Square Cake or Round?

Yes, by about a quarter, and the reason is geometry rather than generosity. A round cake is the circle that fits inside the square of the same width, and that circle covers roughly four-fifths of the square — so turning the same width from round to square adds about a quarter more cake at the same height. Those corners are real cake, and they are the portions people forget to count.

It follows that comparing a square cake with a round one by width alone is a mistake in both directions. A square is not a slightly different shape of the same cake, it is a bigger cake; and a round cake quoted at the same price as a square of the same width is the dearer of the two per slice. Compare portions, not inches.

Neither, once you compare honestly — a square simply moves you up the size ladder without changing the number on the tin. The price of a cake follows the quantity of cake and the hours of work in it, so a square that holds a quarter more is priced more like the next size up than like its round namesake. The table below prices the round sizes this kitchen quotes from, and each one gives its portion range.

Where shape genuinely changes value is in waste. A square cake cut on a grid yields rectangles that are all the same size, with nothing left over and no awkward last piece; a round cake cut into wedges gives you slices that are wide at the crust and nothing at the point, which is why caterers cut large rounds on a grid instead. If every portion must be equal and nothing may be left, square wins on arithmetic.

They are two names for one idea: a shallow rectangle of cake, baked flat in a large tin, finished on top and cut into squares. Sheet cake is the American term and the one most search results use; slab cake and tray bake are what British bakeries have always called it. The defining features are the single thickness and the flat top — it is a cake built to be cut up and handed round, not to stand in the middle of a table.

That shape is cheap per head for good reasons. One layer means no filling, stacking or levelling; a flat top means the icing is spread rather than smoothed and sharpened; and a rectangle travels in a box with no risk of a lean. It is the correct answer for a school fete, an office leaving party or anywhere that wants a hundred portions rather than a centrepiece — and the wrong answer for a cake anybody is going to photograph.

Because a corner is the hardest thing in the kitchen to finish. A round cake is smoothed by turning it against a straight edge, which produces a true side almost mechanically; a square has four vertical corners that must each be built up, chilled and pared square by hand, and any one of them that is soft or rounded is the first thing the eye lands on. Rolled icing is draped and sharpened instead, which is far more forgiving on an edge.

So the practical consequence runs the other way round from what most people expect: a square buttercream cake is more work than a square fondant one, and considerably more work than a round buttercream cake of the same size. If you want a square and you want buttercream, that is a conversation about hours rather than a shape preference, and the finishes page is where those hours are priced.

On a grid, not in wedges, and the method is worth knowing because it is the difference between the portion range a baker quotes and the number of people who actually get cake. Cut the round in half across the middle. Then cut each half into straight strips about a finger's width apart, and cut each strip across into portions of roughly the same width. What you get is a tray of neat rectangles and a few curved end pieces, all of them the same volume.

Wedges are for a cake at a table where the first slice is a ceremony — they are generous, they look right, and they feed perhaps half as many people as the same cake cut on a grid. Every portion figure on this site is the grid cut, which is why a modest-looking cake feeds more people than you would guess from looking at it. If you are cutting in wedges, order a size up.

Round, as the price list stands, plus hearts and numbers which are cut to shape and charged on top of the size price — the designs page lists what each shaping adds. A square is not on the list, which means it is a conversation rather than a refusal: the tins, the corners and the extra cake all have to be agreed before a price exists, so ask rather than assume either way.

If what you actually need is a great many equal portions, say that instead of naming a shape. The usual answer is a larger round cut on a grid, or a cake with cupcakes beside it, and both arrive at the number more cheaply than a bespoke square would. Delivery is quoted from £30 by distance, and a wide flat cake is the one shape where the drive genuinely matters.