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Grout size calculator
How much grout does your tile need? Enter the tile size, thickness, joint width and area to see the grout per 100 sq ft, the total with your waste allowance, and how many 25 lb bags to buy.
★ CONSTRUCTION · TILE · REFERENCE TABLE #241
Grout Size Chart: Joint Width & Coverage by Tile 2026
13.92 lb of grout — 1 bag (25 lb) for 100 sq ft. A 12×12 tile with a 3/8 in thickness and a 3/16 in joint needs 12.66 lb per 100 sq ft. Enter your tile size, joint width and room size to see your grout.
12×12 tile needs 12.66 lb per 100 sq ft — before waste
How much grout a floor takes depends on how many joints there are, how wide they are and how deep they go. The joint length per square foot is 144 × (length + width) ÷ (length × width) inches — small tiles have far more joints per square foot than big ones — and the grout per square foot is that length times the joint width times the tile thickness times 0.075 lb per cubic inch, the density of cement grout. On the defaults — tile 12×12, thickness 3/8 in, joint 3/16 in, area 100 sq ft, waste 10% — the grout is 12.66 lb per 100 sq ft, the base is 12.66 lb, the total with waste is 13.92 lb and that is 1 bag (25 lb). The table below is theoretical grout before waste — the calculator adds the waste allowance.
| Tile | Size | Thickness | Joint width | Grout type | lb per 100 sq ft |
|---|---|---|---|---|---|
| Mosaic | 2×2 | 1/4" | 1/16" | unsanded | 16.88 |
| Subway | 3×6 | 5/16" | 1/16" | unsanded | 10.55 |
| Wall tile | 4×4 | 1/4" | 1/8" | unsanded | 16.88 |
| Floor tile | 6×6 | 5/16" | 1/8" | sanded | 14.06 |
| Floor tile | 12×12 | 3/8" | 3/16" | sanded | 12.66 |
| Large format | 12×24 | 3/8" | 1/8" | sanded | 6.33 |
| Large tile | 18×18 | 3/8" | 1/4" | sanded | 11.25 |
| Natural stone | 12×12 | 1/2" | 1/4" | sanded | 22.50 |
| Pavers | 12×12 | 1/2" | 1/2" | sanded | 45.00 |
At the defaults — tile 12×12, thickness 3/8 in, joint 3/16 in, area 100 sq ft, waste 10% — the grout per 100 sq ft is 12.66 lb, the base is 12.66 lb, the total is 13.92 lb and the bags are 1. Check the identities: joint length per sq ft = 144 × (L + W) ÷ (L × W); grout per sq ft = joint length × joint width × thickness × 0.075 lb/in³; lb per 100 sq ft = grout per sq ft × 100; base = lb per 100 sq ft ÷ 100 × area; total = base × (1 + waste ÷ 100); bags = ceil(total ÷ 25). Joint-width guidance follows TCNA: 1/16 in is the minimum for rectified tile, 1/8 in is the typical minimum for large format, sanded grout is for joints 1/8 in and wider, unsanded below 1/8 in. Rounding convention: totals are computed from unrounded values, so rounded parts may differ by a cent from their rounded sum.
The worked example, line by line
Setup: tile 12×12, thickness 3/8 in, joint 3/16 in, area 100 sq ft, waste 10%.
Line 1 — the joint length. 144 × (12 + 12) ÷ (12 × 12) = 144 × 24 ÷ 144 = 24 in of joint per sq ft.
Line 2 — the grout per sq ft. 24 in × 0.1875 in × 0.375 in × 0.075 lb/in³ = 0.1266 lb per sq ft.
Line 3 — the grout per 100 sq ft. 0.1266 lb × 100 = 12.66 lb (exact 12.65625).
Line 4 — the base and the total. Base: 12.66 lb ÷ 100 × 100 = 12.66 lb. Total: 12.66 lb × 1.10 = 13.92 lb.
Line 5 — the bags. 13.92 lb ÷ 25 lb = 0.56, rounded up to 1 bag.
Reverse: the area for exactly 25 lb total is 179.57 sq ft (exact 179.5735); at 179 sq ft the total is 24.92 lb, at 180 sq ft it is 25.06 lb. The joint width for 20 lb total is 0.27 in (exact 0.2694); at 0.27 in the total is 20.05 lb, at 0.26 in it is 19.31 lb. The square tile size for 10 lb per 100 sq ft is 15.19 in (exact 15.1875); at 15.19 in it is 10.00 lb per 100 sq ft, at 15 in it is 10.13, at 16 in it is 9.49. The waste for 15 lb total is 18.52% (exact 18.5185%); at 18.52% the total is 15.00 lb, at 18% it is 14.93 lb, at 19% it is 15.06 lb. The thickness for 20 lb total is 0.54 in (exact 0.5387); at 0.54 in the total is 20.05 lb, at 0.53 in it is 19.68 lb.
Every branch, checked
200 sq ft: 12.66 lb per 100 sq ft, base $25.31, total $27.84 — 2 bags (25 lb). At 200 sq ft the base is 25.31 lb and the total is 27.84 lb — 2 bags, because 27.84 lb is more than one 25 lb bag.
500 sq ft: 12.66 lb per 100 sq ft, base $63.28, total $69.61 — 3 bags (25 lb). At 500 sq ft the base is 63.28 lb and the total is 69.61 lb — 3 bags.
1,000 sq ft: 12.66 lb per 100 sq ft, base $126.56, total $139.22 — 6 bags (25 lb). At 1,000 sq ft the base is 126.56 lb and the total is 139.22 lb — 6 bags.
Joint 1/8 in: 8.44 lb per 100 sq ft, base $8.44, total $9.28 — 1 bag (25 lb). A 1/8 in joint needs 8.44 lb per 100 sq ft — a third less than the 3/16 in default — and the total is 9.28 lb, still 1 bag.
Joint 1/4 in: 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb). A 1/4 in joint needs 16.88 lb per 100 sq ft and the total is 18.56 lb — 1 bag, but only just.
24x24 tile: 6.33 lb per 100 sq ft, base $6.33, total $6.96 — 1 bag (25 lb). A 24x24 tile needs only 6.33 lb per 100 sq ft — half the 12x12 figure — because big tiles have far fewer joints per square foot.
Thickness 1/2 in: 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb). A 1/2 in thick tile needs 16.88 lb per 100 sq ft and the total is 18.56 lb — the deeper joint takes a third more grout.
No waste (0%): 12.66 lb per 100 sq ft, base $12.66, total $12.66 — 1 bag (25 lb). With no waste allowance the total is 12.66 lb — exactly the base — and 1 bag.
Waste 25%: 12.66 lb per 100 sq ft, base $12.66, total $15.82 — 1 bag (25 lb). At 25% waste the total is 15.82 lb — 1 bag.
Waste 100%: 12.66 lb per 100 sq ft, base $12.66, total $25.31 — 2 bags (25 lb). At 100% waste the total is 25.31 lb — 2 bags, because doubling the grout pushes past one bag.
Mosaic 2x2: 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb). A 2x2 mosaic with a 1/4 in thickness and a 1/16 in joint needs 16.88 lb per 100 sq ft — the same as a 12x12 floor tile with a 1/4 in joint, because the mosaic's many joints make up for the narrow width.
What the defaults assume
The model assumes cement grout at 0.075 lb per cubic inch, square tiles with uniform joints, and the full tile thickness filled with grout — it does not model epoxy grout (denser, about 0.09 lb per cubic inch), lippage, uneven joints, or the grout lost in the bucket and on the sponge, which is what the waste allowance is for. It assumes the joint width and thickness you enter apply to the whole area. With 0 sq ft the base is 0.00 lb, the total is 0.00 lb and the bags are 0. With a 0 in joint the grout per 100 sq ft is 0.00 lb, the base is 0.00 lb, the total is 0.00 lb and the bags are 0. A tile length or width of 0 is a validation error — there are no joints to measure. At 1,000 sq ft the base is 126.56 lb, the total is 139.22 lb and the bags are 6. Rounding convention: totals are computed from unrounded values, so rounded parts may differ by a cent from their rounded sum; the reverses are nearest-value solutions, and the exact unrounded figures (179.5735, 0.2694, 15.1875, 18.5185%, 0.5387) are stated wherever the rounded figures appear.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Grout per 100 sq ft | joint length × joint width × thickness × 0.075 lb/in³ × 100 | 12.66 lb. |
| Base grout | lb per 100 sq ft ÷ 100 × area | $12.66. |
| Total grout | base × (1 + waste ÷ 100) | $13.92. |
| Bags (25 lb) | ceil(total ÷ 25) | 1. |
| Area for 25 lb total | 25 ÷ (lb per 100 sq ft ÷ 100 × 1.1) | 179.5735 → 179.57 sq ft. |
| Joint width for 20 lb total | 20 ÷ (100 × 24 × 0.375 × 0.075 × 1.1) | 0.2694 in → 0.27 in. |
| Square tile for 10 lb per 100 sq ft | 151.875 ÷ 10 | 15.1875 in → 15.19 in. |
| Waste for 15 lb total | (15 ÷ base − 1) × 100 | 18.5185% → 18.52%. |
| Thickness for 20 lb total | 20 ÷ (100 × 24 × 0.1875 × 0.075 × 1.1) | 0.5387 in → 0.54 in. |
| 200 sq ft | same model | 12.66 lb per 100 sq ft, base $25.31, total $27.84 — 2 bags (25 lb). |
| 500 sq ft | same model | 12.66 lb per 100 sq ft, base $63.28, total $69.61 — 3 bags (25 lb). |
| 1,000 sq ft | same model | 12.66 lb per 100 sq ft, base $126.56, total $139.22 — 6 bags (25 lb). |
| Joint 1/8 in | same model | 8.44 lb per 100 sq ft, base $8.44, total $9.28 — 1 bag (25 lb). |
| Joint 1/4 in | same model | 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb). |
| 24x24 tile | same model | 6.33 lb per 100 sq ft, base $6.33, total $6.96 — 1 bag (25 lb). |
| Thickness 1/2 in | same model | 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb). |
| No waste (0%) | same model | 12.66 lb per 100 sq ft, base $12.66, total $12.66 — 1 bag (25 lb). |
| Waste 25% | same model | 12.66 lb per 100 sq ft, base $12.66, total $15.82 — 1 bag (25 lb). |
| Waste 100% | same model | 12.66 lb per 100 sq ft, base $12.66, total $25.31 — 2 bags (25 lb). |
| Mosaic 2x2 | same model | 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb). |
Who uses this
- The homeowner tiling a 100 sq ft bathroom floor with 12×12 tile: they learn the grout is 12.66 lb per 100 sq ft and 13.92 lb with waste — 1 bag (25 lb) — and they check the 500 sq ft branch (69.61 lb, 3 bags) for the kitchen that comes next.
- The tiler doing a mosaic backsplash: they learn a 2×2 mosaic needs 16.88 lb per 100 sq ft — more than a big floor tile, because of all the joints — and they check the unsanded rule, since the 1/16 in joint takes unsanded grout.
- The contractor pricing large-format tile: they learn a 12×24 tile needs only 6.33 lb per 100 sq ft at a 1/8 in joint — and they check the 24×24 branch (6.33 lb) to see how little grout big tiles take.
- The DIYer laying pavers: they learn a 12×12 paver with a 1/2 in joint needs 45.00 lb per 100 sq ft — and they check the 1,000 sq ft branch (139.22 lb, 6 bags) before ordering.
Accuracy & limitations
The math is exact arithmetic on your six inputs: joint length per sq ft = 144 × (L + W) ÷ (L × W); grout per sq ft = joint length × joint width × thickness × 0.075 lb/in³; lb per 100 sq ft = grout per sq ft × 100; base = lb per 100 sq ft ÷ 100 × area; total = base × (1 + waste ÷ 100); bags = ceil(total ÷ 25). The 4-decimal exact is shown where the rounding matters: the area for exactly 25 lb total is 179.5735 sq ft (shown as 179.57 sq ft); at 179 sq ft the total is 24.92 lb, at 180 sq ft it is 25.06 lb. The joint width for 20 lb total is 0.2694 in (shown as 0.27 in); at 0.27 in the total is 20.05 lb, at 0.26 in it is 19.31 lb. The square tile size for 10 lb per 100 sq ft is 15.1875 in (shown as 15.19 in); at 15.19 in it is 10.00, at 15 in it is 10.13, at 16 in it is 9.49. The waste for 15 lb total is 18.5185% (shown as 18.52%); at 18.52% the total is 15.00 lb, at 18% it is 14.93 lb, at 19% it is 15.06 lb. The thickness for 20 lb total is 0.5387 in (shown as 0.54 in); at 0.54 in the total is 20.05 lb, at 0.53 in it is 19.68 lb. What the model cannot do is measure your actual floor: real joints vary, tiles are not perfectly square, and epoxy grout is denser than cement grout — buy one extra bag for a big job and return it if you do not open it. The table values are theoretical, before waste. For the tile layout, see the tile size chart; for the slab underneath, see the concrete curing time chart; for the sanding between coats, see the sandpaper grit chart; for the paint over it, see the paint coverage chart; for the rebar in the slab, see the rebar size chart. This is a calculator, not a tiling guide.
Cite this calculatorBright Side Kit. “Grout Size Chart: Joint Width & Coverage by Tile 2026” brightoolbox.com, 2026. Method: joint length per sq ft = 144 × (L + W) ÷ (L × W); grout per sq ft = joint length × joint width × thickness × 0.075 lb/in³ (cement-grout density); lb per 100 sq ft = grout per sq ft × 100; base = lb per 100 sq ft ÷ 100 × area; total = base × (1 + waste ÷ 100); bags = ceil(total ÷ 25), 0 when the total is 0. Joint-width guidance follows TCNA: 1/16 in minimum for rectified tile, 1/8 in typical minimum for large format, sanded grout for joints 1/8 in and wider, unsanded below 1/8 in. The table is theoretical grout before waste. Key idea: small tiles need more grout per square foot than big ones — a 2×2 mosaic needs 16.88 lb per 100 sq ft while a 24×24 tile needs only 6.33 lb. Defaults: tile 12×12, thickness 3/8 in, joint 3/16 in, area 100 sq ft, waste 10% → 12.66 lb per 100 sq ft, base $12.66, total $13.92, 1 bag (25 lb). Table: Mosaic 2×2, 1/4 in, 1/16 in joint, unsanded: 16.88 lb/100 sq ft; Subway 3×6, 5/16 in, 1/16 in joint, unsanded: 10.55 lb/100 sq ft; Wall tile 4×4, 1/4 in, 1/8 in joint, unsanded: 16.88 lb/100 sq ft; Floor tile 6×6, 5/16 in, 1/8 in joint, sanded: 14.06 lb/100 sq ft; Floor tile 12×12, 3/8 in, 3/16 in joint, sanded: 12.66 lb/100 sq ft; Large format 12×24, 3/8 in, 1/8 in joint, sanded: 6.33 lb/100 sq ft; Large tile 18×18, 3/8 in, 1/4 in joint, sanded: 11.25 lb/100 sq ft; Natural stone 12×12, 1/2 in, 1/4 in joint, sanded: 22.50 lb/100 sq ft; Pavers 12×12, 1/2 in, 1/2 in joint, sanded: 45.00 lb/100 sq ft. Branches: 200 sq ft → 12.66 lb per 100 sq ft, base $25.31, total $27.84 — 2 bags (25 lb); 500 sq ft → 12.66 lb per 100 sq ft, base $63.28, total $69.61 — 3 bags (25 lb); 1,000 sq ft → 12.66 lb per 100 sq ft, base $126.56, total $139.22 — 6 bags (25 lb); Joint 1/8 in → 8.44 lb per 100 sq ft, base $8.44, total $9.28 — 1 bag (25 lb); Joint 1/4 in → 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb); 24x24 tile → 6.33 lb per 100 sq ft, base $6.33, total $6.96 — 1 bag (25 lb); Thickness 1/2 in → 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb); No waste (0%) → 12.66 lb per 100 sq ft, base $12.66, total $12.66 — 1 bag (25 lb); Waste 25% → 12.66 lb per 100 sq ft, base $12.66, total $15.82 — 1 bag (25 lb); Waste 100% → 12.66 lb per 100 sq ft, base $12.66, total $25.31 — 2 bags (25 lb); Mosaic 2x2 → 16.88 lb per 100 sq ft, base $16.88, total $18.56 — 1 bag (25 lb). Reverses: area for 25 lb total = 179.57 sq ft (exact 179.5735; at 179 sq ft the total is $24.92, at 180 sq ft it is $25.06); joint width for 20 lb total = 0.27 in (exact 0.2694 in; at 0.27 in the total is $20.05, at 0.26 in it is $19.31); square tile for 10 lb per 100 sq ft = 15.19 in (exact 15.1875 in; at 15.19 in it is 10.00, at 15 in it is 10.13, at 16 in it is 9.49); waste for 15 lb total = 18.52% (exact 18.5185%; at 18.52% the total is $15.00, at 18% it is $14.93, at 19% it is $15.06); thickness for 20 lb total = 0.54 in (exact 0.5387 in; at 0.54 in the total is $20.05, at 0.53 in it is $19.68). Edges: 0 sq ft → 12.66 lb per 100 sq ft, base $0.00, total $0.00 — 0 bags (25 lb); 0 in joint → 0.00 lb per 100 sq ft, base $0.00, total $0.00 — 0 bags (25 lb).
Bright Side Kit. "Grout Size Chart: Joint Width & Coverage by Tile 2026" https://brightoolbox.com/grout-size-chart/ Accessed October 25, 2026.Frequently asked questions
How much grout do I need for 100 sq ft of 12x12 tile?
12.66 lb before waste, 13.92 lb with a 10% waste allowance — 1 bag (25 lb). A 12×12 tile with a 3/8 in thickness and a 3/16 in joint needs 12.66 lb per 100 sq ft (exact 12.65625).
How much grout per 100 sq ft for mosaic tile?
16.88 lb per 100 sq ft. A 2×2 mosaic with a 1/4 in thickness and a 1/16 in joint has far more joints per square foot than a big tile — the same as a 12×12 floor tile with a 1/4 in joint.
Do I use sanded or unsanded grout?
Sanded grout for joints 1/8 in and wider, unsanded below 1/8 in. Sanded grout is stronger in wide joints; unsanded grout fits into narrow joints without scratching. The table marks each tile with the right type.
What joint width do I use for large format tile?
1/8 in is the typical minimum for large format, per TCNA guidance. A 12×24 tile at a 1/8 in joint needs 6.33 lb per 100 sq ft. Rectified tile can go as narrow as 1/16 in.
How many bags of grout for 500 sq ft?
3 bags. At 500 sq ft of 12×12 tile the base is 63.28 lb and the total with 10% waste is 69.61 lb — three 25 lb bags. At 1,000 sq ft it is 139.22 lb, 6 bags.
What area gives exactly 25 lb of grout?
179.57 sq ft. At 179 sq ft the total is 24.92 lb, at 180 sq ft it is 25.06 lb — so one 25 lb bag covers about 180 sq ft of 12×12 tile at a 3/16 in joint.