PaintCalc: Paint Calculator

PaintCalc works out how much paint a job needs. Enter a room's dimensions, deduct the doors and windows, pick the paint and surface, and it returns the quantity to buy, rounded up to sizes a store actually sells, with a touch-up allowance on top: 10% unless you set it to 0, 5 or 15% in Settings.

QUICK CALCULATE
Already know the wall area? Type it straight in and get the quantity in seconds. Or enter length and width, or the room's perimeter, and PaintCalc does the area for you. Results update as you type.

ROOM BY ROOM
Wall height, length and width, or perimeter. In feet, every length has a feet box and an inches box, so 12 ft 6 in goes in the way you read it off the tape. Deduct standard doors (20 sq ft), large doors (40 sq ft), standard windows (15 sq ft) and large windows (25 sq ft) with simple counters. Add any opening that is not a standard size by its own width and height. Add wall area the room box misses, such as a walk-in closet, the same way. Choose from six paint types: flat/matte, eggshell, satin, semi-gloss, gloss, primer. And six surfaces: smooth drywall, textured drywall, bare wood, previously painted, brick, stucco. Set one, two or three coats. Coverage rates come from published manufacturer specifications, and you can override them with your own figure per room. Each room can carry a short note.

WHAT YOU GET BACK
Gross wall area, the deductions, and net wall area. Exact paint needed, the same figure plus your touch-up allowance, and a plain purchase line: "Buy 3 gal", broken down as the combination of 5-gallon buckets, gallons and quarts that gets you there.

CEILINGS AND TRIM
Turn on ceiling painting per room with its own paint type and coat count. Add baseboard and trim by linear footage and width. Both are calculated separately from the walls.

MULTI-ROOM PROJECTS (Premium)
Add as many rooms as a project needs. Each room keeps its own paint type, surface and coat count. The project summary totals wall area and paint across every room. Press and hold a room to drag it into a new order.

VALIDATE AND LOCK
Once a room is measured, Validate & Lock saves it read-only, so a stray tap cannot change the numbers. Verified rooms turn green on the project, and the room count shows how many are verified. Unlock a room whenever it needs an edit.

COST ESTIMATOR (Premium)
Enter your paint price per gallon or litre, an hourly labour rate and hours, an