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: Measure twice
Take two independent measurements and use the larger value when they differ. That single decision prevents most material shortages.
Step 2: Set realistic waste
Simple layouts use lower waste, while angled cuts and pattern matching push waste higher. Do not force one waste value for every room.
Step 3: Buy by package unit
Suppliers sell by boxes, bundles, or rolls. Convert your estimate to purchase units and round up once at checkout.
Cost planning rule of thumb
Build your budget in three bands: material-only, material+consumables, and full project with tool contingency. This keeps expectations realistic before you buy.
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.
Disclosure: these may be affiliate links.
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.