How Much Grout Do I Need? Pounds per 100 Sq Ft by Tile Size
Grout fills the joints, so the amount depends on how many joints there are (smaller tiles mean more), how wide they are and how deep (the tile's thickness). 100 sq ft of 12 × 12 inch tile with 1/8 inch joints takes about 8.0 lb of sanded grout, while the same area of 2 × 2 mosaic takes about 32 lb. The tile calculator works out tile, boxes and grout together.
Grout per 100 sq ft by tile size and joint width
Sanded grout at about 0.065 lb per cubic inch, with 10% extra. Joint depth is the tile thickness shown.
| Tile | Thickness | 1/16 in joint | 1/8 in joint | 3/16 in joint |
|---|---|---|---|---|
| 2 × 2 in mosaic | 1/4 in | 16.1 lb | 32.2 lb | 48.3 lb |
| 3 × 6 in subway | 5/16 in | 10.1 lb | 20.1 lb | 30.2 lb |
| 4 × 4 in | 1/4 in | 8.0 lb | 16.1 lb | 24.1 lb |
| 6 × 6 in | 5/16 in | 6.7 lb | 13.4 lb | 20.1 lb |
| 12 × 12 in | 3/8 in | 4.0 lb | 8.0 lb | 12.1 lb |
| 12 × 24 in | 3/8 in | 3.0 lb | 6.0 lb | 9.0 lb |
| 24 × 24 in | 3/8 in | 2.0 lb | 4.0 lb | 6.0 lb |
For other areas, scale the number: 50 sq ft takes half, 25 sq ft a quarter. Grout is sold in 10 and 25 lb bags; leftover dry grout keeps for touch-ups if the bag stays sealed.
The formula
grout (lb) ≈ area (sq ft) × 144 × (tile width + tile length) ÷ (tile width × tile length) × joint width × tile thickness × 0.065
All tile and joint sizes are in inches. Add 10% for waste in the bucket and on the float. Premixed urethane and epoxy grouts list coverage by the tub instead; use the chart on the container.
Worked example: shower
- Walls: about 80 sq ft of 3 × 6 subway tile, 5/16 inch thick, 1/16 inch joints: 8.0 lb
- Floor: 15 sq ft of 2 × 2 mosaic, 1/4 inch thick, 1/8 inch joints: 4.8 lb
- Total: about 13 lb. The walls need unsanded grout (joints under 1/8 inch) and the floor sanded, so buy a 10 lb bag of each.
Tips
- Mix small batches. Cement grout starts to stiffen in about 30 minutes; mix what you can spread and clean in that time.
- Buy all the grout at once from the same lot, so the color matches.
- Seal cement grout after it cures (usually 48 to 72 hours) in showers and kitchens.
Frequently asked questions
How much grout do I need for 100 sq ft?
It depends mostly on tile size. 12 × 12 tile with 1/8 inch joints takes about 8.0 lb, so one 10 lb bag. Small mosaic tile takes several times more: about 32 lb for 2 × 2 inch mosaic.
How much grout per square foot?
About 0.08 lb per sq ft for 12 × 12 tile with 1/8 inch joints, and around 0.10 lb for 3 × 6 subway tile with 1/16 inch joints.
How much grout do I need for a shower?
A typical 3 × 5 ft tub surround or shower with about 80 sq ft of 3 × 6 subway tile on the walls and a 2 × 2 mosaic floor takes about 13 lb of grout: unsanded for the narrow wall joints and sanded for the floor, so a 10 lb bag of each.
Should I use sanded or unsanded grout?
Sanded grout for joints 1/8 inch and wider, and for floors. Unsanded grout for joints narrower than 1/8 inch and for polished stone or glass tile that sand could scratch.