Grout Calculator

How to Calculate Grout

Grout coverage depends on four variables: tile size, joint width, tile thickness, and total floor area. Smaller tiles and wider joints both dramatically increase the volume of grout needed per square foot. A 2 inch mosaic tile needs roughly 4 times more grout per sq ft than a 12x12 tile because of the much larger total joint length. This calculator uses the standard ANSI-based formula to give an accurate bag count for any combination.

Grout Volume Formula

The volume of grout needed per unit floor area follows this formula, where L and W are tile dimensions, Gap is joint width, and Thickness is the joint depth (usually equals tile thickness):

Multiply by your total area, then by grout density (~120 lb/cu ft, or ~1,920 kg/cu m) to get dry-weight in pounds or kilograms. Finally divide by bag weight and round up:

Grout Type Comparison

Coverage Chart by Tile Size

Quick reference for a 25 lb bag of standard sanded grout with 1/8 in joints and ~5/16 in tile thickness:

Tools Needed

• Mixing bucket + margin trowel - for batch mixing
• Rubber grout float - to press grout into joints at 45° angle
• Grout sponge + clean water - at least 2 buckets; change water frequently
• Microfiber cloth - final buff after haze sets
• Grout sealer + applicator - applied 48-72 hours after cure

Application Steps

1. Wait 24-48 hours after tiling with thinset before grouting
2. Vacuum joints to remove thinset ridges and dust
3. Mix small batches - pot life is 30-45 minutes
4. Apply at 45° diagonally across joints with rubber float
5. Initial clean 10-15 minutes after application with damp sponge
6. Haze removal 2-4 hours later with dry microfiber
7. Seal after 48-72 hours full cure (cement grouts only)