Grout Quantity Calculator

How many kilograms of grout a tiled area needs from the tile size, the joint width, the tile thickness and the area.

Grout is sold in 1 kg, 2.5 kg and 5 kg bags, and the bag you need is decided by the joint rather than by the floor area. A 300 by 300 millimetre tile with a 3 millimetre joint takes roughly 0.4 to 0.5 kilograms per square metre, so a 10 square metre floor is one 5 kg bag. Move to a 150 millimetre tile with a 5 millimetre joint and the same floor wants more than three times as much, because small tiles mean many more joints. This calculator works the volume of the joints out and converts it to powder.

At a glance

What you enter: Area to grout, Tile length, Tile width, Joint width, Tile thickness, Grout mixed density, Mixing and application allowance, Grout bag size, Price per bag
What you get: Grout per square metre, Grout for the area, Grout to mix, Bags to buy, Grout you will own, Cost of the grout, Square metres one bag covers, Mixed grout from one bag, Joints as a share of the tiled face
Formula shown: Yes, every step, right below your results.
Cost and privacy: Free, no account needed, and nothing you type is stored.

See worked examples ↓ Read the FAQ ↓ Share this calculator ↓

Area to grout sq m

The tiled area, not the room area. Count each wall or floor separately if the tiles differ.

Tile length mm

Standard sizes are 100, 150, 200, 300, 450, 600 and 900 mm square, plus 300 by 600 rectangles.

Tile width mm

Equal to the length for a square tile.

Joint width mm

Two to three millimetres for rectified porcelain, three to five for a ceramic with a rounded edge.

Tile thickness mm

The joint is filled to the full thickness of the tile, so this drives the volume directly. A 300 by 300 by 6 mm wall tile with a 3 mm joint uses about 0.4 kilograms per square metre.

Grout mixed density kg per litre

Cementitious grout mixed to a workable consistency is about 1.5 to 1.7 kilograms per litre. Use the figure on the bag if it gives one.

Mixing and application allowance %

Powder lost in the bucket, on the sponge and on the floor. Ten percent is a fair planning figure.

Grout bag size kg

Common sizes are 1 kg, 2.5 kg and 5 kg.

Price per bag

Optional. Used for the grout cost.

Reset

Results are estimates for general information only, always verify with a professional or official source before acting on them.

How to use the Grout Quantity Calculator

1 Enter Area to grout (sq m), The tiled area, not the room area. Count each wall or floor separately if the tiles differ.
2 Enter Tile length (mm), Standard sizes are 100, 150, 200, 300, 450, 600 and 900 mm square, plus 300 by 600 rectangles.
3 Enter Tile width (mm), Equal to the length for a square tile.
4 Enter Joint width (mm), Two to three millimetres for rectified porcelain, three to five for a ceramic with a rounded edge.
5 Enter Tile thickness (mm), The joint is filled to the full thickness of the tile, so this drives the volume directly. A 300 by 300 by 6 mm wall tile with a 3 mm joint uses about 0.4 kilograms per square metre.
6 Enter Grout mixed density (kg per litre), Cementitious grout mixed to a workable consistency is about 1.5 to 1.7 kilograms per litre. Use the figure on the bag if it gives one.
7 Enter Mixing and application allowance (%), Powder lost in the bucket, on the sponge and on the floor. Ten percent is a fair planning figure.
8 Enter Grout bag size (kg), Common sizes are 1 kg, 2.5 kg and 5 kg.
9 Enter Price per bag, Optional. Used for the grout cost.
10 Press Calculate. You get Grout per square metre, Grout for the area, Grout to mix, Bags to buy, Grout you will own, Cost of the grout, Square metres one bag covers, Mixed grout from one bag, Joints as a share of the tiled face, and every intermediate step stays visible under "How is this calculated?"
11 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.

Worked examples

Real numbers run through this calculator. Open any example to load it into the form above and change it.

A 10 square metre floor in 300 mm tiles

300 by 300 by 6 millimetre tiles with a 3 millimetre joint and a 5 kg bag.

You enter

Area to grout: 10 sq m
Tile length: 300 mm
Tile width: 300 mm
Joint width: 3 mm
Tile thickness: 6 mm
Grout mixed density: 1.60 kg per litre
Mixing and application allowance: 10%
Grout bag size: 5 kg
Price per bag: $12.00

You get

Grout per square metre: 0.38 kg
Grout for the area: 3.84 kg
Grout to mix: 4.22 kg
Bags to buy: 1
Grout you will own: 5.00 kg
Cost of the grout: $12.00
Square metres one bag covers: 13.02 sq m
Mixed grout from one bag: 3.13 L
Joints as a share of the tiled face: 0.0%

About 0.24 litres of joint per square metre, so 0.38 kilograms per square metre and 3.84 kilograms in total before waste. One 5 kg bag covers it with room to spare.

Open this example in the calculator →

A small format wall with wide joints

The same 10 square metres in 150 by 150 by 8 millimetre tiles with a 5 millimetre joint.

You enter

Area to grout: 10 sq m
Tile length: 150 mm
Tile width: 150 mm
Joint width: 5 mm
Tile thickness: 8 mm
Grout mixed density: 1.60 kg per litre
Mixing and application allowance: 10%
Grout bag size: 2.50 kg
Price per bag: $8.00

You get

Grout per square metre: 1.71 kg
Grout for the area: 17.07 kg
Grout to mix: 18.77 kg
Bags to buy: 8
Grout you will own: 20.00 kg
Cost of the grout: $64.00
Square metres one bag covers: 1.46 sq m
Mixed grout from one bag: 1.56 L
Joints as a share of the tiled face: 0.1%

The same area needs about 10.7 litres of joint, which is 17.07 kilograms, so eight 2.5 kg bags. Small tiles with wide joints are the expensive case for grout.

Open this example in the calculator →

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Frequently asked questions

How much grout do I need per square metre?

It depends on the tile size, the joint width and the tile thickness. A 300 by 300 by 8 millimetre tile with a 3 millimetre joint works out at about 0.43 kilograms per square metre, which matches the 0.4 to 0.5 kilograms the trade quotes. A 600 by 600 tile with the same joint uses about half that, because there is half as much joint per square metre. A 150 by 150 tile with a 5 millimetre joint uses more than three times as much.

Does tile thickness really change the grout quantity?

Yes, and in direct proportion. The joint is filled to the full thickness of the tile and then struck off level with the face, so an 8 millimetre joint depth holds twice the grout of a 4 millimetre one at the same joint width. A thick stone tile on a wide joint can use well over a kilogram per square metre, while a thin ceramic wall tile on a 2 millimetre joint uses a fraction of that. Enter the real thickness from the tile box rather than the nominal size.

How many square metres does a 5 kg bag of grout cover?

At 0.43 kilograms per square metre, which is a 300 by 300 by 8 millimetre tile with a 3 millimetre joint, a 5 kg bag covers about 11.7 square metres before the waste allowance, so about 10.6 square metres in practice. On a small tile with a 5 millimetre joint the same bag may cover only 4 square metres. Check the coverage table on the bag, because grout bulk density and the manufacturer mixing ratio both move the figure.

Should I add extra grout for waste?

Yes, about 10 percent. Powder is lost in the mixing bucket, on the sponge during the clean off, and on the floor when a joint is overfilled and struck back. Ten percent is a fair planning figure, and it also leaves a little for the joint that turns out deeper than expected. Buying a spare bag is cheaper than stopping a floor halfway across with a colour matched grout that has to be reordered.

Does this work for epoxy grout?

Only as a rough guide. Epoxy grout is mixed from two parts, has a much higher density than cementitious grout, and is usually sold in a kit rated for a specific area rather than by loose weight. The joint volume arithmetic is the same, so the litres per square metre figure here is still useful, but use the manufacturer coverage chart and their mixing instructions for the quantity and never adjust the ratio. Epoxy also sets hard, so mix only what you can apply within the stated working time.