Grout Calculator

Pounds of sanded grout and 25 lb bag count for any tile size, joint width and floor area — with a configurable waste factor.

Tile & joint

in
in
in
Typical: ¼″ (6 mm) ceramic / ⅜″ (10 mm) porcelain.
Wider joints need sanded grout; ⅛″ or less can use unsanded.

Area & pricing

ft²
Use net tile area (gross floor minus closet thresholds, fixtures, etc.).
%
15 % standard; 20 % for complex layouts.
$

Calculation results

Bags needed

— bags

Total grout weight

— lb

Grout per tile area

— lb/ft²

Coverage per bag

— ft²

Grout volume is computed geometrically — joints around each tile filled with sanded grout at 110 lb/ft³ density. Manufacturer coverage tables vary slightly; verify against your specific product.

Informational only. Use sanded grout for joints ⅛″ or wider; unsanded grout for joints below ⅛″ and on polished marble or natural stone (sand scratches the surface). Always seal cement-based grout after curing.

How grout quantity is calculated

Grout fills the joints between tiles. The geometric volume of grout per unit of tile area depends on the tile dimensions, joint width and tile thickness.

grout volume per ft² = 144 × (L + W) × joint_w × thickness / (L × W)

The factor 144 converts the per-square-inch result to per-square-foot. The result is in cubic inches; multiply by grout density (~110 lb/ft³) and divide by 1,728 in³/ft³ to get pounds per square foot.

Worked example — 12 × 12 in tile, ⅛″ joint, ¼″ thick, 200 ft² floor

  • Per ft² = 144 × (12 + 12) × 0.125 × 0.25 / (12 × 12) = 0.75 in³/ft²
  • Total grout = 200 × 0.75 = 150 in³ = 0.0868 ft³
  • Weight = 0.0868 × 110 = 9.55 lb
  • With 15 % waste = 10.98 lb
  • 25 lb bags = ⌈ 10.98 / 25 ⌉ = 1 bag

Sanded vs unsanded grout

  • Sanded: joints ⅛″ (3 mm) or wider. Sand prevents shrinkage cracks in wider joints. Use for floor tile, wall tile with wide joints and tumbled stone.
  • Unsanded: joints < ⅛″. No sand to scratch polished surfaces. Use for polished marble, polished travertine, glass tile and very tight modern installations.
  • Epoxy grout: chemical-set, stain-proof, no sealer needed. Higher cost (3-5× cement grout); harder to install. Recommended for kitchens, showers and commercial environments.

Frequently asked questions

How much grout do I need for 100 square feet of tile?
For 12 × 12 tile with ⅛″ joints and ¼″ thickness: about 5.5 lb of grout, plus 15 % waste = 6.3 lb. That fits in a single 10 lb bag with plenty to spare. For 6 × 6 tile with ¼″ joints: about 22 lb — needs a 25 lb bag.
How many bags of grout for 200 sq ft?
Standard 12 × 12 tile with ⅛″ joints: 1 × 25 lb bag (about 11 lb of grout needed including waste). For 6 × 6 with ¼″ joints: 2 × 25 lb bags. Tile size and joint width matter much more than total area.
Is sanded or unsanded grout better?
Use sanded grout for joints ⅛″ and wider — sand prevents shrinkage cracks. Use unsanded for narrower joints and for polished surfaces (marble, glass tile) that sand could scratch. Epoxy grout is best for wet areas if you can afford it.
How thick should grout be?
Grout depth equals the tile thickness. For ¼″ (6 mm) ceramic tile, grout fills the entire ¼″ depth between tiles. For thicker porcelain or stone, the grout depth follows. The calculator multiplies joint width by tile thickness for the joint cross-section.
How much waste should I add?
15 % for standard rectangular layouts with consistent joints. 20 % for diagonal, herringbone or mosaic layouts where joint geometry varies. Always have a small excess on hand for repairs.
Do I need to seal grout?
Yes — cement-based grout is porous and stains easily. Seal 48-72 hours after grouting once cured. Use a penetrating sealer for floors, a topical sealer for walls. Re-seal every 1-2 years in wet areas. Epoxy grout does NOT need sealing.