rather than a rounded version of it. Small roundings applied shape by shape compound quickly across four of them, and the material calculators add their own waste allowance afterwards — so rounding up as you measure means paying for the same margin twice. Take the raw figure here, then let the material tool decide what to add.