Diameter is the number on the box; capacity is the number that decides whether a recipe fits. They diverge because depth is not proportional to width across a range, so a pan two sizes up can hold nearly twice as much rather than a quarter more. Weight matters as much in practice, because a large cast-iron casserole full of liquid is a two-handed lift out of an oven, and that is a real constraint rather than a footnote.
One honest observation about the published figures. Manufacturers list both quarts and litres, and the two do not always agree with each other: converting the quart figure gives a slightly different litre figure from the one printed beside it. The largest disagreement in this table is 16 cm, where the two published numbers differ by about 9.2%. Neither is wrong exactly, since they are rounded from different starting points, but it means a capacity quoted to two decimal places is false precision, and it is why the litre column below shows a single sensible figure.
| Diameter | Lid letter | Capacity | Weight | Serves |
|---|---|---|---|---|
| 14 cm | — | 0.9 L | 1.7 kg | 1 |
| 16 cm | A | 1.3 L | 2.7 kg | 1-2 |
| 18 cm | B | 1.8 L | 3.3 kg | 2 |
| 20 cm | C | 2.4 L | 3.5 kg | 2-3 |
| 22 cm | D | 3.3 L | 4 kg | 3-4 |
| 24 cm | E | 4.2 L | 4.3 kg | 3-4 |
| 26 cm | F | 5.3 L | 4.8 kg | 5-6 |
| 28 cm | G | 6.7 L | 5 kg | 7-8 |
| 30 cm | H | 8.5 L | 5.6 kg | 9+ |
| 34 cm | I | 12.5 L | 7.5 kg | 9+ |
The lid letter is the manufacturer's own code, and it is the useful one when buying a replacement lid: lids are sold by letter, not by centimetre. Capacities are the published figures reduced to one sensible litre value per size.
The French tool names, in plain English
French pastry recipes name tools precisely, and several of the names have no single English equivalent, which is why they survive untranslated in English-language pastry writing. A maryse is not simply a spatula: it is the flexible-bladed one you fold and scrape a bowl with, as opposed to a palette, which is a rigid blade for spreading. Using the wrong one is why a mousse loses air.
| French | English | What it is | Heat limit |
|---|---|---|---|
| maryse | rubber spatula, rubber scraper, silicone spatula, bowl scraper | A flexible spatula with a soft blade, used to fold, scrape a bowl clean and mix without knocking air out of a batter. | 220-260 °C |
| corne | bowl scraper, dough scraper, plastic scraper | A stiff handleless plate, usually one curved edge and one straight, for scraping dough out of a bowl and off a bench. Often confused with a maryse - the corne has no handle and does not flex the same way. | — |
| palette coudee | offset spatula, angled palette knife | A blade stepped down from the handle so the hand clears the work, for spreading and smoothing. | — |
| palette | palette knife, straight spatula | A long flat unstepped blade for spreading and lifting. | — |
| fouet | whisk, balloon whisk | Looped wires on a handle, for aerating and emulsifying. | — |
| cul-de-poule | mixing bowl, round-bottomed bowl | A hemispherical bowl - the round base leaves no corner a whisk or maryse cannot reach. | — |
| chinois | conical strainer, chinois | A fine cone-shaped strainer for passing creams and coulis to remove lumps and seeds. | — |
| corne a decor | comb scraper, decorating comb | A scraper with a toothed edge, for combing lines into cream or chocolate. | — |
| rouleau a patisserie | rolling pin | A cylinder for rolling dough to an even thickness. | — |
| pinceau | pastry brush | A brush for glazing, egg-washing and brushing off excess flour. | — |
Only one of these carries a meaningful heat rating: a silicone maryse is usable to roughly 220–260 °C depending on the make, which is why it is the one tool you can stir a hot caramel with. The rest are not heat tools.
What cast iron is actually for
The reason a cast-iron casserole is worth its weight is thermal mass. It takes a long time to heat and a long time to cool, which makes it poor at anything requiring a fast response and very good at everything requiring stability. A braise held at a low steady temperature for three hours, a bread baked in a preheated covered pot, a confit that must never boil: all of those are the same property. Asking it to sear quickly and then drop the heat is asking it to do the one thing its material prevents.
The serving figures in the table above are for a main course with the pan reasonably full, not filled to the rim. A casserole loaded to the brim boils over, and an enamelled one marks permanently where it does. Two thirds full is the practical maximum, which is part of why the useful capacity of a pan is always less than its published one.
Choosing between two sizes
When a recipe names a capacity and you own the sizes either side of it, go up rather than down for anything that rises or spatters, and down rather than up for anything braised. A braise wants the liquid to come well up the meat, and a pan too wide leaves it shallow and reduces it to nothing; a dough or a milk-based pudding wants headroom.
For baking specifically, the useful conversion is area rather than diameter. Going from 20 to 22 cm is a 21% increase in base area, so a batter poured to the same depth needs about a fifth more of everything and bakes in a similar time. Going from 20 to 24 cm is a 44% increase, which is a different recipe rather than a scaled one.
Questions about pans and tools
What is a maryse?
The flexible soft-bladed spatula used to fold, mix without knocking out air, and scrape a bowl clean. In silicone it takes roughly 220–260 °C depending on the make, which makes it the one spatula you can use in a hot pan.
Why do published capacities in quarts and litres not match?
Because each figure is rounded from a different starting point rather than converted from the other. The gap reaches several per cent on some sizes, so a capacity quoted to two decimals is false precision. Treat the litre figure as approximate and choose by serving count.
What does the letter on a casserole lid mean?
It is the manufacturer’s size code, and it is what replacement lids are sold by. If you need a lid, the letter is more useful than the diameter in centimetres.
My tin is 22 cm and the recipe says 20 cm. Does it matter?
Scale by area, not diameter. 20 to 22 cm is about 21% more base area, so the same batter spread to the same depth needs roughly a fifth more and bakes in a similar time. Jumping 20 to 24 cm is 44% more, which is enough to change the bake.
What is a cul-de-poule?
A hemispherical mixing bowl. The round base is the point: there is no corner a whisk or a maryse cannot reach, so nothing sits unmixed at the bottom.