What it calculates
Estimate primer gallons from surface area and coverage.
Primer Coverage Calculator
Estimate primer gallons from surface area, coats and product coverage.
Planning and estimating aid only. Verify project requirements, manufacturer instructions, adopted codes, permits, and field conditions before performing regulated work.
Painting estimating
How to Use This Calculator
Use the field units shown below, then compare your result with the worked example. If only repaired patches need primer, measure those patches instead of automatically using the entire room area.
How the calculation works
Surface area × primer coats ÷ coverage per gallon, with the entered waste allowance added.
What the result means
New drywall, masonry, stains and porous surfaces can change actual primer consumption.
Plan primer separately from finish paint
For 300 square feet, one coat and an entered coverage of 300 square feet per gallon, the base need is 1 gallon. A 10% allowance gives 1.1 gallons, which the tool rounds to 2 whole gallons for purchase planning.
Contractor tip: If only repaired patches need primer, measure those patches instead of automatically using the entire room area. Check available package sizes after calculating the needed quantity.
Verify the final quantity
Primer coverage depends on the selected product and substrate. New porous surfaces, spot priming and stain-blocking requirements can differ from finish-coat coverage. Read the product instructions rather than reusing a finish-paint assumption.
Good practice: Compare the calculated quantity with plans, specifications, product packaging and current field conditions before purchasing material.