Surfaces calculator

Grout Calculator

Estimate grout coverage from tile dimensions, thickness, and joint width. Switch between US customary and metric units, adjust the assumptions, and keep every step visible.

01 Measure02 Allow03 Order

Project inputs

Use one unit system throughout. Defaults show a realistic example; replace them with measurements from your project.

Unit system

Tiled areaExample input — replace with your project value.ft²Tile lengthPlanning default — verify the selected product or project specification.inTile widthPlanning default — verify the selected product or project specification.inTile thicknessPlanning default — verify the selected product or project specification.inJoint widthPlanning default — verify the selected product or project specification.inMixed grout densityPlanning default — verify the selected product or project specification.lb/ft³Waste allowanceAdd for cuts, breakage, spillage, and uneven site conditions.%

Measure the finished shape. This is a geometric estimate. Tile profile, joint depth, application loss, and product formulation matter; compare the result with the manufacturer’s coverage chart.

Estimate matches the inputs shown.

ReviewedNovember 2, 2026

ByBuildGauge Editorial Team

ScopeFormula, defaults & sources

Report an issue ↗

The calculation

A visible formula, not a black box.

Weight · Mathematical derivationgrout volume ≈ area × joint width × tile thickness × (1/tile length + 1/tile width)

Inputs are converted to a common base unit before calculation. Purchase quantities are rounded only at the final buying boundary.

Example inputDefaultStatus

Tiled area120 ft²Replace with measurement

Tile length12 inPlanning default — verify

Tile width12 inPlanning default — verify

Tile thickness0.375 inPlanning default — verify

Joint width0.125 inPlanning default — verify

Mixed grout density100 lb/ft³Planning default — verify

Waste allowance10 %Planning default — verify

Worked example

Example: 120 ft² of 12 in tile

Using 3/8 in tile, 1/8 in joints, and the editable density default gives a geometric weight estimate that must be checked against the grout chart.

Use this to understand the workflow—not as a recommendation for your project.

Sources & scope

What supports this calculation.

Manufacturer dataMAPEI Kerapoxy coverage chart ↗

Coverage depends on tile length, width, thickness, and joint width; the calculator's density remains an editable planning value.

Mathematical derivationNIST SI conversion factors ↗

Exact length, area, and volume unit conversions; the project formula is derived from standard geometry.

Common mistakes

Check the job, not just the number.

01Leaving the example grout inputs unchanged instead of entering measured project values.
02Treating an editable coverage, size, density, or allowance as universal instead of checking the selected product label, project documents, and local requirements.
03Ordering from the rounded result without reviewing exclusions: This is a geometric estimate. Tile profile, joint depth, application loss, and product formulation matter; compare the result with the manufacturer’s coverage chart.

Questions, answered

Grout FAQ

What does the Grout Calculator estimate?

Estimate grout coverage from tile dimensions, thickness, and joint width. The primary output is weight, with the intermediate assumptions kept visible.

How is the grout result calculated?

The visible formula is: grout volume ≈ area × joint width × tile thickness × (1/tile length + 1/tile width). Inputs are converted to a common base unit before the final purchase boundary is rounded.

Are the default values recommendations?

No. Dimensions are worked examples and product-dependent presets are planning defaults. Replace them with the selected product label, project documents, and local requirements.

Is the result ready to order from?

Use it as a checked planning estimate, then confirm packaging, minimum orders, installation instructions, site conditions, and any code or professional-design requirements.