What is the difference between sanded and unsanded grout?

Sanded grout contains fine sand and is used for joints 1/8" (3mm) or wider. It is stronger and resists shrinkage. Unsanded grout is smoother and used for joints narrower than 1/8", such as on delicate tile surfaces. Epoxy grout can be used for any joint width and offers superior chemical resistance.

How do I measure joint depth?

Joint depth equals the thickness of the tile. Standard ceramic tiles are about 1/4" (6mm) thick; porcelain and natural stone tiles are often 3/8" (9.5mm) or more. Check the tile packaging for exact thickness.

Why add a waste factor?

Grout is mixed in batches and the exact coverage varies with tile surface texture and joint consistency. A 10% waste factor accounts for mixing losses, leftover in the bucket, and slightly uneven joints. Use 15% for rough-textured or natural stone tiles.

How accurate is this formula?

The formula — (L+W)/(L×W) × joint width × joint depth × area × grout density — gives a reliable estimate for standard rectangular tiles. Actual usage may vary ±10% depending on application technique, tile texture, and grout consistency.

What grout density is used?

This calculator uses the standard density of 100 lb/ft³ for portland-cement-based grout (sanded or unsanded). Epoxy grouts have slightly different densities; check the product data sheet for precision.

Tile Grout Calculator

Name: Tile Grout Calculator
Availability: InStock
Author: Nham Vu

Enter your tile size, joint dimensions, and area to instantly calculate how many pounds of grout you need including bags.

Project Details

Total Area to Tile

Tile Size

Grout Joint Width

Joint Depth (Tile Thickness)

Waste Factor: 10%

0%10%20%30%

Fill in the project details and click Calculate Grout to see results.

Grout Type Guide

Sanded Grout

Joint width ≥ 1/8" (3 mm). Contains fine sand for strength. Recommended for floors and wide joints. Resists shrinkage cracking.

Unsanded Grout

Joint width < 1/8" (3 mm). Smooth formula for tight joints. Ideal for wall tiles and polished stone surfaces where sand would cause scratching.

Epoxy Grout

Any joint width. Two-part resin formula with high chemical resistance and near-zero water absorption. Best for kitchens, labs, and commercial floors.

Summary

Enter your tile size, joint dimensions, and area to instantly calculate how many pounds of grout you need including bags.

How it works

Enter the total area to tile in square feet or square meters.
Select a preset tile size or enter custom tile length and width in inches.
Choose the grout joint width from common values or enter a custom width.
Set the joint depth (typically equal to tile thickness: 1/4" or 3/8").
Adjust the waste factor percentage (default 10%).
Results show grout weight in lbs (and kg), plus bags needed for 10 lb, 25 lb, and 50 lb bag sizes.

Use cases

Estimate grout materials before visiting the tile supply store.
Compare grout quantities for different tile sizes on the same area.
Determine whether sanded or unsanded grout is appropriate for your joint width.
Calculate grout needed for both floor and wall tile installations.
Budget material costs by knowing the exact number of grout bags required.

Frequently Asked Questions

Last updated: 2026-06-13 · Reviewed by Nham Vu