Grout Calculator
Grout depends on joint volume, not just area. Small tiles, wide joints and thick tiles all push the number up quickly.
How this calculator works
- Joint length per sq ft = 144 × (tile length + tile width) ÷ (tile length × tile width) inches.
- Joint volume = joint length × joint width × tile thickness (grout fills the joint to the tile surface).
- Pounds = volume × 0.0672 lb per cubic inch (a cured density of about 1.86 g/cm³), plus 10% for mixing and cleanup loss. Manufacturer charts vary by product, so compare with the chart on your bag.
Grout questions
Sanded or unsanded grout?
Most manufacturers (and the TCNA Handbook) call for unsanded grout in joints under 1/8 inch and sanded grout for 1/8 inch and wider. Polished marble and glass can scratch, so check the tile maker’s guidance.
Why do mosaics need so much grout?
A 2×2 mosaic has six times the joint length per square foot of a 12×12 tile. The joint volume, and the grout, rises to match.
How long does a bag last once mixed?
Cement grout is usually workable for 30–60 minutes, less in heat. Mix only what you can grout and clean in that window.