A milk frother does up to three different jobs: it warms milk, it whips air into it, and (on some models) it does the second one cold. The first question is not "which brand?" but how much milk do you froth at once, and for which drink? Get that wrong and you end up either with a jug that overflows or a machine you run three times for one family breakfast.
Whisking air into milk makes it grow. A jug that can heat 300 ml of milk may only be able to froth a smaller amount, because the foam needs headroom. Most frothers mark two lines inside the jug: a max-heat line and a lower max-froth line. The one that matters for a cappuccino is the lower one.
Some real examples of the range: a small single-serve frother handles about 120 ml for both heating and frothing. A mid-size jug heats about 300 ml, with a froth line often near half of that. A large induction jug heats up to about 600 ml, but froths only about 250 ml. Always read the froth line on the one you are considering.
Pick a drink and how many cups you make in one go. The jug below shows how much milk you need and whether the job is a froth job or a heat job. Then it tells you how many rounds a jug of each size would need.
240 ml
Froth job: milk grows as air goes in
| Jug size | Limit | Rounds |
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Milk's natural sugar, lactose, tastes sweeter when it is warm, which is why a good latte needs no sugar. Aim for roughly 60–65°C. Much hotter than that and the milk starts to taste cooked and flat, and the foam goes thin. Most electric frothers stop on their own at a fixed temperature, which is one reason people who are new to milk drinks find them easier than a steam wand.
The jug you need is set by your biggest batch, not your usual one.
Handheld whisk. A small battery wand you put into a mug of warm milk. It is the cheapest option and makes decent cold foam, but you heat the milk yourself.
Electric jug with a whisk. You pour in milk and press a button. It heats and froths, and many stop at a set temperature. This is what the picks below are. They suit one to four cups a day and need a rinse afterwards.
Steam wand on an espresso machine. The most control and the best texture, but it takes practice. If you already own a machine with a wand, a jug frother is only useful for cold foam or for making milk away from the machine.
Whole milk gives a thicker, sweeter foam than skimmed. Plant milks vary: oat versions made for baristas froth well, others turn thin. Cold milk straight from the fridge froths best for cold foam. A drink with coffee in it also has caffeine, so if you make several in a row, think about who is drinking them.