Reference
Grout and Thinset Coverage Tables
How much grout and thinset mortar a tile floor takes, by tile size, joint and trowel, with the manufacturers' figures they are checked against.
Grout by tile and joint
Grout fills the joints between tiles to their full depth, so the amount depends on the joint width, the tile thickness and how much joint there is per square foot, which is more for small tiles. The figures below come from the grout calculator, which works out the joint volume exactly and converts it to dry powder at a density calibrated to Custom Building Products’ published coverage card. They are without any allowance for mixing loss; add 10%.
| Tile | Thickness (in) | Joint (in) | Grout type | lb per 100 sq ft | sq ft per 25 lb bag |
|---|---|---|---|---|---|
| 2 × 2 in mosaic | 1/4 | 1/16 | unsanded | 14.0 | 179 |
| 3 × 6 in subway | 5/16 | 1/16 | unsanded | 8.9 | 280 |
| 4 × 4 in | 5/16 | 1/8 | sanded | 18.8 | 133 |
| 4 × 4 in | 5/16 | 1/4 | sanded | 36.0 | 70 |
| 6 × 6 in | 5/16 | 1/8 | sanded | 12.7 | 196 |
| 6 × 24 in plank | 3/8 | 1/8 | sanded | 9.6 | 260 |
| 12 × 12 in | 3/8 | 1/8 | sanded | 7.8 | 322 |
| 12 × 12 in | 3/8 | 3/16 | sanded | 11.5 | 217 |
| 12 × 24 in | 3/8 | 1/16 | unsanded | 2.7 | 917 |
| 12 × 24 in | 3/8 | 1/8 | sanded | 5.8 | 428 |
| 18 × 18 in | 3/8 | 1/8 | sanded | 5.2 | 481 |
| 24 × 24 in | 3/8 | 1/8 | sanded | 3.9 | 640 |
The calibration point is Custom Building Products’ grout card, which lists about 348 sq ft per 25 lb bag for 12 × 12 × 3/8 in tile with a 1/8 in joint in unsanded grout; sanded grout is slightly denser, which is why the sanded figure for the same tile is 322. Mapei and Laticrete charts agree within about 15%. Third-party calculators that give much lower coverage for this case usually assume a deeper or wider joint.
Thinset by trowel
Thinset coverage depends on the trowel notch, which is chosen by the tile size. The figures are per 50 lb bag on a flat substrate with the trowel held at 45°, without back-buttering.
| Trowel | Typical tile | sq ft per 50 lb bag | Source |
|---|---|---|---|
| 3/16 in V-notch | Mosaics, wall tile under 6 in | about 120 | Typical chart figure |
| 1/4 × 1/4 in square notch | Tile 6 to 12 in | 85 to 95 (90 used) | Custom Building Products charts (VersaBond, MultiSet, CustomBlend) |
| 1/4 × 3/8 in square notch | Tile 12 to 16 in | 60 to 67 (63 used) | The same charts |
| 1/2 × 1/2 in square notch | Large format, 16 in and up | 30 to 50 (40 used) | Schluter, 30 to 40 over DITRA-HEAT; installer calculators 40 to 50 on a slab |
Back-buttering a skim coat on each tile adds 25 to 50%; the thinset calculator adds 30% when it is ticked. A floor that is not flat can double the mortar, because the bed is then doing the leveling; that is a job for the self-leveling compound calculator first. Board on a floor is bedded in its own layer, about 90 sq ft per bag with a 1/4 in notch, which the cement board calculator counts.
Self-leveler
Custom Building Products lists LevelQuik RS at 46 to 48 sq ft per 50 lb bag at 1/8 in and 23 to 24 sq ft at 1/4 in. Coverage halves as the depth doubles. The self-leveling calculator scales from 47 sq ft at 1/8 in to your average depth.
The guide to thinset coverage explains trowel choice and the 80% and 95% coverage rules, and the guide to tile size and grout joint explains why small tiles take so much more grout. The floor tile calculator counts the tiles these figures go with.