Walls & Interior Calculators

Plan interior wall projects with exact measurements instead of guesswork.

Walls are where small layout mistakes show the most. A batten that is a quarter inch off, or a last gap that is narrower than the rest, is easy to spot once the paint is dry. The calculators in this section do the layout math for you: they share leftover space evenly, convert lumber’s nominal sizes to actual sizes and count the boards you need to buy, with a waste allowance for cuts.

Every tool shows its formula and a worked example, so you can check the numbers on paper before you cut. You can enter sizes in feet and inches, use fractions such as 3 1/2, or switch to metric. Results round to the nearest 1/16 in so they match a standard tape measure.

Board and Batten CalculatorEven batten spacing, layout drawing and boards to buy.

Tips for wall projects

Measure each wall at the top, middle and bottom, and use the smallest width. Older walls are rarely perfectly square.
Find and mark the studs before you lay out trim so you know where nails will hold best.
Prime and paint boards before installing them when you can. It is faster than cutting in around every batten.