A gallon of milk weighs about 8.6 pounds (3.9 kg). A US gallon holds 3.785 liters, and cold milk has a density of roughly 1.03 g/mL, so a gallon of whole milk comes to about 8.62 lb, while skim milk is slightly heavier at about 8.65 lb. In short, milk weighs about 3% more than water.
Convert a Gallon of Milk’s Weight to Other Units
The converter starts at 8.6 pounds, the rounded weight of one gallon of milk. Type any weight and pick its unit. It then shows the same amount in kilograms, grams and ounces, so you can, for example, check a shipping limit or a recipe written in metric.
Milk is mostly water, so it makes sense that its weight sits close to the weight of water. However, milk also carries dissolved lactose, proteins and minerals, and those solids are denser than water. As a result, a jug of milk always weighs a little more than the same jug of water.
The math behind the number is simple. First, take the volume: the US gallon is exactly 231 cubic inches, or 3.785411784 liters (about 3.79 L on the NIST conversion card). Next, multiply by density. The University of Guelph dairy science text puts milk between 1.027 and 1.033 kg per liter at 20 C (68 F), and its table shows cold milk a bit denser than that. Finally, convert kilograms to pounds with the exact factor of 0.45359237 kg per pound.
Below you will find a chart by milk type, a size-by-size table, and a few surprises. For instance, the old idea that whole milk is the heaviest milk is backwards.
How Much a Gallon of Milk Weighs by Type
These figures use the density table from the Guelph dairy text and the exact size of the US gallon. The first column is fridge temperature, about 40 F (4.4 C); the second is room temperature.
| Milk type (fat) | Density, cold | Gallon weight, cold | Gallon weight at 68 F |
|---|---|---|---|
| Skim milk (about 0%) | 1.036 g/mL | 8.65 lb (3.92 kg) | 8.62 lb (3.91 kg) |
| Whole milk, homogenized (3.6%) | 1.033 g/mL | 8.62 lb (3.91 kg) | 8.59 lb (3.90 kg) |
| Raw farm milk (4%) | 1.035 g/mL | 8.64 lb (3.92 kg) | 8.60 lb (3.90 kg) |
| Half and half (12%) | 1.027 g/mL | 8.57 lb (3.89 kg) | 8.51 lb (3.86 kg) |
| Heavy cream (37%) | 1.008 g/mL | 8.41 lb (3.82 kg) | 8.30 lb (3.76 kg) |
| Water, for comparison | 1.000 g/mL | 8.35 lb (3.79 kg) | 8.33 lb (3.78 kg) |
The table has no separate row for 2% or 1% milk. Even so, their density falls between skim and whole, so a gallon of 2% milk weighs about 8.63 lb. In practice, every common milk lands within a few hundredths of 8.6 pounds.
Milk Weight by Container Size
Stores sell milk in more sizes than the gallon. So this chart scales the same cold whole-milk density (1.033 g/mL) to each US size. You can print it and tape it inside a cabinet door.
| Container | Volume | Weight (US) | Weight (metric) |
|---|---|---|---|
| 1 gallon | 128 fl oz (3.785 L) | 8.62 lb | 3.91 kg |
| 1/2 gallon | 64 fl oz (1.893 L) | 4.31 lb | 1.96 kg |
| 1 quart | 32 fl oz (946 mL) | 2.16 lb (34.5 oz) | 978 g |
| 1 liter | 33.8 fl oz (1,000 mL) | 2.28 lb | 1,033 g |
| 1 pint | 16 fl oz (473 mL) | 1.08 lb (17.2 oz) | 489 g |
| 1 cup | 8 fl oz (237 mL) | 8.6 oz | 244 g |
| 1 fluid ounce | 29.6 mL | 1.08 oz | 30.5 g |
| 5 gallons | 18.93 L | 43.1 lb | 19.6 kg |
If you need the volume side of this chart, our guide to how many quarts are in a gallon explains why 4 quarts, 8 pints and 16 cups make one gallon.
Recommended Tools for Weighing a Gallon of Milk
Most kitchen scales top out at 11 pounds, which comfortably covers a full gallon of milk. Therefore, look for a scale with a tare button and a capacity of at least 10 lb. In addition, a clear measuring cup with both mL and cup markings helps when you check smaller amounts by volume.
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Why a Gallon of Skim Milk Weighs More Than Whole
Many websites claim that whole milk is the heaviest milk because fat “adds weight”. The data says the opposite. Milk fat is lighter than water, which is why cream rises to the top of unhomogenized milk. Skim milk, by contrast, keeps nearly all of the dense solids (lactose, protein and minerals) but loses the light fat. As a result, a gallon of skim milk weighs slightly more than a gallon of whole milk.
The difference is tiny, though. At fridge temperature it is about 0.025 lb, or roughly 0.4 ounce per gallon. Cream shows the trend more clearly: heavy cream, at about 37% fat, weighs about a quarter pound less per gallon than skim milk.
| People often assume | What actually happens |
|---|---|
| More fat means heavier milk | More fat means lighter milk, because fat is less dense than water |
| Fluid ounces measure weight | Fluid ounces measure volume; 1 fl oz of milk weighs about 1.08 oz |
| A gallon is the same everywhere | A UK (imperial) gallon is 4.546 L, so it holds about 10.35 lb of milk |
Does Temperature Change the Weight of a Gallon of Milk?
Yes, but only if you keep the volume fixed. Warm milk expands, so a full gallon jug of warm milk holds slightly less milk than a full jug of cold milk. For example, whole milk at 102 F (38.9 C) has a density of about 1.022 g/mL, so a gallon at that temperature weighs about 8.53 lb. Meanwhile, the same gallon at 40 F weighs about 8.62 lb.
On the other hand, the weight of a given batch of milk never changes when it warms up. If you heat a pot of milk, it still weighs the same; it simply takes up more room. That is one reason dairies and cheesemakers often measure milk by weight instead of volume.
A Gallon of Milk vs a Gallon of Water
A gallon of water at room temperature weighs about 8.33 pounds. So a gallon of milk outweighs it by about a quarter pound, or about 3%. Water itself gets slightly lighter per gallon as it warms, just like milk; our article on how dense water is covers that curve in detail.
The comparison also gives you a handy shortcut. Because milk is about 3% denser than water, you can take any water weight and add 3%. For instance, a liter of water weighs about 1 kg, so a liter of milk weighs about 1.03 kg.
How to Weigh a Gallon of Milk at Home
- Clear the scale. Set a kitchen scale with at least a 10 lb capacity on a flat, hard counter.
- Weigh an empty jug. Note the weight of a clean, dry jug of the same brand and cap, or simply use the tare button.
- Place the full jug on the scale. Center it on the platform so it does not hang over the edge.
- Read the display in pounds or kilograms. Wait for the number to settle before you write it down.
- Subtract the container. Take away the empty jug weight to get the milk alone, about 8.6 lb for a full gallon.
- Check your result. Enter the number into the converter above to see it in kilograms, grams or ounces.
Do and Don’t When Measuring Milk
Do
- Use 8.6 lb per gallon as a reliable everyday figure.
- Weigh milk cold for numbers that match the charts.
- Tare out the jug or bowl before you weigh.
- Read liquid volumes at eye level on a clear cup.
Don’t
- Assume fluid ounces and weight ounces are equal for milk.
- Mix up US and UK gallons in older recipes.
- Expect whole milk to outweigh skim milk.
- Overload a small scale with several jugs at once.
Honest Limits of These Numbers
Every weight on this page comes from a density value multiplied by an exact volume. Real milk varies, however. Breed, season, feed and processing all shift its solids slightly, so two jugs can differ by a few hundredths of a pound. Also, jugs are not filled to the exact milliliter, and net-content rules allow small fill tolerances. In short, treat 8.6 lb as accurate to about one decimal place, and weigh the milk yourself when the second decimal matters.
Plant-based drinks are a separate case. Oat, almond and soy drinks have their own recipes and densities, so their gallon weight differs by brand. Similarly, flavored milks with added sugar run a little heavier than plain milk.
When Accuracy Really Matters
For a grocery list, 8.6 pounds is all you need. Still, a few jobs call for more care. Bakers who convert recipes from cups to grams should use about 244 g per US cup of cold whole milk. Next, anyone feeding calves or kids from bulk containers will find a scale faster than counting cups. Finally, if you ship milk or plan a cooler load, add the container weight and ice to the milk weight before you check a carrier limit.
Frequently Asked Questions
How much does a gallon of milk weigh in pounds?
A US gallon of milk weighs about 8.6 pounds. Cold whole milk comes to about 8.62 lb and cold skim milk to about 8.65 lb.
How much does a gallon of milk weigh in kilograms?
A gallon of milk weighs about 3.9 kilograms. Cold whole milk is about 3.91 kg and skim milk about 3.92 kg.
Is milk heavier than water?
Yes. Milk is about 3% denser than water, so a gallon of milk weighs roughly a quarter pound more than a gallon of water.
Does a gallon of whole milk weigh more than skim?
No. Skim milk is slightly heavier because milk fat is lighter than water. The difference is only about 0.4 ounce per gallon.
How much does half a gallon of milk weigh?
Half a gallon of whole milk weighs about 4.31 pounds, or about 1.96 kg.
How much does a cup of milk weigh?
A US cup of cold whole milk weighs about 244 grams, or about 8.6 ounces.
How many pounds is 5 gallons of milk?
Five gallons of whole milk weigh about 43.1 pounds, or about 19.6 kg, not counting the containers.
How much does a UK gallon of milk weigh?
An imperial gallon holds 4.546 liters, so it contains about 10.35 pounds (4.70 kg) of whole milk.
Does cold milk weigh more than warm milk?
Per gallon, yes, because cold milk is denser. However, a given batch of milk weighs the same at any temperature.
How much does the plastic jug add?
A plastic gallon jug and cap add only a few ounces. Weigh an empty jug of the same brand if you need the exact figure.
A Gallon of Milk: The Bottom Line
To sum up, a gallon of milk weighs about 8.6 pounds, or 3.9 kilograms. That comes from 3.785 liters times a density of about 1.03 g/mL, which makes milk roughly 3% heavier than water. Surprisingly, skim milk edges out whole milk, and cold milk edges out warm.
So for everyday use, 8.6 lb per gallon is the number to remember. When you need more precision, weigh the milk on a kitchen scale and run the result through the converter at the top of the page.
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