Paint Calculator – Estimate Wall Paint, Ceiling Paint & Coverage
🎨 Room Dimensions
🎨 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 |
| Textured Paint | 4-6 m² | 150-200 sq ft |
| Berger / Dulux | 10-12 m² | 350-400 sq ft |
📋 Real-World Painting Examples
💡 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.
📐 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.
If you're planning a full home renovation, you may also need our Construction Cost Estimator to calculate total project expenses.
❓ 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.
Is there a paint calculator app?
Yes, this online paint calculator works instantly on mobile and desktop without installation.
"After 10 years of home renovation, I use this calculator on every painting project. No more wasted paint!"
© 2026 MultiTooSite – Free Paint Calculator for Home & Construction Projects. All rights reserved.
This calculator is for estimation purposes only. Always verify measurements and consult paint professionals for specific projects.