Paint Coverage Calculator
When starting a painting project—whether it’s refreshing a bedroom, sprucing up your living room, or tackling an outdoor structure—knowing exactly how much paint to buy is essential. Buy too little, and you’ll need to run back to the store mid-project. Buy too much, and you’ve wasted money and storage space. That’s where our Paint Coverage Calculator comes in.
This simple yet powerful tool helps you estimate how many gallons of paint you need based on three key inputs: surface area, paint coverage rate, and number of coats. By using it, you’ll save time, money, and eliminate guesswork.
How to Use the Paint Coverage Calculator (Step-by-Step)
Our calculator is designed to be straightforward for DIYers, homeowners, and professionals alike. Here’s how to use it:
- Enter the Area to Paint (sq ft):
Measure the total square footage of the surface(s) you’re painting. For walls, this means height × width × number of walls. For multiple surfaces, add all the areas together. - Input the Paint Coverage (sq ft per gallon):
The default is set to 350 sq ft per gallon, which is standard for many paints. Check your paint can for specific coverage info, and adjust this value if needed. - Choose the Number of Coats:
Most paint jobs require at least 2 coats for a smooth, lasting finish. Enter the total number of coats you plan to apply. - Click the “Calculate” Button:
Hit Calculate and instantly get the total number of paint gallons you’ll need. - Reset If Needed:
Want to start over or change values? Simply click the Reset button.
Practical Example: Estimating Paint for a Bedroom
Let’s say you’re painting a standard 12×10 foot bedroom with 8-foot ceilings, and you want to paint all four walls.
- Each wall is roughly 8 ft high. Two walls are 12 ft wide, and two are 10 ft wide.
- Total surface area:
(2 × 12 × 8) + (2 × 10 × 8) = 192 + 160 = 352 sq ft - Paint coverage per gallon: 350 sq ft (default)
- Number of coats: 2
Calculation:(352 × 2) ÷ 350 = 2.01 gallons
Result:
You’ll need 2 gallons of paint to complete the job.
Why Accurate Paint Estimation Matters
- Cost Savings: Overestimating leads to unnecessary expenses. Underestimating causes extra trips to the store.
- Time Efficiency: Proper planning ensures you buy everything in one go.
- Consistent Color Match: Paint mixed at different times might vary slightly in shade. Buying all you need upfront keeps the finish consistent.
- Waste Reduction: Prevent leftover paint cans that may never be used again.
Common Use Cases for This Calculator
- Interior Room Painting: Bedrooms, kitchens, living rooms.
- Exterior Home Painting: Siding, fences, garages.
- DIY Projects: Accent walls, murals, cabinets.
- Professional Jobs: Contractors estimating jobs for clients.
- Commercial Spaces: Offices, retail walls, industrial facilities.
15+ Frequently Asked Questions (FAQs)
1. What is the average paint coverage per gallon?
Most paints cover about 350 square feet per gallon on smooth, primed surfaces. However, coverage can vary depending on paint type and surface texture.
2. How do I calculate the square footage of my room?
Multiply height × width for each wall. Add all wall areas together. Subtract any large windows or doors if desired.
3. How many coats of paint do I need?
At least 2 coats is recommended for solid, even coverage. Porous or darker surfaces may require more.
4. Does this calculator account for doors or windows?
No. If you want more precise results, subtract door/window areas manually from your total square footage.
5. Can I use this calculator for ceilings or floors?
Yes! Simply input the square footage of the ceiling or floor area you wish to paint.
6. What if my paint says it covers more/less than 350 sq ft per gallon?
Adjust the coverage input to match your paint’s actual coverage, found on the can or manufacturer’s specs.
7. Is the result rounded up or down?
The calculator rounds up to ensure you don’t run short. It uses Math.ceil() to round to the nearest whole gallon.
8. Does the calculator work on mobile devices?
Yes, the tool is fully responsive and works seamlessly on desktops, tablets, and smartphones.
9. Can this calculator help with primer estimation too?
Absolutely. Use the same method—just input the surface area and the primer’s coverage rate.
10. Is it better to overestimate or underestimate?
Overestimating slightly is better. It ensures color consistency and allows for touch-ups.
11. Do different paint finishes affect coverage?
Yes. Flat/matte paints tend to cover more efficiently than high-gloss finishes, which may require more coats.
12. Will textured walls affect how much paint I need?
Yes. Textured surfaces (like stucco or popcorn ceilings) require more paint—increase your coverage estimate by 10–25%.
13. Can I use this for spray painting projects?
You can, but spray application often uses more paint. Factor in an additional 20–30% in your area calculation.
14. Is paint absorption the same for all surfaces?
No. New drywall, unsealed wood, and masonry surfaces absorb more paint and may need primer + extra coats.
15. Can I use this for exterior house painting?
Yes. Just measure all siding, trim, and surfaces. Remember, exteriors may need weatherproof or thicker coats.
16. Does the number of colors affect paint needed?
No, but using multiple colors might result in extra paint waste depending on wall layout and transitions.
17. What if I buy paint in quarts or 5-gallon buckets?
The tool provides gallons. You can convert gallons to quarts (1 gal = 4 quarts) or buy larger buckets as needed.
18. Should I factor in leftover paint for touch-ups?
Yes. It’s wise to add 10% extra to your total to account for future touch-ups or small errors.
19. Can I save or print the results?
Currently, the tool doesn’t have a built-in print/save feature, but you can screenshot or manually write down the results.
20. Is there a limit to how much area I can enter?
No limit! You can enter any area size, from small art projects to large commercial buildings.