Overrun: how much air is in ice cream
Overrun tells you how much the ice cream has grown in volume compared with the mix. How it is calculated, why gelato has less air than industrial ice cream and what a home machine can manage.
As the mix freezes in an ice cream maker, the paddle whips it at the same time and works air into it. That’s why ice cream has a larger volume than the mix it was made from. How much it has grown is expressed as overrun. It’s one of the numbers that most distinguishes cheap ice cream from premium, and gelato from cream ice cream.
Why we need air
Without air, ice cream would be as hard as an ice cube. Air bubbles make ice cream lighter and finer and make it scoopable. According to Douglas Goff (University of Guelph), 1 g of typical ice cream contains about 8 million air bubbles around 70 µm in diameter. The smaller and more even the bubbles, the creamier the ice cream.
The bubbles are held in place by a network of partly joined fat globules and by proteins — much as in whipped cream. That’s why well-aged mixes with enough fat and protein take up air better. More in the article What fat, sugar, protein and air do in ice cream.
How overrun is calculated
By volume:
overrun (%) = (volume of ice cream − volume of mix) / volume of mix × 100
If 1 litre of mix makes 1.5 litres of ice cream, the overrun is 50 %. At 100 % overrun, half the volume of the ice cream is air.
By weight (practical — kitchen scales are all you need):
overrun (%) = (weight of mix − weight of the same volume of ice cream) / weight of ice cream × 100
Goff gives an example: a litre of ice cream weighs 560 g and a litre of mix 1,090 g. The overrun is (1,090 − 560) / 560 × 100 ≈ 95 %.
Tip
Measure the overrun at home. Fill a mug with mix and weigh it, then fill the same mug with finished ice cream from the machine (without gaps) and weigh it again. If the mix weighs 272 g and the ice cream 200 g, the overrun is (272 − 200) / 200 × 100 = 36 %.
Ice cream mix has a density of about 1.09–1.1 kg per litre, so it’s slightly heavier than water.
How much air each type has
| Type | Overrun | Source |
|---|---|---|
| Economy industrial ice cream | around 120 % | Goff |
| Standard industrial | 100–120 % | Goff |
| Premium | 60–90 % | Goff |
| Super-premium | 25–50 % | Goff |
| Gelato | 20–35 % (artisan at most 35–40 %) | Wikipedia (EN, IT) |
| Frozen custard | 15–30 % | Wikipedia |
| Sherbet | at most about 55–60 % | calculated from US law |
| Granita, rolled ice cream | almost none | not whipped |
Italian sources give an overrun of 70–130 % for industrial gelato. Artisan gelato has less air, which is why it’s denser and its flavour more intense.
What the law says
The US regulation 21 CFR § 135.110 doesn’t limit overrun directly, but it specifies that a gallon of ice cream must weigh at least 4.5 pounds (about 0.54 kg per litre). With a typical mix density, this works out at a maximum overrun of about 100 % (our own calculation). For sherbet, the minimum weight is 6 pounds per gallon, which allows less air.
We found no limit on overrun or minimum weight for ice cream in either Slovak or Czech legislation — they mainly set minimum composition. When buying packaged ice cream it’s therefore worth comparing the price per kilogram, not just per litre: a litre of cheap ice cream can be half air.
Home machines
Home ice cream makers work less air into the mix than industrial continuous freezers. Homemade ice cream therefore usually has an overrun closer to super-premium ice cream or gelato. zmrzka’s target ranges take this into account — for example 25–60 % for cream ice cream. Details on the individual machines can be found in the Machines section.
- In a compressor ice cream maker and a freezer-bowl ice cream maker, the paddle whips the mix while it freezes.
- The Ninja CREAMi first freezes the mix into a block and then shaves it — the principle is different.
- With the no-machine method, air gets into the ice cream via whipped cream (no-churn) or by stirring.
Too much and too little air
Goff describes typical defects related to air:
- too much air — foamy, crumbly, “snowy” ice cream with a weak body that melts quickly,
- too little air — dense, heavy ice cream, even gummy if there’s excess stabiliser,
- shrinkage — the ice cream pulls away from the sides of the container; it’s linked to high overrun and temperature swings.
Churning too long in the machine can make the fat clump into butter granules. Take the ice cream out when it holds its shape and has the consistency of soft-serve.
Did you know?
Density of finished ice cream = density of mix / (overrun / 100 + 1). A litre of ice cream with 30 % overrun, made from a mix with a density of 1.1 kg/l, weighs about 850 g; at 100 % overrun only 550 g.
So overrun is neither a defect nor a trick — it’s part of the recipe. It decides whether the ice cream will be light and airy, or dense and intense like fior di latte or frozen custard.
Recipes for this article
Egg-free vanilla ice cream (Philadelphia style)
Pure, creamy vanilla with no egg yolks — fresh, milky and ready without cooking a custard.
Fior di latte
The purest gelato of all: milk, a little cream and sugar. No eggs, no vanilla — it tastes of fresh, sweet milk.
Vanilla frozen custard
Thick, silky vanilla custard with six egg yolks and very little air — a classic of the American Midwest.
Sources
More articles
Using eggs safely in homemade ice cream
Why raw yolks don’t belong in ice cream, why 71 °C is enough for safety while 82 °C is the cook’s upper limit for custard, and when to reach for pasteurised eggs.
Storing ice cream and what to do when it melts
What temperature to store ice cream at, how long homemade and shop-bought ice cream keeps, and why melted ice cream shouldn’t be refrozen.
Keeping your ice cream maker and kitchen clean
Once the mix has been cooked, hygiene is your only protection against bacteria. How to clean the ice cream maker, the bowl and your utensils, and why leftovers should never go back in.
Listeria and ice cream: who should be careful
Listeria survives freezing, and a small dose is enough to make vulnerable people ill. What outbreaks in the US and the UK showed, and who should take more care with ice cream.
Liquid nitrogen ice cream: why not at home
Nitrogen ice cream looks spectacular, but liquid nitrogen belongs in the hands of professionals. What the risks are and what to watch out for when you buy it.
How zmrzka calculates the composition of the mix
Fat, milk solids, sugars, total solids, PAC, POD and Brix: where the numbers on every recipe come from, which databases the ingredients are taken from and where the calculation reaches its limits.