Paint Calculator

Estimate how many gallons of paint you need. Here is a simple way to think about it — measure your room, and we will help you plan.

Paint math can be tricky. This calculator does the work for you so you can buy with confidence.

Room Length (feet)

Room Width (feet)

Wall Height (feet)

Number of Doors

Number of Windows

Number of Coats

Coverage per Gallon (sq ft)

Before You Paint

✓Check if the wall needs cleaning — dirt and grease affect paint adhesion.
✓Patch holes and fill cracks before painting for a smooth finish.
✓Use primer when changing colors, covering stains, or painting bare surfaces.
✓Check for peeling paint — find and fix the cause before repainting over it.
✓Protect floors and furniture with drop cloths and painter's tape.
✓Ventilate the room — open windows and use a fan to move air out.
✓For older homes (built before 1978): consider lead paint safety before sanding or scraping. Test before you disturb old paint.

Older Home / Lead Paint Caution

Homes built before 1978 may contain lead-based paint. Do not sand, scrape, or disturb old paint surfaces before checking for lead. Lead paint test kits are available at hardware stores. If lead is found, consult a certified lead abatement professional. This is especially important if children or pregnant women are in the home. For peeling paint, water damage, mold, or unknown surface conditions, get a professional assessment before beginning work.

Know When to Call a Pro

Get professional help before painting if:

▸The home was built before 1978 and you need to sand or scrape old paint.
▸There is significant peeling, water damage, mold, or unknown surface contamination.
▸You are unsure whether old paint contains lead.
▸Children or pregnant women live in the home and old paint will be disturbed.

See full safety guide →

Paint Supplies Checklist

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Paint

Primer (if needed)

Rollers

Brushes

Painter's tape

Drop cloth

Paint tray

Stir sticks

Sandpaper / spackle (if needed)

Coverage varies by paint brand, wall texture, color change, primer use, and surface condition. Always check the paint label. This calculator provides estimates only. For older homes, consider lead paint testing before sanding or scraping old surfaces.