Paint Needed
Amount of paint required for a wall area.
Formula
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Example
400 ft² ÷ 350 = 1.14 gal
How it works
This formula tells you how much paint you need by dividing the total wall area by the coverage rate of one gallon. It works because coverage is measured in area per gallon, so dividing area by area-per-gallon cancels the units and leaves gallons. The result is usually rounded up, since you cannot buy a fraction of a gallon in many stores and you may need extra for touch-ups or uneven surfaces.
When to use it
Use this when planning a painting job for walls, ceilings, fences, or other flat surfaces and you know the paint’s coverage rate. It is helpful for shopping, budgeting, and making sure you do not run out of paint halfway through.
Worked example, step by step
Step 1: Find the total area to paint: A = 650 ft² Step 2: Find the coverage per gallon: C = 325 ft²/gal Step 3: Divide area by coverage: Gallons = A / C = 650 / 325 Step 4: Calculate: Gallons = 2 Final answer: You need 2 gallons of paint.
Common mistakes to avoid
- Using square feet for area and forgetting that coverage must be in the same area units
- Not rounding up when the result is a fraction, which can leave you short on paint
- Ignoring extra paint needed for a second coat, textured surfaces, or waste
Did You Know?
Always buy a little extra paint for touch-ups.
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