How much area does one gallon cover?

A standard gallon of paint typically covers about 350 to 400 square feet (approx. 32-37 square meters) for a single coat.

Usually, yes. Unless you are painting over a very similar light color with a high-quality primer-and-paint in one, two coats ensure durability and true color depth.

What about the ceiling?

This calculator is primarily for walls. If you are painting the ceiling, measure its length and width separately (Length x Width = Area) and divide by 350 to get gallons.

Paint Calculator | Calculate Paint for Walls & Rooms | Finmato

Paint Smarter, Not Harder

There are two tragedies in DIY painting: running out of paint when you have one wall left, or buying three extra gallons that sit in your garage until they dry out. Both are expensive and annoying.

Our Paint Calculator takes the guesswork out of the equation. By accounting for wall size and specific exclusions like windows and doors, we give you a precise estimate so you can buy exactly what you need.

How Measurement Works

To get a perfect estimate, you need to think in terms of "Net Wall Area".

1. Total Surface Area

This is simply the perimeter of the room multiplied by the ceiling height.
(Length + Width + Length + Width) × Height

2. Deductions

You don't paint doors (usually roughly 21 sq ft) or windows (roughly 15 sq ft). We subtract these from your total to save you money.

3. Coverage Rate

Manufacturers rate paint at ~350-400 sq ft per gallon. Textured walls (stucco, brick) soak up more paint, effectively lowering this coverage rate to 250-300 sq ft.

4. Coats

Going from dark to light? You need 2 coats minimum. Maybe 3. Our calculator lets you assume standard 2-coat coverage.

Bedroom Refresh

A standard 12x12 bedroom with 8ft ceilings usually takes about 2 gallons for two coats. Check based on your specific window count.

Accent Walls

Just painting one wall? Enter the length of that single wall to see if a quart will suffice instead of a gallon.

Whole House

Combine estimates room-by-room to create a master shopping list for your contractor or Home Depot run.

Frequently Asked Questions

What about trim and baseboards?

Trim uses different paint (semi-gloss vs eggshell/matte for walls). You should calculate trim separately by measuring the linear footage.

Should I buy extra?

Yes. Pros recommend buying 10% more than calculated for touch-ups, spills, or uneven textured spots that absorb more paint.

Does paint color matter for quantity?

Indirectly. Dark colors like navy blue or red have poor "hiding" power and often require a tinted primer plus 2-3 coats to look solid, increasing the volume needed.

Estimation Only

This tool provides an estimate. Actual usage varies based on wall texture, paint quality, and application method (sprayer vs roller).

Privacy

We do not collect data on your room dimensions or renovation plans. Everything runs locally in your browser.

Paint Calculator