Are you struggling to figure out how much grout you actually need for your tiling or construction project? It can be frustrating to juggle measurements like tile size, joint width, and waste factors while trying to avoid running out of grout—or overspending on extra bags.
That’s why we built this simple Grout Volume Calculator. In this article, you’ll not only get a free tool to calculate grout volume instantly, but you’ll also understand the formulas behind the math.
By the end of this page, you’ll be able to confidently calculate the grout volume for your project and make more informed purchasing decisions.
How to Use This Calculator:
- Enter Length: This is the total length of the area to be grouted (in feet, meters, or inches).
- Input Width: The total width of the grouted area.
- Add Joint Depth: This is the thickness of the tile or depth of the grout joint.
- Input Waste Percentage: The extra material allowance, usually between 10–15%.
- Click “Calculate”: Your result, the total grout volume needed, will be displayed instantly.
The Formula Explained: How It All Works
For those who like to see the magic behind the curtain, here is the exact formula our Grout Volume Calculator uses.
Rectangular or Square Area Grout Volume
Grout Volume=Length×Width×Joint Depth×(1+Waste Percentage)Grout\ Volume = Length \times Width \times Joint\ Depth \times (1 + Waste\ Percentage)Grout Volume=Length×Width×Joint Depth×(1+Waste Percentage)
- Length: Length of the grouted area.
- Width: Width of the grouted area.
- Joint Depth: Depth of the grout joint (usually tile thickness).
- Waste Percentage: Extra grout added to account for wastage.
Tile Grout Volume (More Specific for Tile Installations)
Formula 1: Grout per Unit Area Grout per Unit Area=((Tile Length+Grout Joint Width)×(Tile Width+Grout Joint Width))−(Tile Length×Tile Width)Grout\ per\ Unit\ Area = ((Tile\ Length + Grout\ Joint\ Width) \times (Tile\ Width + Grout\ Joint\ Width)) – (Tile\ Length \times Tile\ Width)Grout per Unit Area=((Tile Length+Grout Joint Width)×(Tile Width+Grout Joint Width))−(Tile Length×Tile Width)
Formula 2: Simplified Tile Grout Volume Grout Volume=(Total Tiled Area×Grout Joint Width×Grout Joint DepthTile Length×Tile Width)×(Tile Length+Tile Width)2×(1+Waste Percentage)Grout\ Volume = \left(\frac{Total\ Tiled\ Area \times Grout\ Joint\ Width \times Grout\ Joint\ Depth}{Tile\ Length \times Tile\ Width}\right) \times \frac{(Tile\ Length + Tile\ Width)}{2} \times (1 + Waste\ Percentage)Grout Volume=(Tile Length×Tile WidthTotal Tiled Area×Grout Joint Width×Grout Joint Depth)×2(Tile Length+Tile Width)×(1+Waste Percentage)
- Total Tiled Area: Overall surface area being tiled.
- Grout Joint Width: Width of grout gaps.
- Grout Joint Depth: Usually equal to tile thickness.
- Tile Length: Length of one tile.
- Tile Width: Width of one tile.
- Waste Percentage: 10–15% added to avoid shortages.
Converting Volume to Practical Units
- Cubic Inches → Gallons (US): Gallons = Cubic Inches ÷ 231
- Cubic Feet → Gallons (US): Gallons = Cubic Feet × 7.48052
- Cubic Feet → Liters: Liters = Cubic Feet × 28.3168
- Cubic Meters → Liters: Liters = Cubic Meters × 1000
Practical Example: Let’s Walk Through It
Let’s imagine you want to calculate grout volume for a tiled bathroom wall.
Scenario Data
- Tile Length: 30 cm
- Tile Width: 30 cm
- Tile Thickness (Grout Depth): 8 mm
- Grout Joint Width: 3 mm
- Total Tiled Area: 12 m²
- Waste Percentage: 10% (0.10)
Calculation
Grout Volume=(12×0.3×0.830×30)×(30+30)2×1.10Grout\ Volume = \left(\frac{12 \times 0.3 \times 0.8}{30 \times 30}\right) \times \frac{(30 + 30)}{2} \times 1.10Grout Volume=(30×3012×0.3×0.8)×2(30+30)×1.10 Grout Volume≈2.64 LitersGrout\ Volume \approx 2.64 \, LitersGrout Volume≈2.64Liters
The Result
You would need approximately 2.64 liters of grout. With packaging usually sold in bags or pre-mixed buckets, you’d round up to the nearest available size to ensure full coverage.
Grout Conversion & Quick Reference Table
| Tile Size (cm) | Joint Width (mm) | Tile Thickness (mm) | Coverage per 1kg Grout (m²) |
|---|---|---|---|
| 10 x 10 | 3 | 5 | ~1.2 |
| 30 x 30 | 3 | 8 | ~3.5 |
| 30 x 60 | 2 | 8 | ~5.0 |
| 60 x 60 | 3 | 10 | ~6.0 |
Helpful Tips & Tricks
- Always round up: It’s better to have a little extra grout than to run out mid-project.
- Check product yield: Different grout brands provide different coverage, so always confirm with manufacturer guidelines.
- Consider project type: Floors often require more grout depth compared to walls.
FAQs
It is very accurate if you use consistent measurements and the correct grout yield. Still, always include a waste percentage to avoid running short.
A safe range is 10–15%. If you are working with uneven tiles or an irregular surface, go for the higher end.
Grout packaging or the technical data sheet provided by the manufacturer will list exact coverage values per bag or container.