Calculates wall area, subtracts doors and windows, applies coats and waste, then converts to paint quantity.
Paint Calculator
Estimate paint for room walls or a known paintable area.
Adjust coats, coverage, openings, and extra allowance before you buy.
Calculator units
Interior or exterior walls, rooms, entire houses, or any painting project.
Surface condition, paint type, color change and actual product coverage.
How it works
How this calculation works
Room mode calculates wall area from the room perimeter and wall height, then subtracts doors and windows.
The calculator multiplies the net paintable area by the number of coats, divides by your coverage rate, and applies the extra allowance.
The purchase recommendation rounds upward so the suggested amount does not fall below the calculated requirement.
Assumptions
What this estimate assumes
- Coverage varies by paint, surface texture, primer use, color change, and application method.
- Door and window defaults are starting values only; replace them with your measurements when accuracy matters.
- Extra allowance is editable and is not a universal requirement.
Example
Example: a typical bedroom
For a 12 ft × 10 ft room with 8 ft walls, one door, two 4 ft × 4 ft windows, two coats, 350 sq ft/gal coverage, and 10% extra, RenoQuantix calculates the net wall area first and then converts that requirement into a practical purchase amount.
Practical tips
Before you buy
- Use the coverage printed on the exact paint product you plan to buy.
- Measure unusually large doors or windows instead of relying on defaults.
- If the new color is dramatically lighter or darker, plan for primer or additional coats.
Calculator limits
Use the result as a planning estimate
RenoQuantix turns the measurements and product information you provide into a material estimate. Product specifications, local requirements, installation methods, site conditions, and measurement error can change the final amount you need.
When the project affects structure, safety, code compliance, or regulated work, confirm those requirements separately.
FAQ
Frequently asked questions
Does this calculator include the ceiling?
No. The room mode is intended for walls. Calculate a ceiling separately using its length and width if needed.
Why is the purchase amount higher than the exact amount?
The recommendation includes your selected extra allowance and rounds upward so you are not told to buy less than the calculated need.
Does RenoQuantix know local paint prices?
No. Enter your own store or supplier price if you want an estimated material cost.
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