Paint Project Cost & Material Calculator

Estimate paintable area, primer and paint gallons, supplies, optional labor hours, and a realistic planning range before you shop for materials or compare painting quotes.

Project estimator

Paint, primer, and project cost

Estimate material needs from room dimensions or a known paintable area, then add supplies and optional labor planning.

Worked example: paint gallons, primer, labor hours, and planning total

The default room is 12 ft by 12 ft with 8 ft walls, 1 door, and 2 windows. Wall area is 2 x (12 + 12) x 8 = 384 sq ft. Openings are 1 x 21 + 2 x 15 = 51 sq ft.

Paintable area is 384 - 51 = 333 sq ft because the ceiling is not included. With 2 finish coats, 350 sq ft per gallon coverage, and a 10% buffer, raw paint need is 333 x 2 x 1.10 / 350 = 2.093 gal, rounded up to 3 gal.

Primer need is 333 x 1.10 / 300 = 1.221 gal, rounded up to 2 gal. Materials are 3 x $42 + 2 x $28 + $65 = $247.

Labor hours are ceil((333 x 2 / 150) x 10) / 10 = 4.5 h. Labor is 4.5 x $65 = $292.50, so the planning total is $247 + $292.50 = $539.50, displayed as $540.

How this paint calculator estimates wall and ceiling area

For room mode, wall area is 2 x (length + width) x height, minus standard door and window opening allowances, multiplied by repeated rooms. Ceiling area is added only when the ceiling option is checked. Direct mode uses the paintable area you enter.

How to compute paint and primer gallons from room dimensions

Raw paint need is paintable area x finish coats x waste multiplier / paint coverage. Raw primer need is paintable area x waste multiplier / primer coverage when primer is included. Both values are rounded up to whole units to match how paint is usually purchased.

How finish coats and waste buffer affect paint quantity

More coats and a larger waste buffer raise gallons quickly. Texture, strong color changes, patched walls, porous surfaces, and touch-up needs can all justify a larger buffer than a clean repaint over a similar color.

How optional labor assumptions change the planning total

Labor hours are based on paintable area x coats / productivity, rounded to one decimal hour. This is a planning model only; moving furniture, masking, sanding, patching, cleanup, stairs, and access can change real labor.

How to use this estimate before getting painting quotes

Use the result to check material quantities, compare quote assumptions, and ask better questions. Before hiring, confirm prep, repairs, masking, primer, number of coats, ceiling and trim scope, cleanup, timeline, and touch-up support.

FAQ

Why does the calculator subtract door and window area?

Doors and windows usually do not need wall paint. The room method subtracts standard opening allowances so the starting paintable area is closer to a real interior wall project.

Why is primer included by default, and when can I skip it?

Primer is usually helpful for new drywall, patched walls, strong color changes, stains, raw wood, or surfaces with uneven absorption. A simple repaint over a similar color may not need a separate primer coat.

Why are gallon values always rounded up?

Paint and primer are normally bought in whole containers. Rounding up also helps cover touch-ups, roller loss, texture, and small measurement errors.

Why does the total show a range?

The range is a planning band for uncertainty. Real projects can change because of repairs, masking, moving furniture, primer needs, finish quality, ceiling work, and access.

Is this a final contractor quote?

No. It is a planning tool. A contractor quote should still explain prep, repairs, masking, number of coats, materials, cleanup, access, timeline, and warranty terms.

Project path

What to do next

Area check