Paint Calculator

How to use

1. 1Pick units (feet and inches, or meters) and set the global coverage rate, coats, door area, window area, and waste allowance. Defaults match typical interior latex paint.
2. 2Add a room and type its length, width, and ceiling height. Set the door and window counts. Toggle Include ceiling if you are painting it too.
3. 3Use Custom area mode for an accent wall, ceiling-only repaint, fence, or any single measured surface where you already know the square footage.
4. 4Add more rooms with Add room, or use a Quick-fill chip to load a typical room size into the last row.
5. 5Optional: enter a price per gallon or liter and pick a currency for a total cost. Use Copy full report to grab a clean estimate for your shopping list.

About this tool

Paint Calculator turns a list of rooms or surfaces into a paint shopping list: how many gallons or liters you need, the equivalent number of whole 1-gallon or 1-liter cans, and an optional total cost. For each room you type the length, width, and ceiling height and the tool computes the wall area as perimeter times height, optionally adds the ceiling area (length times width), and subtracts a deduction for each door and each window. The deductions default to a standard 3 ft x 7 ft door (21 sq ft) and a 3 ft x 5 ft window (15 sq ft), and both values are configurable in the global settings if your doors or windows are different. The number of coats (default 2) multiplies the paintable area, and the coverage rate (default 350 sq ft per US gallon or 10 sq m per liter, the typical figure published on interior latex paint labels) divides through to get the paint volume. A waste allowance, defaulting to 10 %, adds a buffer for spills, touch-ups, and uneven absorption that real-world painters always need. A custom-surface mode lets you skip the room math and type a single area directly, which is the right input for an accent wall, a fence, a deck, or any single measured surface. Per-room overrides for coats and coverage handle the case where one wall is bare drywall (lower coverage, more coats) while the rest is a repaint. Set a paint price per gallon or liter and pick from eight currencies (USD, EUR, GBP, CAD, AUD, JPY, INR, TRY) to see a total project cost using the with-waste paint volume. Useful for homeowners pricing a repaint, landlords budgeting between tenants, DIYers buying paint for the first time, contractors quoting a small job, and anyone who wants to avoid making a second trip to the paint store mid-coat. The calculator runs entirely in your browser; nothing is uploaded.

Free to use. Works in your browser. No signup, no login.