How much paint do I need — and what will the paint job cost?

Free, no-signup calculators for homeowners, DIYers and small painting contractors planning an interior or exterior paint job — figure out how much paint to buy (wall, ceiling and trim square footage, coats, coverage per gallon, primer, door and window deductions), how much a paint job costs (interior, exterior, per room, whole house, cabinets, per square foot, labor), and how to sanity-check a painter’s quote. Every tool runs on the surfaces you measure and the prices you enter, and shows its formula, a worked example and a reference table.

How much paint do I need?
Paint to buy3 gallons
Net paintable wall area381 sq ft
Gross wall (54 ft × 8 ft)432 sq ft
Openings deducted1 door + 2 window = 51 sq ft
Coats × coverage2 coats at 350 sq ft/gal

Example: a 12 × 15 ft room, 8 ft walls, 2 coats at 350 sq ft/gal, less one door and two windows — about 3 gallons. Round up to whole gallons, and allow extra for texture, porosity and color change.

Planning estimate: this is a planning estimate from the numbers you enter — not a bid or a contract. Paint quantity and price depend on wall texture, porosity, color change, number of coats, prep and patching, trim and ceilings, height and access, and local labor. Get itemized written quotes from licensed, insured painters before you commit.
Measure your actual surfaces and confirm coverage against the paint you buy. Rough or porous surfaces, a big color change and extra coats all use more paint — allow extra for texture, porosity and waste, and round up to whole gallons/quarts. Coverage varies by product and surface; read the can’s stated spread rate.

The paint job, step by step

Measure → quantity & coverage → interior cost → exterior cost → whole house → cabinets & specialty → selection & planning — the whole job in one focused hub, in the order a careful planner works.

  1. 1

    Paint Quantity & Coverage

    Start here: how much paint do I need (paintable area × coats ÷ coverage), wall & room square footage, ceiling paint, primer, paint coverage per gallon, trim/baseboard linear feet, and exterior siding paint — from the surfaces you measure.

  2. 2

    Interior Painting Cost

    Budget the inside: interior painting cost, cost to paint a room, cost to paint the interior of a house, cost per square foot, cost by room type, and interior labor cost — on the prices you enter from your own quotes.

  3. 3

    Exterior Painting Cost

    Budget the outside: exterior house painting cost, cost to paint the outside of a house, cost per square foot, cost by siding type (wood/stucco/brick/vinyl), repaint vs new construction, and a two-story / height-access cost.

  4. 4

    Whole-House & Project Cost

    The whole job & quote check: cost to paint a house, whole-house interior + exterior, average cost by home size, a painter quote checker, a labor cost estimator, and cost to repaint a house.

  5. 5

    Cabinets & Specialty Surfaces

    High-value adjacencies: kitchen cabinet painting & refinishing cost (by door + drawer count), deck & fence painting/staining cost & quantity, trim & door painting cost, and a brick/stucco/concrete masonry reference.

  6. 6

    Paint Selection & Planning

    Choose and plan: a sheen & finish selector, a paint-type-by-surface reference, how to measure for paint (smallest of three), a prep & primer planning reference (with the pre-1978 lead flag), and a coats & drying-time reference.

The paint coverage-by-surface reference

Our own neutral matrix: the labeled paint coverage / spread rate per gallon by paint type & surface — from smooth drywall at ~350–400 sq ft/gal down to unpainted brick at ~100–200 — with a companion number-of-coats-by-scenario chart, one place instead of a dozen single-brand cans. It powers the how-much-paint calculator, the paint-coverage calculator and the primer calculator; see how it’s built in the methodology.

Open the coverage reference →

Built for the whole paint job — and to stay correct forever

PaintingCalcs gathers the calculations homeowners, DIYers and small painting contractors reach for when a room, a house or a set of cabinets gets painted — how much paint a job needs (paintable area = perimeter × height − openings; gallons = ceil(area × coats ÷ coverage); ceiling = length × width), how much an interior, exterior, whole-house, cabinet or specialty job costs, and how to sanity-check a painter’s quote — quantity → coverage → cost → by-surface → selection, in one focused hub, in US units, without signup, with transparent formulas. Every tool shows not just the answer but the underlying formula, a worked example and a reference table.

Because the tools rest on timeless paintable-area geometry (wall area = perimeter × height; net area = gross − openings; ceiling = L × W; gallons = ceil(area × coats ÷ coverage); primer = ceil(area ÷ primer coverage); trim_lf = Σ perimeters × (1 + waste); cost = area × your $/sq ft [or gallons × your $/gallon] + labor + add-ons − discount, ×(1 + contingency); cabinet cost = (doors + drawers) × your $/unit + labor) and stable, labeled conventions (coverage per gallon by paint & surface, primer coverage, coats by scenario, door/window deductions, cost bands), they stay correct with no maintenance — no live material or labor price list, no regional cost index, no product catalog, no contractor directory. Cost tools use the prices you enter from your own quotes and bills; labeled cost bands are only a sanity guide. More at Sources & formulas, Methodology and About.

Estimates, not bids. Every result is a planning estimate from your own prices, or a paint quantity / coverage guide — not a bid, an application procedure, or surface-prep, structural, lead-abatement or code-compliance advice. Get itemized written quotes from licensed, insured painters; measure your actual surfaces and confirm coverage on the paint can; allow extra for texture, porosity, color change and waste; and follow the EPA RRP rule with a certified firm for pre-1978 lead paint.