Grout Calculator

Estimate tile grout from tile size, tile thickness, joint width and area: joint volume, grout weight at your product’s density, and whole packs with waste.

Interactive calculator · Method GROUT-QUANTITY-1.0 · Last reviewed: 2026-11-04

Calculate your scenario

Joint volume per unit of tiled area = (tile length + tile width) ÷ (tile length × tile width) × joint width × tile thickness.

Your inputs

Try an example

Units

Tile length (in or mm)

Tile width (in or mm)

Tile thickness (joint depth) (in or mm)

Joint width (in or mm)

Tiled area (sq ft or m²)

Waste allowance (%)

Density unit

Product density from the bag or data sheet (example 1.8 kg/L) (kg/L or lb/ft³)

Pack size unit

Pack size (lb or kg)

Default worked example. Edit the inputs to calculate your scenario.

Default worked example

Whole packs 1 × 25 lb

Grout weight 3.65 kg (8.05 lb)

Joint volume with waste 2.028 L (123.8 cu in)

Joint volume per unit area 1.125 cu in per sq ft

(12 + 12) ÷ (12 × 12) × 0.125 × 0.375 × 100 sq ft × (1 + 10%) = 2.028 L × 1.8 kg/L = 3.65 kg.

How to use the calculator

Choose inches or millimeters, enter the tile size, tile thickness, joint width and the area to grout, then the density from your product’s data sheet and its pack size.

What the result means

Grouting 100 sq ft of 12 × 12 in tile, 3/8 in thick, with 1/8 in joints takes about 2.03 L of joint volume with 10% waste, or about 3.65 kg (8.05 lb) at 1.8 kg/L: one 25 lb pack.

Formula and units

Joint volume per unit of tiled area = (tile length + tile width) ÷ (tile length × tile width) × joint width × tile thickness. Multiply by the area (sq ft × 144 for inches; m² × 1,000,000 for millimeters), add waste, convert to liters (1 cu in = 0.016387064 L), then multiply by the product density to get weight. Packs = weight ÷ pack size, rounded up.

Worked examples

100 sq ft of 12 × 12 in tile, 1/8 in joints: Tile length: 12 in or mm; Tile width: 12 in or mm; Tile thickness (joint depth): 0.375 in or mm; Joint width: 0.125 in or mm; Tiled area: 100 sq ft or m²; Waste allowance: 10 %; Product density from the bag or data sheet (example 1.8 kg/L): 1.8 kg/L or lb/ft³; Pack size: 25 lb or kg; Units: in; Density unit: kgL; Pack size unit: lb.
Example result: Whole packs: 1 × 25 lb; Grout weight: 3.65 kg (8.05 lb); Joint volume with waste: 2.028 L (123.8 cu in); Joint volume per unit area: 1.125 cu in per sq ft.

20 m² of 600 × 300 mm tile, 3 mm joints: Tile length: 600 in or mm; Tile width: 300 in or mm; Tile thickness (joint depth): 10 in or mm; Joint width: 3 in or mm; Tiled area: 20 sq ft or m²; Waste allowance: 10 %; Product density from the bag or data sheet (example 1.8 kg/L): 1.6 kg/L or lb/ft³; Pack size: 5 lb or kg; Units: mm; Density unit: kgL; Pack size unit: kg.
Example result: Whole packs: 2 × 5 kg; Grout weight: 5.28 kg (11.64 lb); Joint volume with waste: 3.3 L (201.4 cu in); Joint volume per unit area: 0.15 L per m².

Limitations and common mistakes

Density and yield are product-specific; the 1.8 kg/L default is an example, so use the figure on your grout’s bag or data sheet (1 kg/L = 62.43 lb/ft³). This sizes grout for the joints only; thinset or mortar under the tile is a separate product with its own coverage. It assumes square-edged tiles with full-depth joints; pillowed edges and shallow joints use less.

Using the same quantity for small mosaics as for large tiles: more joints per square foot means far more grout for the same area.

Sources and assumptions

Method GROUT-QUANTITY-1.0; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.