How many calories are in cake?
A home-cut slice of iced chocolate cake, about 100 g, is roughly 400 kcal. A café slice of the same cake is 150–200 g and 550–800 kcal. “A slice” is the least standardised portion in this category, and on an iced cake the topping is often the bigger half.
Per portion
| Portion | Calories | Protein | Carbs | Fat |
|---|---|---|---|---|
| Plain sponge, no icing (60 g) | ~175 kcal | 3.5 g | 28 g | 5 g |
| Victoria sponge, jam and cream (80 g) | ~280 kcal | 3.5 g | 36 g | 13 g |
| Madeira or pound cake (70 g) | ~275 kcal | 3.5 g | 35 g | 14 g |
| Chocolate cake with buttercream (100 g) | ~400 kcal | 4 g | 50 g | 20 g |
| Carrot cake, cream cheese icing (120 g) | ~490 kcal | 5 g | 58 g | 27 g |
| Baked cheesecake (125 g) | ~420 kcal | 7 g | 38 g | 26 g |
| Fruit cake, marzipan and icing (60 g) | ~230 kcal | 2.5 g | 38 g | 7 g |
| Café slice, any of the above (175 g) | ~600–750 kcal | — | — | — |
What changes the number
Fat in the crumb. A fatless whisked sponge is about 290 kcal per 100 g. An equal weight of butter cake — Madeira, pound, most loaf cakes — is 390–400. Oil-based bakes — carrot, banana, chocolate — land near 400. Cheesecake is 320–350 per 100 g but cut in heavy slices, so it reads higher.
The filling. Jam is about 260 kcal per 100 g, whipped cream 50 kcal a tablespoon, and a buttercream layer costs the same as the icing on top, so two-layer cakes carry it twice.
How it was cut. A 20 cm round layer cake weighs about 1.2 kg: into eight, a slice is 150 g; into twelve, 100 g. Nobody tells you which, and bought slices sit at the top end: 150–200 g is normal, a layered slice up to 250 g. The whole cake is 4,000–5,000 kcal, about two days of maintenance calories.
Where it fits in a deficit
Cake is 300–450 kcal per 100 g with little water, no fibre and 4–7 g of protein a slice, so it sits well down the density ladder and does little for fullness. Cheesecake is the exception on protein; fruit cake scores low only because it is cut thin.
The practical issue is the unit it arrives in: someone else chose the size, and a 700 kcal café slice can be a third of a day’s intake. A smaller cut, a split slice, or 60 g of plain sponge with fruit at 200 kcal all leave you eating cake. Holding a calorie deficit does not require giving it up, only knowing that a slice is a range, not a number.
The icing is often the larger half
| Component | kcal / 100 g |
|---|---|
| Whisked sponge, no added fat | ~290 |
| Butter or oil cake crumb | ~390 |
| Cream cheese icing | ~390 |
| Glacé icing or fondant | ~390–410 |
| Buttercream | ~420–450 |
Icing is denser than nearly any crumb and makes up 25–40% of a finished cake’s weight. A 150 g slice carrying 50 g of buttercream holds about 215 kcal of icing against 390 kcal of cake — a third of the total, from the part a knife removes. On a thickly swirled cupcake, 40 g of sponge wears 40 g of buttercream and the icing genuinely is the larger half.
Scraping it off is the cheapest reduction available here: 150–250 kcal from a bought slice, cake intact. The same move as choosing a plain ring doughnut over a filled iced one, or a rich tea over a chocolate biscuit.
Figures are typical values and vary by variety, size and preparation. General information, not medical advice.