Paint Calculator | Free Paint Coverage Calculator

🎨 Room Dimensions

Length

Width

Height

Unit

Number of Coats

Paint Coverage

Include Ceiling (Length × Width)

Subtract Standard Door (20 sq ft / 1.86 m²)

Subtract Standard Window (15 sq ft / 1.4 m²)

Nasir Badar

Construction Estimator | 10+ Years Experience | 500+ Projects Estimated

"I've personally estimated paint quantities for over 300 residential and commercial painting projects. This calculator uses the same formulas I use on job sites — verified against actual paint consumption."

✓ Certified Painting Contractor | ✓ EPA Lead-Safe Certified | ✓ 10+ Years Experience

🎨 Let me save you from a common painting mistake...

I learned this lesson the hard way. My first DIY painting project, I bought paint based on the room dimensions. I didn't account for doors, windows, or the fact that dark colors need more coats. I ended up with 2 extra gallons of paint I couldn't return. That mistake cost me $80.

That's when I learned: paint estimation isn't just length × width × height. Here's what most people get wrong:

Doors and windows subtract 15-20% of wall area — A standard door is 20 sq ft, a window is 15 sq ft
Dark colors need more coats — Reds and blues often need 3 coats instead of 2
Different surfaces absorb differently — Drywall absorbs more than previously painted surfaces
Ceilings need separate calculation — Don't forget to include ceiling paint in your estimate

This calculator handles all of it — wall area, door/window subtraction, multiple coats, and coverage rates. Enter your room dimensions, get exact liters and gallons. No more wasted paint or last-minute trips to the store.

📖 How to Use This Paint Calculator

Measure your room — Length, width, and height in feet or meters
Enter dimensions — Input measurements in the calculator fields
Select number of coats — 2 coats is standard for most colors
Choose paint coverage — Check your paint can for coverage per liter/gallon
Select options — Include ceiling, subtract doors/windows as needed
Click calculate — Get wall area and paint required in liters and gallons

💡 Pro tip: Always buy 10-15% extra paint for touch-ups and future repairs. Store leftovers in a sealed container.

📊 Paint Coverage Reference Guide

Paint Brand/Type	Coverage per Liter	Coverage per Gallon
Standard Latex	10-12 m²	350-400 sq ft
Premium Paint	12-14 m²	400-500 sq ft
Primer	8-10 m²	300-350 sq ft

📋 Real-World Painting Examples

🏠 Small Bedroom (10'×10'×8')

Wall area: 320 sq ft → 2 coats → 640 sq ft

→ 1.6 gallons → 6.1 liters

🏢 Living Room (15'×12'×8')

Wall area: 432 sq ft → 2 coats → 864 sq ft

→ 2.2 gallons → 8.3 liters

⚠️ My Costly Mistake

Forgot to subtract doors and windows on 400 sq ft wall

→ 0.5 gallons extra → $25 wasted paint

💡 5 Paint Estimation Tips I Wish I Knew

Buy 10-15% extra paint. Touch-ups, mistakes, and future repairs need matching paint from the same batch.
Subtract doors and windows. A standard door is 20 sq ft, a window is 15 sq ft. That's 35 sq ft less paint needed per door/window.
Don't forget the ceiling. Ceilings need paint too. Calculate ceiling area separately (length × width).
Check your paint can's coverage. Different brands have different coverage rates. Always verify before buying.
Store paint properly. Seal the can tightly and store upside down to prevent air from drying out the paint. Keeps for years.

⚠️ IMPORTANT NOTE: This calculator provides estimates based on standard coverage rates. Actual paint needed varies by surface porosity, application method (roller vs spray), and color intensity. Always buy 10-15% extra and test a small area first.

📐 How This Paint Calculator Works

The calculator estimates total wall area using room dimensions, subtracts doors and windows if selected, adds ceiling area if selected, multiplies by the number of coats, and divides by paint coverage to calculate how much paint is required.

The Formula: Paint = (Wall Area + Ceiling Area - Openings) × Coats ÷ Coverage

For paving and road projects, you can also use our Asphalt Calculator to estimate asphalt tonnage and cost.

❓ Frequently Asked Questions

What is a paint calculator?

A paint calculator helps estimate how much paint is required based on wall area, number of coats, and paint coverage per litre.

How does a paint calculator work in square feet?

A paint calculator in square feet multiplies wall width and height to get total area, then divides it by paint coverage per gallon to estimate required paint.

What is the paint calculation formula?

The basic paint calculation formula is: Required Paint = Total Area ÷ Coverage per unit × Number of coats

How much area does 1 gallon of paint cover?

One gallon of standard latex paint typically covers 350-400 square feet for one coat. Premium paints cover 400-500 square feet per gallon.

How much area does 20 litre paint cover?

A 20 litre paint coverage area is usually between 200–280 square meters for one coat, depending on paint quality and surface type.

"After 10 years of painting and construction estimation, I use this calculator on every project. It's saved my clients thousands in wasted paint."

— Nasir Badar, Founder of MultiTooSite

10+ years of construction estimation experience | 500+ projects estimated | EPA Lead-Safe Certified

Paint Calculator – Estimate Wall Paint, Ceiling Paint & Coverage