CoverCalc

Free • No signup • Instant

How much paint do I need?

Enter the room, the walls, and the color change. CoverCalc turns it into a full plan — gallons, primer, the shopping list, and what it costs to do it yourself or hire it out.

Use the calculator See how it works
  • Used by DIYers & pros
  • Math you can verify
  • Mobile-friendly
Your room, drawn as you type. Doors, windows and ceiling update with the form.

Paint project planner

Measure in feet. Tell us the room and the wall, and you get gallons, primer, the shopping list, and a cost range — not just a number.

How to measure a room in two minutes

Length and width: measure floor edge to floor edge along two adjacent walls. A phone's measure app or the tape in a kitchen drawer both work. Round to the nearest half foot.

Wall height: most rooms are 8 ft; newer homes are often 9. A standard interior door is 6 ft 8 in tall, so a wall that runs about 16 inches above the door frame is 8 ft.

Openings: count doors and windows on the walls you're painting. A closet door counts. A wide cased opening or patio slider counts as two doors.

Surface: run a hand across the wall. Smooth means you feel nothing. Fine grit like an orange peel is light texture. Ridges and splotches are knockdown.

Estimates only. The coverage on your can wins.

Pick your paint and we use the manufacturer's stated coverage. See the table.

Most interior wall paint says 350–400. We adjust it for your wall surface.

Adds flat ceiling paint at one coat.

How CoverCalc works

  1. 1

    Measure your walls

    Length, width, ceiling height. A tape measure is enough.

  2. 2

    Subtract openings

    We deduct 21 sq ft per door and 15 sq ft per window automatically.

  3. 3

    Choose coats

    Two coats is standard. One if you’re refreshing the same color.

  4. 4

    Buy the right amount

    We round up to whole gallons so you don’t run out mid-wall.

Built for one job, done well

Honest math

Everything is shown — total area, deductions, coats. You can verify it yourself.

No popups, no signup

You came for an answer. You get an answer. That’s the whole product.

Works on your phone

Use it standing in the paint aisle. It’s fast and the buttons are big.

Smart defaults

Pre-filled with realistic values so you can get an estimate in two seconds.

More calculators, same honest math

Each one shows its formula, adds the right waste factor, and ends with a shopping list and a cost range.

Floors & walls

Tile calculator

Tiles, boxes with waste, thinset and grout for any tile size and layout.

 Walls

Wallpaper calculator

Counts strips per roll with the pattern repeat, the way a hanger does.

 Outdoors

Concrete calculator

Cubic yards and bag counts for slabs, footings and post holes.

 For your site

Embed a calculator

Contractors and paint stores: add the planner to your site in one line.

Paint guides

Quick reads that answer the questions every painter Googles.

How much paint for a room?

Standard rooms by size — bedroom, living room, bathroom.

How many coats of paint?

When one coat works, when you need two, and when three.

Paint coverage per gallon

What the cans say vs. what you actually get.

Exterior paint calculator

Siding, trim, and how weather changes coverage.

Cost to paint a room

DIY versus hiring a painter, by room size, assumptions shown.

Coverage by brand

Behr, Sherwin-Williams, Benjamin Moore and more, quoted from the data sheets.

Paint by room size

10×10, 10×12, 12×12, 12×14, 14×16, 15×20 — gallons by ceiling height.

Frequently asked questions

How much paint do I need for one room?

A standard 12x12 ft room with 8 ft ceilings needs about 1.5 gallons of paint for one coat on the walls. Most projects need two coats, so plan for around 3 gallons. Use the calculator for an exact number.

How many square feet does one gallon of paint cover?

One gallon of interior wall paint covers roughly 350 sq ft on a smooth, primed surface. Rough or unprimed surfaces cover less — sometimes 250 sq ft per gallon.

Do I need primer?

Use primer when painting over bare drywall, stained surfaces, dark colors, or glossy finishes. Skip primer when repainting a similar color over existing latex paint in good condition.

Should I subtract doors and windows?

Yes. The calculator subtracts a standard door (21 sq ft) and window (15 sq ft) per count. This keeps your gallon estimate from running over.

Does the calculator include the ceiling?

No — walls only by default. A separate ceiling calculator is on the roadmap.

Ready to buy paint with confidence?

Calculate now