← Back to home calculators

Paint Calculator

Estimate paint for rooms, walls, ceilings, doors, windows, coats, primer, waste allowance, and project cost before you buy.

Paint Project Estimate

Activity Accounts planning estimate. This is not a contract, certified estimate, appraisal, or regulatory assessment.

Paint room calculator

Estimate wall and ceiling paint by room size, coats, coverage, openings, primer, waste, and project cost.

What are you trying to do?

Save this project

Save the current mode, every calculator input, and a readable result snapshot in this browser.

Saved on this device
Saved Projects

Room size and paint assumptions

Door and window deductions retain the existing assumptions: 20 square feet per door and 15 square feet per window.

Quantity snapshot

Gross wall area0
Ceiling area0
Door/window deductions0
Paintable area0
Finish-coat coverage area0
Raw paint gallons0
Paint gallons with waste0
Paint gallons to purchase0
Paint material cost$0.00
Primer gallons to purchase0
Primer material cost$0.00
Total paint and primer cost$0.00

Quick estimate

Paint gallons to purchase0
Primer gallons to purchase0
Paint and primer material cost$0.00
Rough modeled project total$0.00
Rough cost per paintable square footNot available
Additional rough project allowances

Optional planning allowances not included in calculated paint and primer material cost.

Need more detail?

Cost estimator

Edit the paint cost per gallon, coverage rate, primer cost, and primer coverage to match the product you plan to buy. The calculator rounds up to whole gallons because paint is normally purchased by the can.

Waste and extra paint

Default 10%. Add extra paint if your walls are textured, patched, dark-colored, unprimed, or if you want leftovers for touch-ups later.

Common paint assumptions

ItemDefault assumption
Door deduction20 sq ft
Window deduction15 sq ft
Paint coverage300–400 sq ft/gallon
Typical coats2 coats
Waste/extra10%

Plain-English guide

The calculator starts with wall area: two times the room length plus width, multiplied by wall height. It subtracts standard door and window areas, optionally adds the ceiling, multiplies by the number of coats, then divides by paint coverage. Primer is estimated separately because primer coverage and cost can differ from wall paint.

Paint calculator FAQ

How many coats of paint do I need?

Two coats is a common default for interior walls. One coat may work for similar colors in good condition, while dark color changes, patched walls, or uneven surfaces may need primer and two finish coats.

Does primer count as a coat?

Primer is usually counted separately from paint coats. It helps seal surfaces, improve adhesion, and cover stains or strong color changes before finish paint.

How much paint do I need for one room?

Measure the room length, width, and wall height, subtract doors and windows, then multiply by coats. This calculator does that math and rounds the gallons up for buying paint.

Should I subtract windows and doors?

Yes, for a closer estimate. This calculator subtracts 20 square feet per door and 15 square feet per window by default.

How much extra paint should I buy?

A 10% extra allowance is a practical starting point. Buy more if walls are textured, patched, dark, unprimed, or if you want touch-up paint later.

Comments

Comments should stay helpful and project-related. Submissions may be filtered or removed if they are spam, abusive, or unsafe. Do not rely on comments as professional advice.

Max 24 characters.
Max 100 characters. No links, HTML, markdown, emojis, or uploads.

No approved comments yet.