Ceramic Tile Grout Calculator

Explanation

Grout quantity depends on the empty space between tiles, not just the tile area. The joint width and the tile thickness determine the volume of grout per unit area. A small change in joint width can significantly change the amount of grout required, especially across large floors or walls. This calculator uses a common approach that approximates grout volume from tile geometry: the joint width times tile thickness times the perimeter density of tiles across the total area.

The perimeter density factor accounts for how many joint lines occur per unit area. For a tile with length L and width W, there are joint lines every L and W, so the grout volume per area is proportional to (1/L + 1/W). Multiplying by total area yields the total joint volume. The tool then converts that volume into gallons or liters and estimates dry mix weight using a typical grout density. This helps you plan bag quantities and avoid running short mid-installation.

This estimator assumes that joints are filled to tile thickness. If you plan to leave joints shallow or use a different setting technique, reduce the thickness input to match the expected grout depth. For large format tiles, expansion joints, and specialty grout mixes, consult manufacturer data sheets. Use this calculator for quick material estimation and ordering, then verify with field conditions and product coverage charts.

Surface texture also affects grout usage. Tiles with chamfered edges or pillow profiles create a slightly wider void, so grout volume can increase. For mosaic sheets, the joint density is much higher than for large format tiles, so grout consumption rises quickly. When in doubt, increase the estimate by a small buffer so you have enough grout to finish the installation without color-matching issues between batches. Keep a spare bag for future repairs.

Formula

Grout volume: V = area x jointWidth x tileThickness x (1/tileLength + 1/tileWidth)

Gallons: gal = V / 231 (for cubic inches)

Weight: lb = gal x 12 (typical dry grout density)

Example Calculation

A 100 sq ft floor with 12x12 in tiles, 1/8 in joints, and 0.35 in thickness yields about 1.0 gallons of grout or roughly 12 lb of dry mix. Always add a buffer for waste and cleanup.

FAQs

Do I need to add waste?

Yes. Add extra grout for mixing loss, cleanup, and uneven joints.

What grout density should I use?

This tool uses a typical 12 lb per gallon estimate. Check your product label for exact yield.

Can I use this for mosaic tile?

Mosaic tiles have more joints, so grout usage is higher. Use smaller tile dimensions for accuracy.

Should I include expansion joints?

Expansion joints are usually filled with flexible sealant, not grout. Subtract those areas if needed.

Does tile thickness include thinset?

No. Use the tile thickness only, unless you plan to fill joints deeper than tile thickness.

How it works

This tool estimates grout volume from tile geometry and joint width, then converts to weight for material planning. All calculations run client-side.

Disclaimer

Results are estimates. Verify grout coverage with manufacturer data and add a waste factor for cleanup and mixing loss.