Tile Grout Calculator

Tile grout calculator for estimating grout bags from area, tile size, and joint width

If you are planning a tile job, the fastest way to blow a budget is buying too little grout and having to stop mid-install, or buying too much and wasting money. This tile grout calculator is built for one practical decision: estimating how much grout to buy for a standard tiled surface, using the information most people actually know.

You enter the total tiled area (in square meters), your tile size, and the grout joint width. The calculator estimates grout volume, converts that volume into kilograms using a typical grout density, then adds a waste allowance to account for mixing loss, cleanup, uneven joints, and real-world installation variance. Finally, it converts kilograms into the number of bags based on your bag size.

This tool is intentionally focused on field-style estimating for cementitious grout in a typical grid pattern. It is not trying to model every grout type or specialty system. You can still refine the estimate using the Advanced inputs if you know them, but you are not forced to. If you skip Advanced inputs, sensible defaults are used and clearly reflected in the result.

Assumptions and how to use this calculator

• The tile layout is a regular grid with consistent grout joint width across the area.
• Grout depth defaults to 6 mm unless you enter a different depth, since many residential installs do not fully pack the joint to the tile thickness.
• Grout density defaults to 1800 kg/m³, a practical average for cement-based grout. Product-specific density may vary.
• Waste allowance defaults to 10% to cover mixing loss, overfill, sponge cleanup, and small measurement errors.
• Results are estimates for purchasing. Always check your grout packaging coverage guidance and buy enough from the same batch when possible.

Common questions

Why does tile size affect grout quantity?

Smaller tiles create more grout lines per square meter, which increases total joint length. More joint length means more grout volume even if the joint width stays the same. Larger tiles have fewer joints, so grout usage per square meter usually drops.

What grout depth should I use?

If you do not know, leave it blank and use the default. If you want to be more accurate, use an approximate packed depth for the joint, not the tile thickness. Many installs end up with a depth less than full tile thickness because of adhesive ridges and joint packing variation. For deeper joints, grout usage increases linearly.

Is 10% waste realistic?

For typical DIY and normal site conditions, 10% is a reasonable default. If you are new to grouting, have textured tiles, have wide joints, or expect more cleanup, 12% to 20% is safer. If you are a careful installer with controlled mixing and minimal waste, you can reduce it, but do not set it to 0% unless you are willing to risk running short.

Does this work for irregular tiles, mosaics, or very large joints?

Not reliably. This calculator assumes a regular grid tile pattern. Mosaics and irregular layouts can have far more joint length per square meter, so grout usage can be substantially higher. For mosaics, treat the result as a baseline only and increase waste or consider a product coverage chart designed for mosaics.

Why might my grout bag coverage differ from this estimate?

Coverage numbers on bags depend on grout formulation, density, sand content, packing, and the assumptions used by the manufacturer. Your actual joint depth and how tightly joints are packed also matter. Use this calculator to size your purchase, then sanity-check against the specific product coverage table for your tile and joint dimensions.