How much grout for 12x12 tile floor?
5.2 kg of grout for a 12x12 tile floor, at the settings most people start with. Below the calculator are the same numbers for the alternatives you are likely to choose, and what each one does to the total.
Reviewed · Method: measured dimensions, industry coverage rates, rounded up to real package sizes · How the numbers are calculated
Values are pre-filled for this page. Change anything and hit Recalculate.
The answer, and what it is made of
120 sq ft of 12 x 12 tile with a 3 mm joint at 9 mm deep needs 5.2 kg of grout — one of the 10 kg bag. Buy the full bag even if you only need part of it: opened grout takes up moisture from the air and sets lumpy within weeks.
Planning figure for everything on that list: $19 to $45, with $29 as the realistic middle for the products most people actually buy. These are estimates for budgeting, not quotes. Prices move by region and by season, and the middle figure assumes a mid-range product rather than the cheapest thing on the shelf.
Joint width does most of the work here: 5.2 kg at a 1/8 in joint joint becomes 3.5 kg at 1/16 in joint. The joint is a volume, not a line, so doubling its width roughly doubles the grout for the same floor.
What changes if you change one thing
| Change the joint width | You buy |
|---|---|
| 1/8 in joint | 5.2 kg |
| 1/4 in joint, old uneven floor | 10.4 kg |
| 1/16 in joint, rectified tile | 3.5 kg |
Every row is a live calculation, not an estimate. The shaded row is what this page defaults to.
What goes in the cart
| Item | Quantity |
|---|---|
| Grout, 10 kg bag | 1 bag |
| Grout float (rubber face) | 1 |
| Grout sponge, large pore | 2 |
| Sealer, 1 qt (for porous grout) | 1 qt |
| Bucket + mixing paddle | 1 set |
Do not mix the whole bag. Mixed grout has a 20 to 30 minute pot life. Mix in batches sized to what you can float and wipe in that window, or you will be scraping rock out of the joints.
What this size actually changes
Twelve inch tile doubles the joint length per square foot compared with 12x24, so 120 sq ft of 12x12 needs 5.2 kg where the same area of 12x24 needs under 3. The square format is the reason: every tile contributes two joint edges of 12 in each, and the perimeter-to-area ratio is nearly twice as high as a 1:2 rectangle.
Figure. 12x12 tile floor: 12 x 10 ft. Measure the finished surface, not the room walls — the area between skirting or cabinet faces is the area you pay for.
How the quantity is worked out
Grout quantity is driven by the joint, not the floor. Two jobs with the same square footage can need three times the grout if one uses a 1/4 in joint and the other a 1/16 in joint, because the volume of the gap scales with joint width and depth together. That is why grout bags carry a yield chart instead of a single coverage number.
Depth matters as much as width. A 3/8 in deep joint takes twice the grout of a 3/16 in joint at the same width. On a floor with a deep bed, you are filling a channel, not wiping a line. Cementitious grout also shrinks slightly as it cures, so the joint you fill is not quite the joint you end up with.
How to measure this job
For a general floor, measure the largest rectangle the room fits inside and the largest rectangle the room fits around. The difference is the area taken by a chimney breast, a cupboard or an awkward return, and that difference decides whether the waste allowance is 8 or 15 percent.
Then measure the joint length, not just the area, because grout quantity follows the perimeter of every tile. For grout the useful number is tile size times joint width, and floor area only sets the multiplier at the end.
Mistakes that cost real money
Buying grout by square footage instead of by joint volume
A 10 lb bag does not cover a fixed area. It covers a volume. Two floors of the same size can differ by a factor of three depending on joint width and depth, so the bag count has to come from the joint dimensions, never from the room size alone.
Estimating grout from floor area alone
Two 120 sq ft floors with the same joint can differ by a factor of two in grout if one is 12x12 and the other 24x24. The joint length per square foot is what changes, and it doubles when the tile dimension halves.
Buying one bag for a floor that needs half of two
5.2 kg means one 10 kg bag and a lot left over, or two 5 kg bags and almost none. On a small floor it is worth checking whether the supplier sells a 5 kg bag, because an opened 10 kg bag will not keep for the next job.
Grouting the whole floor in one pass
Grout has a 20 to 30 minute window. On 120 sq ft of 12x12 with narrow joints you will get about a third of the way before it starts to set, and grout that sets on the tile face is removed with acid, not a sponge. Work in sections and clean as you go.
Frequently asked questions
How many square feet does a 10 lb bag of grout cover?
There is no single number, because it depends on tile size, joint width and joint depth. A 10 lb bag on 12x24 tile with a 1/8 in joint covers roughly 100 sq ft. The same bag on 3x6 subway tile with the same joint covers far less, because the joint length per square foot is much higher.
How much grout do I need for a floor?
Work it out from tile size, joint width and joint depth, not from floor area. As a rough guide, 12x12 tile with a 3 mm joint uses about 4.3 kg per 100 sq ft, while 24x24 with the same joint uses about 2.2 kg.
How much grout for a 12x12 tile floor?
Roughly 4.3 kg per 100 sq ft with a 3 mm joint at 9 mm deep. A 120 sq ft floor is about 5.2 kg, so one 10 kg bag with some spare. Wider joints scale almost linearly: a 1/4 in joint doubles it.
Can I grout over old grout?
No. New grout will not bond to old grout and the joint will crumble within months. Rake out at least two thirds of the joint depth, or remove it entirely, then grout fresh. On a small floor this is a couple of hours with a grout saw.
What will the materials for this cost?
A planning range of $19 to $45 for everything in the shopping list, with $29 as the realistic middle. That is materials only: it excludes labour, delivery, tool hire and disposal of the old surface. Treat it as a budgeting figure, not a quote.