What are pizza stones made of?

Cordierite

Cordierite is a magnesium iron aluminium silicate, made into stone by firing mineral powders at very high temperature. Its key property is very low thermal expansion: it barely changes size as it heats, so it resists the stress that cracks other ceramics. That is why kiln shelves and nearly all pizza oven stones are cordierite.

Cordierite stones are usually a pale sandy colour when new, slightly rough and porous. They handle the 450°C to 500°C of an outdoor pizza oven and are the best choice for a kitchen oven too.

Ceramic and clay

Some cheaper stones are general ceramic or terracotta-style clay. They work in a kitchen oven but are more prone to thermal shock, so they can crack if heated fast, put on a hot BBQ or splashed with water. Many have a lower maximum temperature, sometimes printed on the box.

Glazed ceramic stones look neat and wipe clean, but the glaze reduces the stone's ability to draw moisture from the dough, and some glazes have temperature limits. Check the maker's maximum before using one in a pizza oven.

Materials compared

General properties; check the maker's maximum temperature and care advice for any specific stone.

Are pizza stones safe?

Unglazed cordierite and food-grade ceramic are widely used for baking and are considered food safe. They are fired at temperatures far above anything a home or pizza oven reaches. Buy from a known brand or oven maker, and avoid stones with unknown glazes or coatings.

Darkening from use is carbonised flour and oil, not a sign of the stone breaking down. Do not use soap or chemical cleaners, which soak into the pores. See pizza stone smoking or turned black and how to clean a pizza stone.

Thickness and size

Kitchen oven stones are usually around 1 to 1.5 cm thick. Pizza oven stones are often thicker, about 1.5 to 2 cm, to store more heat. A thicker stone recovers better between pizzas but takes longer to preheat and weighs more.

Size depends on the oven. Leave a gap of a few centimetres around a stone in a kitchen oven for air to circulate. For a pizza oven, buy the replacement made for that model, as the size and thickness are matched to the burner. See why pizza stones crack if you need a replacement.

Stone or steel?

A pizza steel is a slab of plain steel, often 6 to 10 mm thick. Steel conducts heat much faster than stone, so it crisps a base quickly at kitchen oven temperatures. It will not crack, but it is heavy and needs a light coat of oil to prevent rust. In a 450°C pizza oven, a steel can burn the base, which is why ovens use stone.

Our pizza stone vs pizza steel article goes into the details, and are pizza stones worth it explains when either is worth buying.

Choosing for your oven

For a kitchen oven, a cordierite stone or a steel are both good. For a lidded BBQ, cordierite is the forgiving choice. For a pizza oven, the stone is already included; most models in our best outdoor pizza ovens and best 12 inch pizza ovens guides use cordierite, and some list stone thickness, such as the 12 mm stone in the Gino D'Acampo Vesuvio.

Indoor electric pizza ovens use cordierite or ceramic stones too; see best electric pizza ovens for indoors.

Note:Let any stone cool fully before handling. Never put water on a hot stone.

Frequently asked questions

Are pizza stones toxic? Plain cordierite and food-grade ceramic stones are not considered toxic. Avoid stones with unknown coatings.

What is the best material for a pizza stone? Cordierite, for its heat tolerance and resistance to cracking.

Can a pizza stone go in the dishwasher? No. Water and detergent soak in and can crack or taint it.

Is a ceramic pizza stone the same as cordierite? Cordierite is a type of ceramic, but not all ceramic stones are cordierite. Check the listing.