Grout Calculator
By: Jack MartinFree Tile Grout Calculator
Our tile grout calculator instantly shows exactly how much grout you need — sanded, unsanded, or epoxy — based on your tile size, joint dimensions, and total area. Professional accuracy, completely free.
Quick Answer
Most tile projects need between 0.3 and 4 lbs (0.15–1.8 kg) of grout per square foot, depending on tile size and joint width. Large-format tile (18×18" or bigger) with narrow 1/16" joints needs as little as 0.3–0.5 lb/sq ft, while small mosaic tile with wide joints can need 3–4 lb/sq ft. A standard 25 lb bag of sanded grout typically covers 80–120 sq ft of average residential floor tile. Use the tile grout calculator below for your exact amount.
Grout Calculator
Fill in your project details below
Step 2 — Tile Dimensions
Step 3 — Grout Joint Size
Step 4 — Total Area
Your Grout Estimate
| Detail | Value |
|---|---|
| Net grout volume | — |
| Waste included | — |
| Total inc. waste | — |
| Tiles per m² | — |
| Area calculated | — |
How to Use This Tile Grout Calculator
Get a precise grout estimate in under 60 seconds
Our free tile grout calculator uses a standard grout-joint volume and density formula to give you a practical estimate of how much grout you need for any tiling project. Whether you are tiling a small bathroom backsplash, a large kitchen floor, or an entire home renovation, this tool removes the guesswork and helps you buy the right amount of grout the first time — avoiding costly return trips to the hardware store or wasting money on bags you never use.
Simply select your grout type, enter the tile dimensions, set the joint width and actual grout fill depth, choose a waste buffer percentage, and input your total area. The calculator instantly shows you the amount required plus the number of bags to purchase — in kilograms and 5 kg bags under Metric units, or pounds and standard 25 lb bags under Imperial units.
Once your grout has cured and you're ready for ongoing maintenance, our guides on the best bathroom grout cleaners and homemade shower cleaner recipes cover how to keep it looking new.
Choose Grout Type
Sanded, unsanded, or epoxy — each has a different density that directly affects your quantity estimate
Enter Tile Size
Width and height of one tile in cm or inches — do not include the grout joint gap in this measurement
Set Joint Size
Joint width (spacer size) and actual grout fill depth in mm — both affect total grout volume significantly
Enter Total Area
Total floor or wall area in m² or ft² — measure each room section and add them together for the full total
The Grout Calculation Formula Explained
standard grout-joint volume method for practical coverage estimates
Joint Perimeter = (Tile Width + Tile Height) ÷ (Tile Width × Tile Height)
Grout Volume/m² = Joint Perimeter × Joint Width × Joint Depth
Grout Weight = Volume × Density × Total Area × (1 + Waste Factor)
Default density estimates: Sanded 1.92 kg/L (120 lb/ft³) · Unsanded 1.75 kg/L (109 lb/ft³) · Epoxy 1.85 kg/L (115 lb/ft³). Actual density varies by product.
The formula calculates grout-joint length per unit area, multiplies it by the joint width and the actual grout fill depth, then converts the resulting volume to weight using the selected default density. A configurable waste factor is then applied. Similar joint-volume and coverage methods are published by major grout manufacturers, but product coverage and density can vary by brand.
Sanded vs. Unsanded vs. Epoxy Grout
Choosing the wrong grout type leads to cracking, scratching, and expensive rework
Sanded Grout
Contains fine silica sand that prevents shrinkage and cracking in wider joints. Use for any joint 3mm (⅛ inch) or wider. Ideal for ceramic and porcelain floor tiles, outdoor tiles, and high-traffic areas. Never use on polished marble, glass, or glazed surfaces — sand particles will permanently scratch the finish. See our full sanded vs unsanded grout comparison for more detail.
Unsanded Grout
Smooth, fine-grained grout for narrow joints under 3mm. Preferred for wall tiles, polished marble, travertine, glass mosaic, and any surface that scratches easily. Do not use in joints wider than 3mm or cracking will develop.
Epoxy Grout
Two-component resin-based grout offering superior stain, chemical, and moisture resistance. The right choice for commercial kitchens, swimming pools, hospitals, and food-preparation surfaces. Requires no sealing after installation.
Polymer-Modified Grout
Cement grout enhanced with latex or acrylic additives for improved flexibility, adhesion, and crack resistance. An excellent upgrade for bathrooms, showers, and underfloor-heated tiles without the cost of full epoxy.
Grout Joint Width Reference Guide
Correct joint width by tile type — enter this value into the calculator above for accurate results, or see our full grout line size chart for a deeper breakdown by tile material.
| Tile Type | Joint Width | Grout Type | Typical Application |
|---|---|---|---|
| Mosaic / Glass tiles | 1–2mm | Unsanded | Bathroom walls, feature splash panels |
| Glazed wall ceramic | 2–3mm | Unsanded | Kitchen backsplash, shower walls |
| Polished marble / travertine | 1.5–3mm | Unsanded | Bathroom floors and feature walls |
| Standard ceramic floor tile | 3–5mm | Sanded | Kitchen and bathroom floors |
| Porcelain tile | 3–6mm | Sanded | High-traffic floors, outdoor areas |
| Large format tile (600mm+) | 3–5mm | Sanded | Open-plan floors, commercial spaces |
| Natural stone (slate, flagstone) | 6–12mm | Epoxy | Garden paths, heavy-duty exteriors |
| Pool and wet room tiles | 3–6mm | Epoxy | Swimming pools, steam rooms, spas |
Pro Tips for Accurate Grout Estimation
What professional tilers always check before placing their grout order
- Measure tile face only. Enter the tile dimensions without any spacer gap. The joint width is entered separately — adding it to the tile size is the most common calculation error.
- Match joint width to your actual spacer size. Common spacer sizes are 1.5mm, 2mm, 3mm, and 5mm. Even a 1mm difference significantly affects the grout quantity over a large area.
- Use the actual grout fill depth. For a full-depth joint, this is usually close to the tile thickness. If grout fills only part of the joint, enter the actual filled depth instead.
- Standard US grout bags are 25 lb, not 5 kg. If you're shopping in the US, switch the calculator to Imperial units above — it will give you a bag count based on standard 25 lb bags instead of the 5 kg (11 lb) bags common elsewhere.
- Add 15–20% waste for diagonal or herringbone patterns. Angled cuts produce more joint ends per square metre and increase grout consumption considerably.
- Order 15–20% extra on large projects over 50m². Colour batches vary slightly between production runs — running short risks a visible mismatch.
- Porous tiles absorb significantly more grout. Unglazed terracotta, natural slate, and limestone tiles draw grout into their surface — add 20–25% extra to compensate.
- Store leftover grout for future repairs. In a sealed airtight container, unused dry-mix grout remains usable for 12–18 months.
When to Seal Your Grout — and When Not To
Cement-based grout (both sanded and unsanded) is porous and must be sealed 72 hours after installation to prevent staining and moisture ingress. Reseal every 1–3 years depending on foot traffic and cleaning frequency. The easiest test: drop water on the grout surface — if it soaks in rather than beading up, resealing is overdue. Epoxy grout is non-porous and never requires sealing. Full walkthrough here: how to seal grout in 7 easy steps.
Frequently Asked Questions
It depends on tile size and joint width. For a standard 30×30cm tile with a 3mm joint, you typically need 1.2–1.5 kg of sanded grout per m². Smaller 10×10cm mosaic tiles with a 2mm joint can require 3–4 kg/m². Larger format 60×60cm tiles may need only 0.5–0.8 kg/m². Use the calculator above for an exact figure.
For 100 sq ft of standard 12×12" ceramic tile with a 1/8" joint, expect roughly 25–35 lbs of sanded grout — about one to two standard 25 lb bags. Switch the calculator above to Imperial units and enter your exact tile size and joint width for a precise figure.
Yes — the grout-joint volume method can be used for any flat tiled surface. For rooms with multiple tiled surfaces, calculate each surface area separately and add the results together.
Use 10% for straightforward grid-pattern projects, 15% for irregular or porous tiles, 20% for complex patterns, and 25% for first-time DIY work.
Joint width is the horizontal gap between adjacent tiles. Grout fill depth is how deep the grout actually fills that gap. It is often close to tile thickness when the joint is filled fully, but it can be less.
Cement-based grout dries to touch in 2–3 hours but requires 24–72 hours before foot traffic and reaches full strength in 7–14 days. Epoxy grout is typically walk-on ready in 12–24 hours. Once cured, avoid cleaning with vinegar too soon — see does vinegar damage grout for timing guidance.
Epoxy has a density of approximately 1.85 kg/L (115 lb/ft³), versus 1.92 kg/L (120 lb/ft³) for sanded and 1.75 kg/L (109 lb/ft³) for unsanded. Our calculator handles this conversion automatically.
Explore All Free Grout & Tile Tools
Calculators and guides to help you plan, clean, and maintain your grout.