TryBuildCalcBathroom Grout Calculator (Tile Grout Bags & Cost)
Estimate grout for bathroom floors and walls with higher wastage for corners and cuts.
🕒 Last updated: July 14, 2026
Inputs
Section 1: Tiled Area & Tile Size
ℹ️Known-area mode is quickest if you already have the tiled area. Use room dimensions if you'd rather enter length and width directly.
ℹ️Use total floor or wall tile area. Room dimensions are not required.
Common tile sizes
Section 2: Grout Joint
ℹ️Typical grout joints are 2-5 mm for standard floor and wall tile.
ℹ️Usually close to tile thickness, unless the joint is only partially filled.
Section 3: Grout Type & Wastage
ℹ️Auto-fills a typical density and wastage for the selected type — both remain editable, and Custom leaves them fully manual.
ℹ️kg/m³. Check the product datasheet for the most accurate figure.
ℹ️8% for unsanded cement grout, 10% for sanded cement grout, 15% for epoxy or textured tile.
Section 4: Bags
Section 5: Cost
Recommended grout: 3.86 kg (1 bags)
Tiled area: 12.00 m²
Grout Volume & Weight
Tiled Area: 12.00 m²
Grout Volume: 1.92 litres (0.0019 m³)
Grout Weight (before wastage): 3.36 kg
Wastage Added: 0.50 kg
Final Grout Required: 3.86 kg
Bags & Coverage
Bags Required: 1 bags
Coverage per Bag: 17.86 m²
Quick Insight
Buy at least 1 bags from the same production batch.
Calculated from tiled area, tile size, and grout joint dimensions.
Assumptions Used
Grout volume from joint width, joint depth, and tile size | Bag count rounded up to the next whole bag | Colour-matched bags should come from the same production batch.
Bill of Materials
Main material: 1 bags + recommended tools
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Bill of Materials
Main material: 1 bags + recommended tools
Computed items reflect your entered area and joint dimensions; consumables below are general recommendations — actual needs vary by product and site.
For Your Job
Grout
1 bags
3.86 kg total
General Tools & Consumables
Grout float (rubber)
Bucket & sponge
Mixing paddle & drill
Grout sealer
Approximate results for planning only. Verify with a professional.
Looking for the verification checklist, reference tables, or tips and mistakes?See the complete Grout Calculator.
Bathroom grout estimate
This page uses a 12 m² bathroom with 300x300mm tiles and epoxy grout — 3.36 kg of grout, about 3.86 kg after the higher 15% wastage, still 1 bag at 5 kg.
This page uses higher wastage for bathroom corners and cut tiles, with epoxy grout as the default for wet-area resistance.
- Area: 12 m².
- Wastage: 15%.
- Tile: 300 x 300 mm.
- Grout type: Epoxy.
How grout quantity is calculated
The calculation uses the tiled area and the approximate volume of grout joints created by the tile grid. Wider joints, deeper joints, and smaller tiles all increase grout quantity.
Step 1 - Calculate grout volume
Area = Room Length x Room Width, or entered known area
Volume = Area x Joint Width x Joint Depth x (Tile Length + Tile Width) / (Tile Length x Tile Width x 1000)
Multiple Areas = Sum of every area's volume above, combined into one total
Calculation Mode lets you enter tiled area directly or let the calculator work it out from room length and width — both feed the same volume formula. Each tile contributes one joint-width strip along its length and one along its width, so smaller tiles create proportionally more joint volume per m² than larger ones. Switching on Multiple Areas lets you combine floor, wall, or several rooms with different tile sizes, joint dimensions, and grout products in one run.
Step 2 - Convert volume to weight
Grout Weight = Grout Volume x Grout Density
Selecting a Grout Type auto-fills a typical density (around 1600-1650 kg/m³ for cement-based, 1750 kg/m³ for epoxy) — always editable, and best replaced with the exact figure from your product's datasheet when available.
Step 3 - Add wastage and calculate bags
Final Grout = Grout Weight x (1 + Wastage / 100)
Bags = ROUND UP(Final Grout / Bag Size)
Wastage covers mixing residue, tooling loss, and colour-match test patches — auto-suggested from Grout Type (8% unsanded, 10% sanded, 15% epoxy) and always overridable. Bag count is rounded up because grout is purchased in full bags.
Step 4 - Calculate cost
Cost = Bags x Price per Bag
Cost only appears when Enable Cost Estimation is switched on and a price per bag is entered, shown in your selected currency.
Real-World Grout Calculation Example
This example uses the active inputs above and follows the same steps from the formula section.
Input Values Used
| Input | Value |
|---|---|
| Tiled area | 12 m² |
| Tile size | 300 mm × 300 mm |
| Joint width / depth | 3 mm / 8 mm |
| Grout type | Epoxy (wet areas, chemical resistance, joints under 12mm) |
| Density | 1750 kg/m³ |
| Wastage | 15% |
| Bag size | 5 kg |
Step 1 — Grout Volume
| Calculation | Formula / Substitution | Result |
|---|---|---|
| Grout volume | 12 m² × 3 mm × 8 mm × (300 + 300) / (300 × 300 × 1000) | 0.0019 m³ (1.92 L) |
Step 2 — Grout Weight
| Calculation | Formula / Substitution | Result |
|---|---|---|
| Grout weight | 0.0019 m³ × 1750 kg/m³ | 3.36 kg |
Step 3 — Wastage and Bags
| Calculation | Formula / Substitution | Result |
|---|---|---|
| Wastage | 3.36 kg × 15% | 0.5 kg |
| Final grout required | Weight + wastage | 3.86 kg |
| Bags required | ROUND UP(3.86 / 5 kg) | 1 bags |
Therefore, for this 12 m² job you need 3.86 kg of grout, or 1 bags.
This page keeps things focused on the calculation above. For the full construction guide — verification checklist, reference tables, usage steps, tips, common mistakes, and limitations.See the complete Grout Calculator.
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Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.