Primer and Paint Quantity Planner
Calculate gallons and whole 1-gallon containers for primer and finish paint with their own label coverage and prices. This is not a compatibility endorsement, automatic primer prescription or substitute for checking an actual surface.
Check whether primer is needed before calculating
This calculator does not decide whether a particular coating must use primer: you choose the number of primer coats using the actual substrate, product guidance and preparation plan. Read Primer vs. Paint: When to Use a Separate Coating, then use our Paint Finish Selector to consider sheen and our standard Paint Calculator when only finish paint is needed.
Sherwin-Williams' primer guide distinguishes drywall-sealing, adhesion and stain-blocking primers. Product-specific labels—not a generic brand assumption—set suitability and coverage. The EPA recommends lead-safe renovation precautions when disturbing old paint in pre-1978 homes.
Round primer and finish paint as separate orders
A measured 350-square-foot surface with a 10% allowance becomes 385 square feet per coat. One primer coat at an entered coverage of 300 square feet per gallon needs about 1.28 gallons, so a one-gallon package choice means two whole cans.
Two finish coats at 350 square feet per gallon need 770 ÷ 350 = 2.2 gallons, or three one-gallon cans. At hypothetical prices of $20 for primer and $35 for finish, that order is 2 × $20 + 3 × $35 = $145. Combining the unrounded liquids first would hide that they are different products.
Check before the next step
Confirm whether primer is needed and use each exact label's coverage, coat requirements and available package sizes. Absorbency, repairs and application losses can differ from an entered allowance.