Grout Calculator
Enter your tile dimensions, joint width, and total area to calculate exactly how many pounds and bags of grout you need — with results broken out by grout type so you can choose the right product for your project.
Please enter valid tile area, tile dimensions, and thickness values.
How to Use This Calculator
- Enter your tile area. Measure or calculate the total square footage of the tiled surface. For floors, multiply the room length by width. For walls, multiply each wall section's width by its height and add the totals.
- Enter your tile dimensions. Use the nominal tile size in inches (e.g., 12 × 12, 4 × 12, 2 × 2 mosaic). For rectangular tiles, enter different values for width and height. Tile thickness is usually 1/4" (0.25") for wall tile and 3/8" (0.375") for floor tile — check the product spec sheet.
- Select the joint width. This is the width of the grout line between tiles. Standard floor tile uses 1/8" joints; large-format tile (18" and larger) typically uses 3/16" or 1/4" joints; mosaic tile uses 1/16" joints.
- Choose your grout type. Unsanded grout is for joints under 1/8". Sanded grout is for joints 1/8" and wider. Epoxy grout works for any joint width and does not require sealing. The calculator shows the correct bag count and warns you if your joint width and grout type may be mismatched.
- Review your results. The total weight and bag count include a 10% waste factor. Purchase the calculated number of bags and keep any leftovers for future repairs — grout color matching between lots can be difficult.
How Grout Weight Is Calculated
- Grout weight per sq ft:
((tile width + tile height) ÷ (tile width × tile height)) × joint width × tile thickness × grout factor - Grout factors:
sanded = 12.5 · unsanded = 10.0 · epoxy = 14.0 (lbs per cubic inch) - Total grout weight:
lbs per sq ft × tile area × 1.10 (10% waste) - 25 lb bags (sanded):
ceil(total lbs ÷ 25) - 10 lb bags (unsanded):
ceil(total lbs ÷ 10) - Epoxy kits:
ceil(total lbs ÷ 9) — epoxy kits are typically sold in ~9 lb units
The industry-standard grout coverage formula accounts for tile size, joint width, and tile thickness. The grout factor (lbs per cubic inch of joint volume) varies by grout type due to differences in aggregate density. All results include a 10% waste buffer for mixing and tooling losses.
Pro Tips
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Recommended Products for This Project
Custom Building Products Polyblend Sanded Grout — 25 lb
Top-rated sanded grout for joints 1/8" to 1/2".
View on Amazon →Mapei Keracolor U Unsanded Grout — 10 lb
Premium unsanded grout for narrow joints and polished stone.
View on Amazon →Laticrete SpectraLOCK Pro Epoxy Grout Kit
Industry-leading epoxy grout for stain-resistant installation.
View on Amazon →Aqua Mix Sealer's Choice Gold — Quart
High-performance penetrating grout sealer, 5-year protection.
View on Amazon →Frequently Asked Questions
What is the difference between sanded and unsanded grout?
Sanded grout contains fine aggregate (sand) that gives it body and prevents excessive shrinkage in wider joints. It is used for joints 1/8 inch wide and larger. Unsanded grout is a smooth paste used for narrow joints under 1/8 inch — it bonds better to vertical surfaces and polished stone that sanded grout would scratch. Using the wrong type is one of the most common tiling mistakes: sanded grout in narrow joints leaves voids; unsanded grout in wide joints cracks as it shrinks.
How many square feet does a 25-pound bag of sanded grout cover?
Coverage depends entirely on tile size, joint width, and tile thickness. A 25-pound bag of sanded grout covers roughly 50–200 sq ft depending on these variables. Small mosaic tiles with many joints consume far more grout than large-format tiles with minimal grout lines. This calculator uses the industry-standard formula to give you an accurate weight for your specific tile and joint dimensions.
Can I grout the same day I set tile?
No. Tile adhesive (thinset or mastic) must cure fully before grouting — typically 24 hours for thinset and 48 hours for mastic. Grouting too soon can shift tiles out of alignment and introduce moisture that prevents the adhesive from curing properly. In cool or humid conditions, wait longer. Check the adhesive manufacturer's data sheet for the minimum cure time before grouting.
How do I mix powder grout correctly?
Add powder to water (not water to powder) for better consistency. Use approximately 1 part water to 4 parts powder by volume as a starting point, but always follow the bag instructions. Mix to a peanut butter consistency with no dry lumps, then let the mixture slake (rest) for 5–10 minutes and stir once more before applying. Do not add more water after slaking — it weakens the grout.
Is epoxy grout worth the extra cost?
Epoxy grout is worth the cost in high-demand environments: commercial kitchens, pool areas, outdoor installations, and anywhere staining or chemical exposure is a concern. It is virtually impervious to stains, does not require sealing, and resists mold and mildew. For standard bathroom or kitchen tile work in a residential setting, quality sanded or unsanded cement grout with a penetrating sealer performs well at a fraction of the cost.