BuildToolsHub US Construction Calculators

Paint & Coatings

Primer Coverage Calculator

Estimate primer gallons for new drywall or sealed surfaces.

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Educational US estimate only. Not engineering, structural, code, or professional construction advice. Mix designs, codes, and local conditions vary — verify with licensed professionals and your building department.

Estimator methodology

BuildToolsHub takeoffs separate net measured quantities from ordered quantities. Ordered qty = net × condition-based waste, then rounded for plant or package sizes (e.g. ready-mix to the nearest 0.5 yd³).

  • Concrete bags: Quikrete / SAKRETE published yields (80 lb ≈ 0.60 ft³). Ready-mix contingencies follow ASTM C94 purchaser practice.
  • Rebar: CRSI published lb/ft tables; optional lap allowance ≈ 40× bar diameter (confirm with drawings).
  • Roofing: NRCA squares (100 ft²); pitch factor √(1+(rise/12)²); ~3 bundles/square for standard shingles.
  • Aggregates / fill: ASTM C29-style densities; swell/compaction allowances for haul and place volumes.
  • Masonry: BIA / NCMA common unit factors (e.g. ~1.125 CMU/ft² for 8×16 face).

Use the Order tab for a supplier call sheet and the Assumptions panel for the exact factors applied to this run.

Why use Primer Coverage Calculator

Calculate primer gallons from area and primer coverage rates for new drywall or stain blocking.

Some primers cover differently on porous vs sealed substrates—check the label.

How to use

  1. Enter job dimensions. Pick a pour/layout condition to set industry waste %, or choose Custom.
  2. Review Net vs Order on the Summary tab — order the rounded quantity, not net alone.
  3. Open the Order tab for a supplier checklist, then print, export CSV, or share the link.

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About Primer Coverage Calculator

Do I always need primer?

New drywall, stains, and big color shifts often benefit from primer.

Can paint-and-primer replace primer?

Sometimes on previously painted walls; new drywall usually still needs primer.

Coverage vs paint?

Primer coverage can differ—use the primer product rate.

Is this professional engineering advice?

No. Educational estimates only. Verify with a licensed professional and local codes.

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