Making Chai for Eight Is Not the Same Job as Making It for Two

Treat the sections below as a sequence. With scaling a pan of chai up for a crowd, getting the early decisions right makes the later ones much easier.

Why the arithmetic breaks

Doubling the volume in a pan does not double the surface area exposed to either the flame or the air above it. The larger batch therefore takes longer to reach a boil and loses proportionally less liquid once it gets there.

A recipe calibrated for two glasses comes out weaker and milkier when you simply multiply everything by four. Extraction is also skewed, because the leaf sits in liquid that spent much longer climbing to temperature. The net result is a cup that is both under-extracted and over-diluted, which the drinker reads simply as weak.

Adjusting the leaf

Raise the leaf by roughly ten per cent above the linear multiple to compensate for the reduced evaporation. Add it once the water is at a genuine boil rather than from cold, so the long heat-up does not stew it. Watch the colour instead of the clock, because timings learned on a small pan do not transfer to a large one.

A deeper layer of liquid means the leaf can sit as a raft on the surface, so stir once to break it up. Judge the decoction before the milk goes in and an under-strength batch is still entirely fixable.

Adjusting the spice

Aromatic spice scales sub-linearly because perceived intensity does not rise in proportion to concentration. Multiplying a four-gram dose by four gives sixteen grams, and most people find twelve to fourteen better.

The ratio does the work here: cloves and star anise in particular become dominant in large batches in a way they never do in small ones. Ginger scales more honestly than the aromatics, so keep the ginger linear and trim the rest if in doubt. Taste the decoction before the milk arrives, since spice is far easier to read without dairy in the way.

Heat management

A large pan on a small burner heats unevenly and scorches milk in a ring directly above the flame. Use the biggest burner you have and a pan whose base genuinely matches it rather than overhanging by inches. Stir along the bottom every minute or so once the milk is in, which is unnecessary at two-glass volumes.

Over the flame, a heavy base earns its price here in a way it simply does not for a small everyday pot.

If the pan is much wider than the burner, accept that you will be stirring more or less continuously.

The holding problem

Chai held hot keeps cooking, so a large pan made in advance is a materially different drink twenty minutes later. Straining the whole batch into a pre-warmed flask stops the extraction while keeping most of the heat.

A flask also solves the pouring problem, because nobody enjoys lifting a full four-litre pan repeatedly. If you must hold it in the pan, take it off the heat entirely rather than leaving it at a low simmer. Sugar in a held pan accelerates the caramelising, which is another argument for sweetening in the glass.

Milk fat, water hardness and hob power shift the result more than the recipe admits.

The two-round strategy

For groups above about six, two consecutive pans beat one large pan on very nearly every measure. The second pan starts while the first is being drunk, so nobody waits and nothing sits around getting darker. It also lets you adjust the second batch after hearing what people thought of the first one.

The only real cost is another five minutes at the hob, which is generally where the conversation already is. Scaling up is a compromise, whereas scaling out across time usually is not.

The takeaway

When the group grows, add another pan rather than a bigger one.

Measure it properly once, then never measure it again.