# How much grout do I need?

Computes how much tile grout to buy, in pounds, kilograms and bags, from the tiled area, tile size, joint width and depth, the grout’s density and a waste allowance.

- Page: https://www.acalculator.org/construction/grout-calculator
- JSON spec: https://www.acalculator.org/construction/grout-calculator.json
- Version: 86803e6d427d

## Default answer

Example with the default inputs (Area to grout 100 ft², Tile length 12 in, Tile width 12 in, Joint width 0.125 in, Joint depth 0.375 in, Grout density 99.8847369218314 lb/ft³, Extra for waste 10%, Bag size 25 lb): Buy 7.2 lb of grout; bags to buy: 1.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| area | Area to grout | The tiled floor or wall area. |
| tl | Tile length | The long side of one tile. |
| tw | Tile width | The short side of one tile. |
| joint | Joint width | The gap between tiles: the spacer size. |
| depth | Joint depth | How deep the grout goes: usually the tile thickness. |
| density | Grout density | Pounds of grout powder that fill one cubic foot of joint. Check your grout’s coverage chart. |
| waste | Extra for waste | Extra grout for mixing, spills and clean-up; LATICRETE’s rule is at least 10%. |
| bag | Bag size | The weight of one bag of grout. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| pounds | Grout (lb) | The grout powder to buy, in pounds, with the waste allowance. |
| kilograms | Grout (kg) | The same weight in kilograms. |
| bags | Bags to buy | The weight ÷ the bag size, rounded up. |
| liters | Joint volume (L) | The volume of all the joints, with the waste allowance, in litres. |
| perArea | Grout per 100 ft² (lb) | Pounds of grout for each 100 square feet, without waste. |
| perM2 | Grout per m² (kg) | Kilograms of grout for each square metre, without waste. |

## Method

Grout volume = area × (L + W) ÷ (L × W) × joint width × joint depth × (1 + waste ÷ 100); weight = volume × density; bags = weight ÷ bag size, rounded up.

## Assumptions

- Square-edged tiles laid in a grid, every joint the same width, filled to the joint depth (usually the tile thickness).
- The density is how much grout powder fills a unit of joint volume. 1.6 kg/L (about 100 lb/ft³) is a typical cement grout figure; for the best estimate use the coverage chart or data sheet of your grout.
- Waste is 10% by default, LATICRETE’s “10% rule”.
- Bags are 25 lb (11.3 kg) by default, a common size for cement grout.

## Worked examples

1. area = 9.290304, tl = 0.3048, tw = 0.3048, joint = 0.003175, depth = 0.009525, density = 1,600, waste = 0%, bag = 11.339809 gives liters = 1.843545, kilograms = 2.949672, pounds = 6.502913, perArea = 6.502913, bags = 1. Source: Mapei group (Adesital), Grouts calculator (consumption from the volume to fill and the product density; inputs tile length, width, thickness and joint width). https://cms.mapei.com/adesital/en/product-calculator/grouts-calculator/.
2. area = 10, tl = 0.3, tw = 0.6, joint = 0.003, depth = 0.01, density = 1,600, waste = 10%, bag = 5 gives perM2 = 0.24, kilograms = 2.64, liters = 1.65, bags = 1. Source: LATICRETE, Mastering Grout Calculation: The Power of the Grout Calculator (add at least 10% for waste). https://www.laticrete.com/blog/2023/october/the-power-of-the-grout-calculator.
3. area = 37.161216, tl = 0.0508, tw = 0.0508, joint = 0.003175, depth = 0.00635, density = 1,601.846337, waste = 10%, bag = 11.339809 gives pounds = 114.583333, bags = 5. Source: LATICRETE, Cement Grouts FAQ (25 lb bags of sanded and unsanded grout). https://www.laticrete.com/support-and-training/downloads-and-faq/faqs/planning-a-job/cement-grouts.

## FAQ

### How do I calculate how much grout I need?

Each tile owns one length and one width of joint, so the joint volume per area is (L + W) ÷ (L × W) × joint width × joint depth. Multiply by the area and by the grout’s density to get the weight. For 100 ft² of 12 × 12 in tile with 1/8 in joints 3/8 in deep, that is 112.5 in³ of joint, about 6.5 lb of grout.

### How does the Mapei grout calculator work out consumption?

The Mapei group’s grout calculator works from the volume to fill (tile length, width and thickness, joint width and area) and the product’s density. This page uses the same geometry; type the density from your grout’s data sheet for the closest match.

### Why do small tiles need more grout?

Small tiles have more joint per square foot. A 2 × 2 in mosaic has 12 times the joint length of a 24 × 24 in tile over the same area, so with the same joints it needs 12 times the grout.

### How much extra grout should I buy?

LATICRETE’s rule is to add at least 10% for waste during mixing and clean-up. The calculator adds 10% by default; then it rounds the bags up.

### How deep is a grout joint?

Usually the full thickness of the tile, less any thinset that squeezed up into the joint. Use the tile thickness unless you know the joints are shallower.

### What density should I use for grout?

The page uses 1.6 kg/L (about 100 lb/ft³), a typical figure for cement grout powder per volume of joint. Grouts differ: epoxy and lightweight grouts are lighter. Use the coverage chart or data sheet of the grout you buy.

## Sources

- Mapei group (Adesital), Grouts calculator (consumption from the volume to fill and the product density; inputs tile length, width and thickness, joint width and area; results are estimates). https://cms.mapei.com/adesital/en/product-calculator/grouts-calculator/ (retrieved 2026-10-01)
- LATICRETE, Mastering Grout Calculation: The Power of the Grout Calculator (tile size, joint width and depth, and area; add at least 10% for waste). https://www.laticrete.com/blog/2023/october/the-power-of-the-grout-calculator (retrieved 2026-10-01)
- LATICRETE, Cement Grouts FAQ (grout coverage is approximate; 25 lb (11.3 kg) bags). https://www.laticrete.com/support-and-training/downloads-and-faq/faqs/planning-a-job/cement-grouts (retrieved 2026-10-01)
- NIST Handbook 44 (2026), Appendix C, General Tables of Units of Measurement: 1 in = 2.54 cm; 1 lb = 0.45359237 kg; 1 ft³ = 0.028316846592 m³. https://www.nist.gov/document/2026-nist-handbook-44-appendix-c (retrieved 2026-10-01)