How to use this grout calculator
- Enter the tiled area.
- Enter the tile size and thickness.
- Enter the joint width (1/16–1/8 in for rectified tile, 1/8–1/4 in for most floors).
Example
A 5 × 8 ft backsplash in 3 × 6 inch subway tile, 1/4 inch thick with 1/16 inch joints, needs about 3.4 lb of grout.
What to know before you buy
Types of grout
Sanded cement grout is the standard for joints 1/8 inch and wider. Unsanded grout is for narrow joints and polished stone that sand could scratch. Epoxy grout is waterproof, stain-proof and does not need sealing, but it is more expensive and harder to work with.
Choosing joint width
Rectified tiles with precise edges can use 1/16–1/8 inch joints. Most floor tiles use 1/8–1/4 inch. Handmade and rustic tiles need wider joints to accommodate size variation.
Grout for 100 sq ft (3/8 in thick tile, 10% waste)
| Tile and joint | Grout needed | 10 lb bags |
|---|---|---|
| 12 × 12 in, 1/8 in joint | 8.5 lb | 1 |
| 12 × 12 in, 1/4 in joint | 17 lb | 2 |
| 6 × 6 in, 1/8 in joint | 17 lb | 2 |
| 12 × 24 in, 1/8 in joint | 6.4 lb | 1 |
| 4 × 4 in, 1/16 in joint | 12.7 lb | 2 |
Formula
Grout volume = area × joint width × tile thickness × (1 ÷ tile length + 1 ÷ tile width), plus 10% waste. Cured grout weighs about 1,900 kg/m³ (≈ 119 lb/ft³).
Tips from the pros
- Mix only as much grout as you can use in about 30 minutes.
- Seal cement-based grout after it cures to resist stains.
- Consider epoxy grout for showers and kitchen backsplashes: it is stain-resistant and does not need sealing.
Common mistakes to avoid
- Using sanded grout in joints narrower than 1/8 inch, where the sand does not fit.
- Wiping the tile too early or with a very wet sponge, which pulls grout out of the joints.
Frequently asked questions
Sanded or unsanded grout?
Use unsanded grout for joints narrower than 1/8 inch and sanded grout for 1/8 inch and wider.
How much grout for 100 sq ft of 12×12 tile?
About 8 lb with 3/8 in thick tile and 1/8 in joints.
How much grout for 100 square feet?
Between about 5 and 20 lb depending on tile size and joint width; 12 × 12 in tiles with 1/8 in joints need about 8 lb.
How long does grout take to dry?
Cement grout can usually be walked on after 24 hours and sealed after 48–72 hours; follow the product label.