Grout Calculator — How Much Grout Do I Need?

What is a Grout?

This free grout calculator tells you exactly how much grout you need for any tiling project — in kilograms and in 5kg bags — so you buy precisely the right amount. Grout quantity depends on four variables: the total tile area, the tile dimensions, the grout joint width, and the tile thickness. Larger tiles with narrow joints require less grout per square meter. Smaller tiles with wide joints require significantly more. **How Much Grout Do I Need?** The industry-standard formula for grout quantity is: Grout (kg/m²) = ((Tile Length + Tile Width) ÷ (Tile Length × Tile Width)) × Joint Width × Tile Depth × 1.6 — where tile dimensions are in cm and joint/depth measurements are in mm. This formula is used by tile manufacturers worldwide to produce coverage tables on grout packaging. **Typical Grout Coverage Rates:** 600×600cm tiles, 3mm joint, 10mm thick: ~1.6 kg/m² 300×300cm tiles, 3mm joint, 8mm thick: ~1.7 kg/m² 100×100cm tiles, 2mm joint, 8mm thick: ~5.1 kg/m² Mosaic (30×30mm), 2mm joint, 4mm thick: ~12 kg/m² As a general rule: the smaller the tile, the more grout you need per square meter. Small mosaic tiles can require 8–15× the grout of large format tiles at the same joint width. **Grout Joint Width Guide:** Rectified tiles (machine-cut to precise dimensions) can be laid with 2–3mm joints for a near-seamless look. Natural stone and handmade tiles require 5–10mm joints to accommodate dimensional variation. Floor tiles generally use 3mm joints; wall tiles 5mm; rustic or stone tiles 8–10mm.

How to Use This Calculator

Enter the total tile area in square meters — for a room, measure the full floor or wall area, including sections that will be cut around obstacles. Enter the tile length and width in centimeters (e.g., enter 60 for a 60×60cm tile). Select the grout joint width from the dropdown — use 3mm for rectified porcelain, 5mm for standard ceramic wall tiles, and 8–10mm for natural stone or handmade tiles. Select the tile thickness — typically 8–10mm for floor tiles and 6–8mm for wall tiles; check the tile packaging if unsure. Click Calculate to see the total grout needed in kilograms, the grout consumption per square metre, and the number of standard 5kg bags required — all figures include a 10% waste allowance. Round up to the nearest whole bag when ordering.

💡 Pro Tips

• ✓Always buy 10% more grout than calculated — grout is used for waste during mixing, application to areas that absorb more than expected, and accidental dropping.
• ✓Buy all your grout bags from the same batch (same batch number on the label) — slight color variation between batches is common with some manufacturers.
• ✓Mix grout to a consistent peanut butter consistency — too wet makes it weak and prone to cracking; too dry makes it difficult to press into joints.
• ✓Wipe excess grout from tile surfaces within 20–30 minutes of application — once hardened, grout is very difficult to remove without damaging tiles.
• ✓For natural stone tiles (marble, limestone, travertine), use a matching color grout and seal the stone before grouting to prevent staining.
• ✓Epoxy grout is far stronger and stain-resistant than standard cement grout — worth the higher cost for kitchen splashbacks and wet rooms.
• ✓Allow new grout to cure for at least 24–48 hours before allowing water contact; 72 hours before full wet-room use.

Who Uses This Calculator?

DIY homeowners tiling a bathroom floor, kitchen splashback, or shower enclosure who want to buy exactly the right number of grout bags before starting. Professional tilers preparing accurate material take-offs and cost estimates before quoting a client. Tile shop staff advising customers on how much grout to purchase alongside their tile order. Builders and contractors including grout quantities in construction material schedules for new builds or renovations. Renovation managers costing out multiple rooms and needing a reliable grout quantity for each without manual calculations. Anyone who has run out of grout mid-project and wants a precise calculation to avoid repeating the experience. Estimators comparing the grout requirements for large-format tiles versus small mosaic tiles on the same project footprint.

Frequently Asked Questions