Paint Calculator
Estimate paint gallons for room walls with coats and waste.
Use decimals when needed. This estimate updates live and is safe to tweak before you buy materials.
Paint Buying Guide
This guide helps you turn your paint calculator result into a cleaner purchase plan. Use it when you want fewer return trips, better waste assumptions, and a more realistic cart.
Step 1: Account for doors and windows
Measure the room's total wall area, but don't forget to subtract about 20 sq ft for each standard door and 15 sq ft for each window so you don't overbuy.
Step 2: Factor in multiple coats
Always plan for at least two coats, especially if you are covering a dark color or painting fresh drywall. One coat is rarely enough for a professional finish.
Step 3: Buy extra for touch-ups
Round up your total to the next full gallon. Having leftover paint of the exact same mixed batch is crucial for future scuff touch-ups.
Recommended for this job
Commonly paired tools and accessories
These are the practical extras people often forget until the last minute, especially when turning a rough estimate into a real purchase list.
Paint roller kitWhy this helps: Good for faster wall coverage once the paint quantity is set.
Drop cloth setWhy this helps: Useful for protecting floors and furniture before paint goes down.
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Paint cost planning rule of thumb
Build your budget in three bands: paint gallons, applicator tools (rollers, brushes, trays), and prep materials (tape, drop cloths, spackle).
Understanding the Math
Formula: The basic formula for Paint Calculator typically involves calculating the total area or volume (Length × Width × Depth) and dividing by the coverage of a single unit or package, then adding a waste factor (usually 10%).
Example: For example, if you have a 10x10 area and your material covers 10 square feet per unit, you need 10 units. With a 10% waste factor, you should purchase 11 units to ensure you don't run short.
Related Calculators
Paint Calculator FAQ
Do I include windows and doors?
For a quick estimate, use full wall area. For precise buying, subtract about 10-15% if you have large openings.
Should I round up paint?
Yes. Buy a little extra for touch-ups and color consistency.
How long does paint take to dry?
Most latex paints dry to the touch in 1-2 hours, but you should wait 4-6 hours before applying a second coat.
What finish should I use?
Flat or matte for ceilings, eggshell or satin for living areas, and semi-gloss for trim and bathrooms.
Need more painting tips?
Read our comprehensive guide on How to Calculate Paint Needs for Any Room, including tips on surface preparation and choosing the right sheen.