Quick answer
Grout volume = area × (L + W) ÷ (L × W) × joint width × tile thickness. For 100 ft² of 12 × 12 inch tile with 1/8 inch joints and 3/8 inch tile thickness, about 1.84 litres (0.065 ft³, 0.49 US gallon) are needed.
Enter the area, tile size, joint width and tile thickness. The calculator returns grout volume.
Related tools: Tile Calculator: Number of tiles (and boxes) for an area. Cost to Tile a Shower Calculator: Estimated cost from tiled area, material price and labor price. Flooring Calculator: Flooring area with waste, and boxes if you know the coverage per box.
How to use the Tile Grout Calculator
- Enter area (ft²) (above 0).
- Enter tile length (in) (above 0).
- Enter tile width (in) (above 0).
- Enter joint width (in) (above 0).
- Enter tile thickness (joint depth) (in) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Area | A number, in ft² | > 0 |
| Tile length | A number, in in | > 0 |
| Tile width | A number, in in | > 0 |
| Joint width | A number, in in | > 0 |
| Tile thickness (joint depth) | A number, in in | > 0 |
Formula and method
Formula
volume = area × (L + W) ÷ (L × W) × joint width × tile thickness
IEEE-754 double precision; shown to the decimals indicated.
Geometric volume of the joints; check the grout package for coverage per bag because density and waste vary. Plan geometry only; confirm quantities with your supplier and local code before ordering.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Area = 100; Tile length = 12; Tile width = 12; Joint width = 0.125; Tile thickness (joint depth) = 0.375.
| Result | Value |
|---|---|
| Grout volume | 1.84 L |
| Cubic feet | 0.065 |
| US gallons | 0.49 |
Example 2
Inputs: Area = 60; Tile length = 6; Tile width = 24; Joint width = 0.1875; Tile thickness (joint depth) = 0.5.
| Result | Value |
|---|---|
| Grout volume | 2.77 L |
| Cubic feet | 0.098 |
| US gallons | 0.73 |
The first line is the headline result (grout volume). Below it the tile Grout Calculator lists cubic feet and uS gallons, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Why joints matter
Grout fills the joint, so the volume depends on how many joint lengths there are per square foot, their width and depth. Smaller tiles mean more joint length, so a mosaic uses far more grout than a large tile.
Allow for waste
Add 10 to 15% for waste and uneven surfaces. Grout is sold by weight, so check the coverage chart on the bag. The depth used is the tile thickness.
How the result changes with area
Holding every other input at the first worked example, this table changes only area. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Area | Grout volume | Cubic feet | US gallons |
|---|---|---|---|
| 50 | 0.92 L | 0.033 | 0.24 |
| 100 | 1.84 L | 0.065 | 0.49 |
| 200 | 3.69 L | 0.13 | 0.97 |
| 400 | 7.37 L | 0.26 | 1.95 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Area: entering "0" shows "Area must be greater than 0." beside that field and no result.
- Joint width: entering "0" shows "Joint width must be greater than 0." beside that field and no result.
Choosing between the Tile Grout Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Tile Calculator](/construction/tile-calculator/) | area to tile, tile length and tile width | Tiles needed |
| [Cost to Tile a Shower Calculator](/construction/cost-to-tile-shower/) | area to tile, tile price and labor and setting materials | Estimated cost |
| [Flooring Calculator](/construction/flooring-calculator/) | room length, room width and waste allowance | Flooring to buy |
| [Carpet Calculator](/construction/carpet-calculator/) | room length, room width and roll width | Carpet needed |
| [Roof Pitch Calculator](/construction/roof-pitch-calculator/) | i know the and value | Pitch |
Background: construction estimates
Material quantities are geometry plus a margin. Calculate the exact volume or area, add an allowance for waste, spillage, cuts and uneven ground (calculator pages commonly mention 5 to 10 percent, a rule of thumb that varies by material and job) and round up to whole units. One cubic yard is exactly 27 cubic feet.
Suppliers often have minimum order sizes and may charge for small loads, so confirm quantities, product yields and local code with your supplier or a qualified estimator before ordering.
Assumptions and limitations
- Add 10–15% for waste
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for area and joint width to confirm this.
Frequently asked questions
How do I get more coverage?
Use smaller joints with large tiles.
Is sanded or unsanded better?
Sanded for joints wider than 1/8 inch.
Does it include sealer?
No. Grout sealer is bought separately and not estimated here.
What does the Tile Grout Calculator calculate?
Volume of grout needed for a tiled area. It returns Grout volume, Cubic feet and US gallons.
What formula does the Tile Grout Calculator use?
volume = area × (L + W) ÷ (L × W) × joint width × tile thickness. Geometric volume of the joints; check the grout package for coverage per bag because density and waste vary.
What do I need to enter in the tile Grout Calculator?
You enter Area (ft²), Tile length (in), Tile width (in), Joint width (in) and Tile thickness (joint depth) (in).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Add 10–15% for waste.
What is an example of a tile Grout result?
With area 100, tile length 12, tile width 12, joint width 0.125 and tile thickness (joint depth) 0.375, the grout volume is 1.84 L.
Can I rely on this calculator for a decision?
Quantities are estimates. Add allowances for waste and site conditions, and follow local codes and a qualified professional's instructions for structural or safety-critical work. For this calculator in particular: Add 10–15% for waste.
Related calculators
- Tile Calculator — Number of tiles (and boxes) for an area.
- Cost to Tile a Shower Calculator — Estimated cost from tiled area, material price and labor price.
- Flooring Calculator — Flooring area with waste, and boxes if you know the coverage per box.
- Carpet Calculator — Square yards of broadloom carpet for a room, choosing the layout that wastes least.
- Roof Pitch Calculator — Roof pitch as rise per 12 inches, angle, slope percent and rafter length factor.
- Aquarium Volume Calculator — Capacity and filled weight of a rectangular aquarium.
Sources
- OpenStax, Prealgebra 2e (Rice University): perimeter, area, volume, circumference and the Pythagorean theorem
- NIST Special Publication 811, Guide for the Use of the International System of Units (SI), Appendix B conversion factors (international foot 0.3048 m, inch 25.4 mm, US gallon 3.785411784 L)
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.