Thinset and Grout Coverage Chart
Bags of thinset and pounds of grout from 25 to 500 square feet, at three tile sizes, plus what the joint width alone does to the grout order.
Thinset coverage is a property of the trowel, not the tile, and the trowel is chosen for the tile. A quarter inch square notch under small tile gets about 85 square feet from a 50 pound bag. Under a 12 inch tile the notch grows and the coverage falls to about 60. Under large format, with a half inch notch and back buttering, it is nearer 40, so the same floor can take twice the mortar purely because the tile got bigger.
Grout is the opposite. It is pure geometry: the joint volume around each tile, times the tile thickness, at about 105 pounds per cubic foot once mixed. Bigger tile means fewer joints and less grout, which is why the 24 by 24 column runs at roughly half the 12 by 12 column on the same floor at the same thickness.
Thinset bags and grout by area and tile size
| Area | 12x12 bags | 12x12 grout, lb | 12x24 bags | 12x24 grout, lb | 24x24 bags | 24x24 grout, lb |
|---|---|---|---|---|---|---|
| 25 sq ft | 1 | 1.4 | 1 | 1.3 | 1 | 0.8 |
| 50 sq ft | 1 | 2.8 | 2 | 2.5 | 2 | 1.7 |
| 75 sq ft | 2 | 4.2 | 3 | 3.8 | 3 | 2.5 |
| 100 sq ft | 2 | 5.6 | 3 | 5.1 | 3 | 3.4 |
| 150 sq ft | 3 | 8.4 | 5 | 7.6 | 5 | 5.1 |
| 200 sq ft | 4 | 11.2 | 6 | 10.1 | 6 | 6.8 |
| 250 sq ft | 5 | 14 | 7 | 12.7 | 7 | 8.5 |
| 300 sq ft | 6 | 16.8 | 9 | 15.2 | 9 | 10.2 |
| 400 sq ft | 8 | 22.4 | 11 | 20.3 | 11 | 13.6 |
| 500 sq ft | 10 | 28 | 14 | 25.3 | 14 | 17 |
Grout for 100 square feet, by joint width
| Joint width | 3x6 grout, lb | 12x12 grout, lb | 12x24 grout, lb | 24x24 grout, lb |
|---|---|---|---|---|
| 1/16 in | 6.7 | 2.8 | 2.5 | 1.7 |
| 1/8 in | 13 | 5.6 | 5.1 | 3.4 |
| 3/16 in | 19.1 | 8.3 | 7.6 | 5.1 |
| 1/4 in | 24.9 | 11 | 10 | 6.7 |
| 3/8 in | 35.7 | 16.3 | 14.8 | 10 |
| 1/2 in | 45.7 | 21.4 | 19.6 | 13.3 |
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The tile calculator takes your own measurements and returns the number for your job, plus the material list as a printable document. Every cell in the table above came out of that same calculator, run at build time.
Thinset bags run out faster than anybody plans for
The most common shortfall on a tile job is mortar, not tile, because the tile was counted and the mortar was guessed. A bag is 50 pounds and it does not go as far as the bag suggests once the notch is the right size for the tile.
Buy one bag over the number in the table. Unopened thinset keeps if it stays dry and off the concrete floor, and half a bag short at four in the afternoon means the row you already spread skins over before you get back.
Sanded or unsanded is decided by the joint, not the tile
Under an eighth of an inch, unsanded, because sand will not pack into a joint that tight and the grout will not consolidate. An eighth and over, sanded, because unsanded grout shrinks and cracks in a wide joint.
The figures here are for sanded grout at about 105 pounds per cubic foot mixed. Unsanded is lighter, so a tight joint on a polished tile takes fewer pounds than the same joint width would suggest here. Check the bag, because manufacturer coverage charts vary more than the arithmetic does.
Mix what you can place, and mix it the same every time
Grout color is a function of water. A batch mixed wetter than the last one dries lighter, and on a floor the two batches meet in the middle of an open room where everybody will see the line. Measure the water rather than pouring by eye.
The same is true of thinset, and the consequence is worse. Mortar mixed too wet loses strength and slumps under a heavy tile, and mortar that has started to set will not be brought back by adding water, whatever it looks like in the bucket.
Questions people ask
How much thinset do I need for 100 square feet?
About two 50 lb bags under 12 inch tile and three under large format. Coverage falls as the tile gets bigger because the trowel notch grows with it, from roughly 85 square feet per bag under small tile down to about 40 under 24 inch and larger.
How much grout for 100 square feet of 12x12 tile?
About 5.6 pounds with an eighth inch joint, which is one 10 lb box. Take the joint to a quarter inch and it more than doubles. Grout is far more sensitive to joint width than to floor area.
How many pounds of grout are in a box?
Ten or twenty five, for nearly all sanded and unsanded grout sold in the United States. Order to the box rather than to the pound, and take the extra box if the number lands close to the line.
Does tile thickness change the grout I need?
Yes, directly. The joint is a channel as deep as the tile is thick, so a 3/8 inch tile takes 20 percent more grout than a 5/16 inch tile across the same joints. That is why the columns above are set at real thicknesses rather than one average.