Paint Calculator
Calculate the perfect amount of paint for your room
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How Our Paint Calculator Works
Planning a painting project? Our free paint calculator takes the guesswork out of estimating how much paint you’ll need for any room. Simply enter your room’s length, width, and height, and get an instant calculation of the paint quantity required.
Our calculator uses a proven formula that considers all four walls of a standard room: 2 × (Length + Width) × Height. This gives you the total surface area that needs to be painted. We then divide this by 400 square feet (the standard coverage area for one gallon of quality paint) and round up to ensure you have enough paint to complete your project.
Why 400 square feet per gallon? This is the industry standard coverage for most interior paints on smooth surfaces. However, textured walls, multiple coats, or lower-quality paints may require additional paint. Our calculator provides a solid baseline estimate to help you save time and money by avoiding over-purchasing or frustrating trips back to the store.
Whether you’re painting a bedroom, living room, office, or any other space, this tool helps both DIY enthusiasts and professional painters plan their projects more effectively. The calculator accounts for standard room configurations and provides results you can trust.
Frequently Asked Questions
Our paint calculator provides estimates that are typically accurate within 10-15% for standard rooms. The calculation is based on industry-standard coverage of 400 square feet per gallon and assumes smooth walls. For textured surfaces, primer application, or multiple coats, you may need 10-20% more paint than estimated.
No, our calculator provides a conservative estimate by including the full wall area without subtracting doors and windows. This approach ensures you have enough paint and accounts for potential waste, touch-ups, and future repairs. Most professionals recommend this method to avoid running short on paint.
Using our calculator can save you $20-100+ per project by preventing over-purchasing. With paint costing $30-80 per gallon, buying just one extra gallon unnecessarily costs significant money. Additionally, you save time and gas by making fewer trips to the store, and you avoid project delays from running out of paint mid-job.
For rooms with vaulted ceilings, multiple angles, or extensive built-ins, use our calculator as a starting point and add 15-25% extra paint. For very textured walls (like popcorn ceilings), consider adding 20-30% more. When in doubt, consult with paint professionals at your local store for complex architectural features.
Yes, it’s wise to buy 5-10% extra paint beyond our calculation for touch-ups and future maintenance. Paint colors can vary between batches, so having extra from the same batch ensures perfect color matching later. Store leftover paint properly in a cool, dry place for up to 5 years.
Our calculator saves hours of manual calculations and reduces project planning time from 30-60 minutes to under 5 minutes. It eliminates guesswork, reduces store trips, prevents work stoppages, and helps you budget accurately upfront. Professional painters report 15-25% time savings on project planning when using digital calculators.
Yes, our calculator works for most paint types including primer, latex, and oil-based paints, as most cover approximately 400 square feet per gallon. However, some specialty paints (like textured or metallic paints) may have different coverage rates. Always check the manufacturer’s coverage specifications on the paint can for the most accurate estimates.