MaterialQuant

Interior Calculator

Measure rooms, doors and windows once. Calculate paint containers, drywall sheets and wallpaper rolls with a consolidated material order.

Start with a room, then switch on the materials you need. Each material can use all rooms or just the rooms you choose. Results stay visible beside the measurements on larger screens.

Measure the rooms once

Walls, ceiling and openings. Every material below reads these.

Length and width of the floor, and the wall height.

Doors & windows entered once — each material decides how to treat them

What are you calculating?

Pick one or several. Each reads the rooms above.

Paint

On by default: an opening has no wall surface to paint. Turning this off adds margin; it does not calculate door or trim paint.

Wall paint

Data sheet 101.02A: 350–400 sq. ft. per gallon at 4 mils wet, 1.4 mils dry.

Two coats is the manufacturers' recommendation — Benjamin Moore: two coats for full color development, two on bare surfaces; previously painted surfaces can take 1 or 2.

Primer

Choose primer from your product's preparation instructions. SuperPaint lists two self-priming coats on drywall or a separate primer followed by two finish coats. Surface condition and color changes can require a different system.

Buying

Gallons are bought at the low end of the manufacturer's coverage range, rounded up to whole containers with the least paint left over.

%

None by default — no manufacturer publishes one.

Prices

Wall paint

One room, three different material requirements

A room is geometry: wall length, height, ceiling area and openings. Paint subtracts openings by default. Drywall keeps them because hanging and cutting can consume the board across an opening. Wallpaper counts full strips rather than subtracting door area. You can change these choices without measuring the room again.

Worked example: bedroom renovation

A 12 × 10 ft bedroom with 8 ft walls has a 44 ft perimeter, 352 ft² of walls and a 120 ft² ceiling. One 3 × 7 ft door and two 3 × 4 ft windows total 45 ft² of openings. That leaves 307 ft² of paintable walls. Two coats at 350 ft² per US gallon need 1.754 gallons: buy two 1-gallon containers if quarts are disabled.

The same room for board and paper

With openings included, walls plus ceiling require 472 ft² of drywall. A 10% planning allowance gives 519.2 ft²: 17 sheets at 4 × 8 ft. Wallpaper at 20.5 in wide needs 26 full-height strips around the 44 ft perimeter. With no repeat and 4 in trim, each strip is 100 in long; a 33 ft bolt supplies three strips. Nine bolts cover the strips, plus the optional spare. These are alternative or staged material applications, not a recommendation to paper and paint every wall.

Multiple rooms and finishes

Add named rooms and choose which ones each module covers. Quantities consolidate within the selected material. Paint walls and ceilings remain separate purchase lines, with primer separate again. Each line assumes the same product and color across its selected rooms. For different colors or wallpaper products, save separate project links; do not combine unlike finishes into one order.

Save an order without an account

Enter an optional project name, then copy the order, print it or copy a share link. A share link carries the project measurements and choices; it takes priority over the browser’s last saved draft. Drafts stay on this browser. Share links are not private storage: avoid personal addresses or sensitive notes.

Questions before you order

Can I measure a nonrectangular room?

Choose Custom room and enter the known wall area, ceiling area or wall length and height. Wallpaper needs wall length and height to plan full strips; wall area alone is insufficient.

Do I need to enter the windows three times?

No. Doors and windows belong to the shared room. Each material applies its own deduction rule. Correcting an opening updates every module that uses that room.

Does the calculator specify a building assembly?

No. It estimates purchases from your measurements and product choices. Board type, fire rating, substrate preparation and installation requirements must come from the project and product instructions.

Product sources and assumptions

Presets describe named products, not every product in that material family. Confirm current label coverage, sizes, availability and preparation instructions. Custom values let you use the product you are buying. Prices are entered by you.

Paint

Drywall

Wallpaper

See methodology and sources for the assumptions behind the rest of your project.

Use the same measurements

Working outside too? Open the Hardscaping Calculator or Landscaping Calculator for those material orders.