What is the standard custard ratio?

The standard custard ratio is 3 whole eggs per 600ml of milk, with 2-3 tablespoons of caster sugar and a teaspoon of vanilla extract. This produces a smooth, pourable custard with good body. For a richer custard, use 4 egg yolks per 600ml, or for a lighter version use 2 whole eggs. The ratio scales linearly — double the milk, double the eggs.

Should I use whole eggs or just yolks?

Whole eggs give a lighter custard that sets firmer — good for baked custards and custard tarts. Egg yolks alone produce a richer, silkier, more golden custard — perfect for creme anglaise and pouring custard. For a balanced approach, use a mix: 2 whole eggs plus 2 extra yolks per 600ml for the best of both worlds.

Why does my custard curdle?

Curdling happens when the eggs get too hot too quickly. To prevent this: temper the eggs by gradually adding hot milk to them while whisking (not the other way round), cook on a gentle heat stirring constantly, and never let it boil. If cooking on the hob, the custard is ready when it coats the back of a wooden spoon and a line drawn through it holds. Remove from heat immediately.

Can I make custard with cream instead of milk?

Yes, replacing some or all of the milk with single or double cream makes a richer custard. A common ratio for creme anglaise is 300ml milk and 300ml double cream with 6 egg yolks. For a baked custard, half-and-half milk and single cream works well. Pure cream custard is very rich and is typically reserved for creme brulee.

How do I thicken custard without cornflour?

Traditional custard thickens from the egg proteins coagulating when heated gently. More eggs will give a thicker custard. If you prefer using cornflour for reliability, add 1 tablespoon per 600ml of milk — this creates a more stable custard that is less likely to curdle and is closer to a creme patissiere in consistency.

BakeCalcs

Custard Ratio Calculator

Calculate egg, milk, and sugar quantities for custard based on volume and richness.

Custard Volume

Total finished custard volume

Richness

How We Calculate This

This calculator uses the classic custard ratio of 3 eggs per 600ml of milk as its baseline, scaling up or down linearly based on your desired volume. The richness setting adjusts the egg count: light uses 2 eggs, standard uses 3, and rich uses 4 per 600ml of liquid.

Sugar is adjusted proportionally, with lighter custards using less sugar to keep the flavour delicate. Vanilla is recommended at approximately 1 teaspoon per 600ml batch. All quantities scale proportionally when you change the volume.

Frequently Asked Questions

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Last updated: February 2026

All calculations are based on standard ratios and conversions. Results may vary with specific ingredients, equipment, and conditions.