Tile Grout Calculator
Calculate how much grout you need by tile size, joint width, and area — with brand-specific bag counts.
Bags Needed by Brand
| Brand | Bag Size | Bags Needed |
|---|---|---|
| Mapei Keracolor U (Unsanded) | 10 lb bag | 1 |
| Mapei Keracolor S (Sanded) | 25 lb bag | 1 |
| Laticrete Permacolor Select | 25 lb bag | 1 |
| TEC Power Grout | 25 lb bag | 1 |
| Custom Prism | 17 lb bag | 1 |
| Bostik TruColor | 9 lb bag | 1 |
Coverage varies by tile size and joint dimensions. Add 10-15% extra for waste.
How It Works
This calculator estimates grout quantity based on your tile dimensions, grout joint width and depth, and total area. It then shows how many bags you need for popular grout brands.
Formula: Grout (lbs) = Area × [(Tile Length + Tile Width) × Joint Width × Joint Depth / (Tile Length × Tile Width)] × 0.072 (density factor).
The density factor converts cubic inches of joint volume to pounds of cured grout. Results are rounded up to full bags for each brand.
Sanded vs Unsanded: Use sanded grout for joints 1/8" (3mm) and wider. Use unsanded grout for joints narrower than 1/8". This calculator automatically recommends the correct type based on your joint width.
Frequently Asked Questions
How much grout do I need per square foot?
The amount of grout per square foot depends on tile size, grout joint width, and joint depth. Small mosaic tiles (2x2) with 1/8" joints need about 1.5 lbs per sq ft. Large format tiles (24x24) with the same joints need about 0.15 lbs per sq ft. Use this calculator for an exact amount based on your tile and joint dimensions.
When should I use sanded vs unsanded grout?
Use unsanded grout for joints narrower than 1/8 inch (3mm). Use sanded grout for joints 1/8 inch and wider. Sanded grout is stronger and resists cracking in wider joints. Unsanded grout is smoother, easier to work into narrow joints, and less likely to scratch polished stone or glass tile.
How do I calculate grout joint volume?
Grout volume per square foot = (Tile Length + Tile Width) x Joint Width x Joint Depth / (Tile Length x Tile Width). This formula calculates the total linear inches of grout joints in a square foot and multiplies by the cross-sectional area of each joint. The result is then multiplied by a density factor to convert to pounds.
Should I buy extra grout?
Yes, always buy 10-15% more grout than calculated. Grout is wasted during mixing, application, and cleanup. If you are mixing colors or working with irregular surfaces, buy 20% extra. Leftover sealed bags can be returned, but running short mid-project means a second trip and potentially a different dye lot.
What grout joint width should I use?
Standard joint widths: 1/16" for rectified large format tiles, 1/8" for most wall tiles and subway tile, 3/16" for floor tiles, and 1/4" or wider for rustic or handmade tiles. Wider joints are more forgiving of tile size variation and easier to fill evenly.