calculators guides

Guides: measuring, buying and planning

Short, sourced answers to the questions that come up before you buy paint, wallpaper or flooring. Every guide points at the calculator that does the arithmetic.

A hardware store aisle with shelves of paint cans, wallpaper rolls and stacked flooring cartons, a cart in front

Articles

A small bedroom seen from the doorway, furniture covered by a drop cloth, walls half painted terracotta

The three places paint math slips: one coat, the top of the range, and rounding earlyOne coat instead of two, the top of a printed range when your wall sits lower, and rounding before the end. On one bedroom those three are worth a gallon, up to a gallon, and a quart.2026-09-09 · Paint calculator

Primer is a separate can: how much one coat takesA typical primer figure is 200 to 300 square feet a gallon, against 350 to 400 for a finish. On one 371.75-square-foot wall that makes one coat of primer the same purchase as two coats of paint.2026-10-13 · Paint calculator
Benjamin Moore paint calculator: four products, two numbersFour data sheets from one maker print two coverage ranges, not one. Which number belongs in a calculator, what that maker’s own calculator has already assumed, and what the gap is worth on one room.2026-10-06 · Paint calculator
Wall square feet to paint cans: the whole table, and where it stepsA read-off table from 100 to 1,000 square feet of wall at four label coverages, two coats and a 10 percent allowance, with the quart-sized steps that decide which side of a boundary you land on.2026-10-03 · Paint calculator
Paint calculator per square foot: which number goes in, and what a square foot takesAt a 350 label, two coats and a 10 percent allowance, a square foot of wall takes 0.80 fluid ounces and that can covers 159 square feet of wall, not 350. Which square footage a paint calculator wants.2026-10-02 · Paint calculator
The wallpaper calculator refused my half-drop. Here is why I let itSame wall, same roll, same repeat. Switch the match to half-drop and the calculator prints "No valid list yet" instead of a roll count. That refusal is the most honest number on the page.2026-10-01 · Wallpaper calculator
Do I subtract the window? The paint math says one quartA 12-by-14 room has 416 square feet of wall. Taking the door and windows off saves a quart at every label. The default 20 and a measured 44.25 buy the same cans; a slider is where measuring pays.2026-09-30 · Paint calculator
Repainting two rooms at once: count coats before cansA 12-by-14 living room and a 10-by-11 bedroom, 675.50 square feet of wall. One coat or two moves the order by 1.75 to 3 gallons; buying together instead of apart moves it by one quart. Coats first.2026-09-29 · Paint calculator
Closet plus hallway: one flooring order or two?A 15-square-foot closet and a 49-square-foot hallway in one plank. Added and bought once they take 2 to 4 cartons; bought separately, two of six cartons cost an extra box.2026-09-27 · Flooring calculator
Painting a 5-by-8 bathroom: the can size beats the labelOn a 5-by-8 bathroom every coverage figure from 250 to 450 square feet a gallon lands on one gallon plus a quart or less. Whether the shop sells quarts decides one can or two.2026-09-26 · Paint calculator
Why a 108-square-foot wall is not two rolls of wallpaperA 12-by-9 foot wall divided by the 65 square feet on the label looks like two rolls. Counted by the strip it is three on two of the three real rolls, and a two-roll pack makes it four.2026-09-25 · Wallpaper calculator
An L-shaped room in laminate: split it in two, then add the waste only onceA 188-square-foot L-shaped floor worked by hand in three real cartons. Counting the same allowance twice costs a box, and the page you buy from may have added 15 percent already.2026-09-24 · Flooring calculator
Your paint can prints a range, not a number. The two ends are different shopping listsA 14-by-16 living room worked at both ends of the coverage ranges four manufacturers actually print. The same room comes to 4 gallons plus 2 quarts at one end and 2 gallons plus 3 quarts at the other.2026-09-24 · Paint calculator
One accent wall, two rolls: the wallpaper count that stays the same when the repeat changesA 10-by-8 foot accent wall in a straight-match paper takes two 24-inch rolls whether the repeat is 8 inches or 19. The strip math by hand, and the three places the count jumps to three.2026-09-22 · Wallpaper calculator
A 12-by-15 ceiling, two coats: one gallon on paper, and why the quart still goes in the cartWorked example for a 180-square-foot ceiling. Ceiling paint labels say 400 to 450 square feet a gallon, which makes two coats fit in one can with 1.3 ounces to spare. The wall-paint number does not.2026-09-18 · Paint calculator
A 12-by-15 living room in vinyl plank: 4 cartons or 11, depending on the boxWorked example for one floor: measuring, the allowance you choose, whole-carton rounding, and why the same room takes 4 or 11 cartons from the same manufacturer.2026-09-10 · Flooring calculator