How to Measure Gelato Overrun: The Weight-Cup Method
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Overrun is the percentage of air whipped into your mix during churning, and it is the single biggest reason two gelatos with identical recipes can feel completely different in the cup. The good news: you can measure it precisely with a scale and a cup, no lab required.
What Overrun Actually Measures
Quick reference. Overrun is the volume increase from incorporated air. A mix that doubles in volume has 100% overrun; gelato usually lands between 20% and 35%.
Overrun is defined as the percentage increase in volume of the finished frozen dessert compared to the volume of the liquid mix it was made from. All of that extra volume is air. When you freeze and churn a mix, the dasher whips air into it while ice crystals form, and the product expands. A mix that grows from 1 litre to 1.3 litres has gained 0.3 litres of air, or 30% overrun.
The distinction between gelato and industrial ice cream is largely a story about overrun. Traditional Italian gelato is churned slowly in batch freezers and carries roughly 20 to 35% overrun, while mass-market American ice cream is often run at 50 to 100% overrun, and economy brands can approach the legal ceiling. In the United States, federal standards of identity require ice cream to weigh at least 4.5 pounds per gallon, which effectively caps overrun near 100 to 120% (21 CFR 135.110). Less air per scoop is why gelato tastes more intense: flavor compounds are more concentrated when air is not diluting the base.
The Weight Method, Step by Step
The most reliable way to measure overrun in a small shop is the weight method, because weighing the same fixed volume of mix and of finished gelato removes any need to measure air directly. You compare how much a container of liquid mix weighs against how much the identical container of frozen gelato weighs, and the difference tells you how much air displaced the mass.
Take any rigid container you can fill level, such as a small metal cup or a portion tub. First weigh it empty and record the tare. Fill it to the brim with your liquid mix, level the top, and weigh it. Subtract the tare to get the weight of mix. Then, immediately after extraction, fill the exact same container to the brim with finished gelato, packing it without leaving voids, level it, and weigh it. Subtract the tare again to get the weight of gelato.
The Formula
Because the container holds a constant volume, the weight lost is entirely due to air. The overrun percentage is calculated from the two weights:
| Step | What you record | Example |
|---|---|---|
| Weight of mix in the cup | grams of liquid mix | 250 g |
| Weight of gelato in the cup | grams of frozen gelato | 195 g |
| Overrun | (mix minus gelato) divided by gelato times 100 | 28.2% |
In formula form, overrun % = (weight of mix minus weight of gelato) divided by weight of gelato, times 100. Using the numbers above, (250 minus 195) divided by 195 times 100 gives roughly 28%, which sits comfortably in the artisan gelato range. If your two weights come out nearly equal, you have very little air and a heavy, hard product; if the gelato weighs far less than the mix, you have whipped in more air than most Italian styles intend.
Why Your Numbers Drift
Even with a careful method, measured overrun moves with production conditions, so it helps to know what pushes it up or down. Draw temperature matters most: gelato extracted colder and stiffer holds the air you have built and reads higher, while a soft, warm draw tends to lose structure. Batch freezers with sharp, well-adjusted dashers whip more air than dull ones, and a fuller machine barrel generally incorporates less air than a partly filled one.
Recipe composition also sets a ceiling. Higher fat and higher total solids stabilize the air cells and support more overrun, while lean sorbet bases and very high sugar loads resist holding air and read lower. This is why the same batch freezer can give 25% on a sorbetto and 35% on a rich custard base without any change in technique.
Targets Worth Aiming For
For most gelaterie, a practical window is 20 to 35% overrun. Below about 20%, gelato becomes so dense that it eats cold and hard and can feel gummy; above roughly 40%, it drifts toward the airy, less intense character of commercial ice cream and loses the selling point of the category. Sorbetto usually sits a little lower than dairy gelato because it lacks fat to stabilize air. The right number is ultimately the one that gives your specific recipe the body and scoopability you want, measured consistently with the same cup every time so you can compare batches honestly.
A Volume Cross-Check
If you want to confirm the weight result, you can measure overrun by volume instead. Pour a known volume of mix, say exactly 1 litre, into the machine, and after extraction measure the volume of gelato it produced. Overrun % = (volume of gelato minus volume of mix) divided by volume of mix, times 100. The weight method is usually easier in a busy shop because scales are more precise and faster than measuring the volume of a stiff, aerated product, but running both once in a while is a good sanity check that your cup and your technique are giving consistent numbers.
Keep a simple log. Record the date, the flavour, the draw temperature, and the measured overrun for each batch. Over a few weeks this log turns overrun from a mysterious variable into a dial you can adjust deliberately, and it makes troubleshooting a hard or gummy batch far quicker because you can see immediately whether the air content moved or something else did.
Common Mistakes That Skew the Reading
The most frequent error is not filling both the mix cup and the gelato cup to the exact same level. Any air gap in the gelato cup, or any overpacking of the mix, throws the ratio off and can swing your reading by several points. Pack the gelato firmly to eliminate voids, but do not compress it so hard that you crush the structure you are trying to measure. Level both fills with a straight edge across the rim.
The second common mistake is measuring too late. Overrun should be read at extraction, straight from the batch freezer, because the product changes as it sits and hardens in the blast freezer. If you scoop from a display case that has been serving all day, you are measuring a partially collapsed, partially re-frozen product, not the overrun your machine actually produced.
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