Free grout calculator. Enter tile size, joint width, and area to find how much grout you need in pounds and kilograms, bags to buy, and the total cost.
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This calculator estimates grout from the geometry of your tile layout. Grout fills the joints between tiles, so the amount you need depends on four things: the tile size, the joint width, the tile thickness (which sets the joint depth), and the total tiled area. Smaller tiles create more joints per square foot, and wider or deeper joints hold more grout, so a mosaic floor can easily need three to five times the grout of a large-format floor over the same area. Internally, every measurement is converted to millimeters and coverage is computed with the industry-standard formula: coverage = 1.6 × (tile_length + tile_width) × tile_thickness × joint_width / (tile_length × tile_width), giving kilograms of grout per square meter (1.6 is the density of cement grout in kg per liter). That figure is multiplied by your area and a waste allowance, then converted to pounds as well. The total is divided by your bag weight and rounded up to whole bags, since grout is sold in sealed bags, and multiplied by the price per bag for the cost estimate. The worked example on this page uses a 100 sq ft floor with 12x12 in tiles, 1/4 in thick, and 1/8 in joints: about 0.21 kg per m2, roughly 2.16 kg (4.77 lb) with 10% waste, which fits in a single 25 lb bag. Enter your own numbers for the exact figure, and always check the coverage printed on your grout bag, since products vary.
A grout calculator tells you how much grout to buy for a tile project. You enter the tile size, the joint width, the tile thickness, and the total tiled area, and it returns the grout needed in pounds and kilograms, the number of bags to buy (rounded up), and an estimated cost. It removes the most common tiling mistake after under-ordering tiles: running out of grout halfway through the job, when a second batch can dry a slightly different shade.
Start by picking your currency, the area unit (square feet or square meters), and the tile size unit (inches or centimeters). Enter the tiled area, then the tile length, width, and thickness from the box, plus your planned grout joint width. Set the waste allowance (10% is standard for mixing loss and spillage), then enter the grout bag weight and price per bag from the store shelf. The calculator instantly shows the grout needed in pounds and kilograms, bags to buy, and the estimated cost.
All dimensions are converted to millimeters first, so imperial and metric inputs mix freely. Step one: coverage_kg_per_m2 = 1.6 × (tile_length + tile_width) × tile_thickness × joint_width / (tile_length × tile_width), with every dimension in millimeters. This is the industry-standard coverage formula: joints around each tile form the volume, and 1.6 is the density of cement grout in kg per liter. Step two: total_grout = coverage × area × (1 + waste_percent/100). Step three: bags = ceil(total_grout / bag_weight), rounded up because grout is sold in sealed bags. Step four: estimated_cost = bags × price_per_bag. Worked example: 100 sq ft of 12x12 in tile, 1/4 in thick, 1/8 in joints gives about 0.21 kg per m2, roughly 2.16 kg (4.77 lb) with 10% waste, which fits in one 25 lb bag.
Grout choice is decided by joint width and tile surface. Use sanded grout for joints 1/8 in (3 mm) and wider: the sand locks the joint together, resists shrinkage cracking, and stands up to floors and heavy traffic. Use unsanded grout for joints under 1/8 in and for delicate surfaces like glass tile or polished stone, where sand particles can scratch the finish during cleanup. Epoxy grout is the third option: far more stain and chemical resistant and nearly waterproof, which makes it popular for shower floors, but it is harder to work with and more expensive. Match the type to your joint width first, then to the tile.
Coverage rises with joint width and falls with tile size, because smaller tiles create more joints per square foot. Planning figures from manufacturer coverage tables: a 12x12 in tile with 1/8 in joints needs roughly 1 lb of grout per 14 sq ft; with 1/4 in joints, about 1 lb per 10 to 12 sq ft. A 6x6 in tile with 1/8 in joints needs about 1 lb per 7 sq ft, and mosaic tile can need three to five times the grout of large-format tile over the same area. Doubling the joint width roughly doubles the grout. Always check the coverage printed on your specific grout bag, since products vary, and use the label figure for the final purchase. Think of the figures above as a quick coverage chart and estimator: pair them with the joint width guide (the 1/8 in threshold for sanded vs unsanded) and a 10% waste factor, and you will land within a bag of the calculator's exact figure.
Grout is sold in 10 lb and 25 lb bags or boxes. Always round up to whole bags: a half bag is cheaper than a second trip to the store mid-job, and leftover grout keeps for touch-ups. Buy every bag for one continuous area from the same production batch, because shade can vary slightly between batches and the difference shows once the grout cures. Store unopened bags in a dry place; an opened bag absorbs moisture from the air and may not cure properly months later. For large areas, confirm the final number with the coverage table on the bag label.
It depends on tile size and joint width. A 12x12 in tile with 1/8 in joints needs roughly 1 lb per 14 sq ft; with 1/4 in joints, about 1 lb per 10 to 12 sq ft. Smaller tiles need much more: a 6x6 in tile with 1/8 in joints needs about 1 lb per 7 sq ft. Enter your exact tile size and joint width above for a precise figure.
For 100 sq ft of 12x12 in tile with 1/8 in joints and 1/4 in thickness, you need about 4.8 lb of grout including a 10% waste allowance, which fits in one 25 lb bag. With 1/4 in joints the same floor needs about 9.5 lb. Wider joints and smaller tiles raise the number quickly, so always calculate for your exact layout.
Use sanded grout for joints 1/8 in (3 mm) and wider: the sand prevents shrinkage cracking and stands up to floors and traffic. Use unsanded grout for joints under 1/8 in and for delicate tile like glass or polished stone, which sand can scratch. Epoxy grout is the premium option for wet areas like shower floors: nearly waterproof and stain-proof, but harder to apply.
Divide the total grout needed (with waste) by the bag weight and round up, since grout is sold in sealed bags. For example, 13 lb of grout with 10 lb bags means 2 bags. Grout commonly comes in 10 lb and 25 lb bags; a 25 lb bag covers roughly 250 to 350 sq ft of 12x12 tile with 1/8 in joints.
Epoxy grout is made from epoxy resins and filler powder instead of cement. It is nearly waterproof, highly stain and chemical resistant, and does not need sealing, which makes it the best choice for shower floors, kitchen counters, and commercial kitchens. The trade-off is price and workability: it costs more and sets faster, so it is harder for beginners to apply.
Yes. The calculator works for any flat tiling project: floors, walls, and backsplashes. The math is the same; only the tile size, thickness, and joint width change. Backsplashes often use small tiles with narrow joints, so remember to pick unsanded grout for joints under 1/8 in to protect the tile surface.
Yes, always add 10 to 15%. Mixing loss, spillage, grout left in the bucket, and small measuring errors are unavoidable, and running out mid-job risks a shade mismatch between batches. The calculator applies your waste percentage automatically.
It is best not to. Grout shade can vary slightly between production batches, and mixing bags from different batches can leave visible tone differences once cured. Buy all bags for one continuous area from the same batch, note the batch number on your receipt, and keep one sealed bag for future repairs.
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