TryBuildCalcGrout Calculator (Tile Joint Grout Quantity)
Calculate grout quantity, bags, wastage, and cost.
🕒 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.
Please enter valid tiled area
Common tile sizes
Please enter valid tile length
Please enter valid tile width
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
Enter tiled area and joint details to see material requirements
Grout Calculator: How Much Grout, How Many Bags, and What Will It Cost?
If you're asking "how much grout do I need" or "how many bags should I buy," this calculator answers both from the same inputs. It estimates grout volume and weight from your tiled area, tile size, and grout joint width and depth — not a flat "kg per square meter" guess that ignores how much joint length your specific tile size actually creates.
It's built around how grout consumption actually works: smaller tiles create far more joint length per square meter than large-format tiles, so the same tiled area can need several times more grout depending on tile size alone. A Grout Type preset (cement sanded/unsanded, or epoxy) auto-fills a typical density and wastage allowance, and a Multiple Areas mode combines a floor and a wall — or several rooms with different tile sizes and grout products — into one bag count and cost.
What makes this calculator different:
Most grout calculators leave grout type as a single flat density figure you have to look up. This one ties density and wastage to a named Grout Type so you don't need to know the manufacturer's exact number, still lets you override either field manually, and doesn't force you to work out an area by hand first — since grout depends on tile size and joint geometry rather than room shape, Calculation Modelets you enter the tiled area directly, or have it calculated from room length and width if that's what you already have.
Applicable standards:
- ANSI A118 (cement-based) and ANSI A118.3 (epoxy) classify grout performance, but don't change this calculator's quantity math
- Movement joints at perimeters, changes of plane, and every 25-40m² on large areas are never filled with grout — outside this calculator's scope
- This calculator estimates material quantity and cost only, not grout selection, colour matching, or substrate/tile suitability
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.
Enter valid area and joint details above to generate the detailed worked example.
Essential Checklist+−
Complete these critical checks before approving the work or proceeding to the next construction stage.
✓Area and Joint Dimensions+-
- Tile area was measured on site after tiling was complete — not calculated from room dimensions alone.
- Joint width was measured on the actual laid tiles — not assumed from the tile specification sheet.
- Tile thickness was measured from the actual tile — manufacturer's nominal thickness can vary by 0.5-1mm.
- Floor and wall areas with different joint widths, tile sizes, or grout products were calculated separately using Multiple Areas.
- Dimensions were entered in consistent units.
✓Grout Type Selection+-
- Grout type is appropriate for the joint width — unsanded grout for joints under 3mm, sanded grout for joints 3-12mm.
- Epoxy grout is specified for wet areas, chemical exposure, food preparation areas, and joints under 3mm where high hygiene is required.
- Cement-based grout is not used in joints narrower than 1.5mm — it cannot be packed in and will crack.
- Movement joints (expansion joints) were specified at perimeter, columns, and over structural joints — these are not filled with grout.
✓Coverage and Mixing+-
- Coverage rate used in the calculation matches the grout manufacturer's data sheet for the specific joint width and tile size.
- Water ratio follows the manufacturer's specification — adding extra water weakens grout and causes colour variation.
- Tiles were cleaned of adhesive and dust from joints before grouting — residue prevents grout from bonding to joint edges.
- Tile adhesive was fully cured before grouting commenced — minimum 24 hours for standard adhesive, 48 hours in cold or humid conditions.
✓Wastage and Purchase+-
- Wastage of 8-15% was applied to the calculated grout quantity for mixing residue, application waste, and bag variation.
- All grout was ordered from the same production batch — different batches of the same colour can vary visibly.
- The final quantity including wastage was used for purchase.
Full QC Checklist+−
Verify grout selection, joint dimensions, substrate readiness, mixing, application, and curing.
✓Area and Joint Dimensions+-
- Tile area was measured on site after tiling was complete — not calculated from room dimensions alone.
- Joint width was measured on the actual laid tiles — not assumed from the tile specification sheet.
- Joint width is consistent across the floor or wall — variable joint widths were averaged or calculated in sections.
- Tile thickness was measured from the actual tile — manufacturer's nominal thickness can vary by 0.5-1mm.
- Floor and wall areas with different joint widths, tile sizes, or grout products were calculated separately using Multiple Areas.
- Dimensions were entered in consistent units.
✓Grout Type Selection+-
- Grout type is appropriate for the joint width — unsanded grout for joints under 3mm, sanded grout for joints 3-12mm.
- Epoxy grout is specified for wet areas, chemical exposure, food preparation areas, and joints under 3mm where high hygiene is required.
- Cement-based grout is not used in joints narrower than 1.5mm — it cannot be packed in and will crack.
- Colour-matched grout was selected before tiling started — matching grout colour to existing laid tiles post-installation is unreliable.
- Anti-fungal grout is specified for bathrooms, wet rooms, and areas with persistent moisture.
- Movement joints (expansion joints) were specified at perimeter, columns, and over structural joints — these are not filled with grout.
✓Coverage and Mixing+-
- Coverage rate used in the calculation matches the grout manufacturer's data sheet for the specific joint width and tile size.
- Grout was mixed in small batches — only as much as can be applied and cleaned in 20-30 minutes.
- Water ratio follows the manufacturer's specification — adding extra water weakens grout and causes colour variation.
- Tiles were cleaned of adhesive and dust from joints before grouting — residue prevents grout from bonding to joint edges.
- Tile adhesive was fully cured before grouting commenced — minimum 24 hours for standard adhesive, 48 hours in cold or humid conditions.
✓Wastage and Purchase+-
- Wastage of 8-15% was applied to the calculated grout quantity for mixing residue, application waste, and bag variation.
- All grout was ordered from the same production batch — different batches of the same colour can vary visibly.
- Sufficient grout for a test area was set aside and cured before ordering the full quantity — confirms colour match.
- Grout sealer requirement was confirmed — unglazed tiles and natural stone need sealing before grouting to prevent staining.
- The final quantity including wastage was used for purchase.
Reference Tables
Approximate grout weight by tile size
For 20 m² tiled area, 3 mm joint width, 8 mm joint depth, 1600 kg/m³ density, no wastage.
| Tile Size | Approx. Grout Weight | Why it changes |
|---|---|---|
| 300 x 300 mm | 5.12 kg | More joints per m² |
| 600 x 600 mm | 2.56 kg | Fewer joints per m² |
| 800 x 800 mm | 1.92 kg | Large format tile |
Grout type reference
| Grout Type | Typical Density | Typical Wastage | Best For |
|---|---|---|---|
| Cement — Unsanded | 1650 kg/m³ | 8% | Joints under 3mm |
| Cement — Sanded | 1600 kg/m³ | 10% | Joints 3-12mm |
| Epoxy | 1750 kg/m³ | 15% | Wet areas, chemical resistance, joints under 12mm |
Typical grout joint width by tile type
| Tile Type | Typical Joint Width |
|---|---|
| Rectified/precision-edge porcelain | 1.5-3 mm |
| Standard glazed floor/wall tile | 3-5 mm |
| Rustic/handmade tile | 5-8 mm |
| Outdoor pavers, natural stone | 8-12mm+ |
Confirm density, coverage, and joint width against the specific grout product's technical data sheet before finalizing an order — these figures are general planning guidance only.
How to Use the Grout Calculator
- Enter your total tiled area and tile size, or switch on Multiple Areas for floor + wall (or several rooms) in one pass.
- Enter your grout joint width and depth — joint depth is usually close to tile thickness unless the joint is only partially filled.
- Select a Grout Type matching your product — this auto-fills a typical density and wastage, both still editable.
- Set bag size, then switch on cost estimation if you want an estimated total cost.
Practical Grout Estimation Tips
- Use actual tile size instead of nominal size when possible — real tile dimensions can differ slightly from the catalogue figure.
- Use tile thickness as joint depth only when the full depth will be filled with grout, not just a surface skim.
- Add more wastage for textured or rustic tiles, since grout residue is harder to clean off a rough surface before it hazes.
- Check the grout manufacturer's coverage chart for final ordering when the product datasheet is available — it accounts for the exact formulation, not just a generic density figure.
- Buy all grout for one continuous area from the same production batch — colour can vary visibly between batches even with the same product code.
Common Mistakes
- Using a flat "kg per square meter" figure instead of accounting for tile size — small tiles need far more grout per m² than large-format tiles for the same area.
- Using cement-based grout in joints narrower than 1.5mm — it can't be packed in properly and will crack; unsanded grout or epoxy is needed for very fine joints.
- Skipping wastage entirely — mixing residue, float loss, and colour-match test patches are never free, and running short mid-job risks a visible batch mismatch.
- Using tile thickness as joint depth when the joint is only partially filled — overstates the requirement for thick pavers or deep-set tiles.
- Grouting before the tile adhesive has fully cured — minimum 24 hours for standard adhesive, longer in cold or humid conditions, or the tiles can shift.
- Mixing grout bags from different production batches on a visible feature wall or floor — even the same product code can show a shade difference batch to batch.
Grout Calculator Limitations
- This calculator provides an estimate only and does not replace the grout manufacturer's technical data sheet.
- It does not include tile adhesive, tile spacers, sealant, or substrate preparation materials — use the Tile Adhesive Calculator separately for those.
- Grout Type presets are general planning defaults — actual density and coverage depend on the specific product and its exact formulation.
- Consumption can vary by tile edge shape, tile surface texture, installer technique, cleanup loss, and how fully the joint depth is packed, beyond what any calculator can predict.
- Very irregular tiles, handmade tiles, mosaic sheets, stone cladding, and heavily textured surfaces may need more grout than a standard rectangular tile estimate.
Related Construction Calculators
You may also find these calculators useful for the same tiling job:
- Tile Calculator
Estimate tile quantity and boxes for the same area.
- Tile Adhesive Calculator
Estimate adhesive bags required before grouting.
- Waterproofing Calculator
Estimate waterproofing before tiling bathrooms or wet areas.
- Paint Calculator
Estimate paint for adjoining walls or ceilings.
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.