Guides
Practical, numbers-first explanations of how material quantities are estimated. Every guide uses the same formulas as the calculators.
How to measure a room for materials
The five numbers that drive every estimate, how to take them, and what to write down for openings.
Estimating drywall for three walls, not four
Why per-wall scope matters and how a 12 × 12 room drops from 19 sheets to 15.
Floor area is not paintable area
The most common material mistake, with the numbers.
Why you buy more than you use
Allowance, package rounding and leftover, explained line by line.
Buying paint for several rooms at once
When to pool a purchase, when to keep rooms separate, and what the rounding difference is.
Drywall sizes and thickness
Which thickness for walls and ceilings, 4×8 vs 4×12 sheets, and how sheet size changes your count.
How much does a gallon of paint cover?
About 350–400 sq ft per coat — why the real number is lower, and how to turn it into cans.
How to calculate square footage for flooring
Measure the floor, add the right waste allowance, and convert to boxes for any product.
Joint compound, tape and screws
Why accessories are not an area calculation, and how to estimate them from your product’s yield.