✔ Updated · USDA weights for whole, 2%, skim + every carton size
That gallon jug always feels heavier than it looks on the walk in from the car, and now I know exactly why. Here’s the real weight for every kind of milk and every carton size.
A US gallon of whole milk weighs about 8.6 pounds (3.9 kg), using the USDA’s conversion factor of 8.60 lb per gallon. Reduced-fat 2% and 1% milk weigh 8.62 lb and skim weighs 8.63 lb, a hair heavier because milk fat is lighter than water. A gallon of water weighs about 8.34 lb, so milk is roughly 3% heavier. Add a few ounces for the jug.
- Whole milk: 8.60 lb (3.90 kg) per gallon
- 2% and 1% milk: 8.62 lb (3.91 kg)
- Skim milk: 8.63 lb (3.91 kg)
- Half gallon of whole milk: 4.3 lb (1.95 kg)
Milk Weight by Type
These are the US Department of Agriculture’s official pounds-per-gallon factors for fluid milk, from the USDA Agricultural Marketing Service conversion table. I’ve added kilograms so you don’t have to do the math.
| Milk (1 US gallon) | Pounds | Kilograms |
|---|---|---|
| Whole milk | 8.60 lb | 3.90 kg |
| Reduced-fat 2% milk | 8.62 lb | 3.91 kg |
| Low-fat 1% milk | 8.62 lb | 3.91 kg |
| Fat-free (skim) milk | 8.63 lb | 3.91 kg |
| Buttermilk | 8.62 lb | 3.91 kg |
| Flavored milk (USDA factor) | 8.00 lb | 3.63 kg |
| Water, for comparison | 8.34 lb | 3.78 kg |
Every Carton Size
Same USDA factors, scaled to the containers you actually buy. Whole milk shown; skim and 2% are within a few hundredths of a pound.
| Container (whole milk) | Fluid ounces | Weight |
|---|---|---|
| Gallon | 128 fl oz | 8.6 lb (3.9 kg) |
| Half gallon | 64 fl oz | 4.3 lb (1.95 kg) |
| Quart | 32 fl oz | 2.15 lb (975 g) |
| Pint | 16 fl oz | 1.08 lb (488 g) |
| Cup | 8 fl oz | about 8.6 oz (244 g) |
| Imperial (UK) gallon | 160 imperial fl oz | about 10.3 lb (4.7 kg) |
Why Skim Milk Weighs More Than Whole
This one surprises everybody at my table. Milk is mostly water, plus protein, lactose, minerals and fat. Fat is lighter than water, so the more cream you skim off, the denser what’s left becomes.
The difference is tiny, though: 8.60 lb for whole milk against 8.63 lb for skim is about half an ounce per gallon. You’d never feel it carrying the jug, but it’s a fun one to win a kitchen argument with.
How the Math Works
If you’d like to check it yourself, it takes one line. A US gallon is 231 cubic inches, which is 3.785 liters, and whole milk weighs about 1.03 kg per liter.
- 3.785 liters × 1.03 kg per liter = 3.90 kg
- 3.90 kg × 2.2046 lb per kg = 8.6 lb
- Water is about 1 kg per liter (see the USGS on water density), so the same jug of water is about 8.34 lb
Does the Jug Change the Weight?
A little. The figures above are for the milk alone. A plastic gallon jug adds a couple of ounces, while a returnable glass gallon bottle adds a lot more, so a full glass jug can feel noticeably heavier than the plastic one.
If you need an exact number for a recipe or a shipping label, I weigh the full jug, pour the milk out, weigh the empty jug and subtract. Two minutes and a kitchen scale.
Milk Weights for Baking
I bake by weight whenever I can, and milk is one of the easiest swaps from cups to grams. USDA FoodData Central lists 1 cup of whole milk at 244 g.
- 1 cup whole milk: 244 g (8.6 oz)
- 1/2 cup: 122 g
- 1/4 cup: 61 g
- 1 tablespoon: about 15 g
Storing That Gallon
Keep milk in the fridge at 40°F or below and put it back as soon as you pour. The USDA advises not leaving perishable foods like milk out for more than 2 hours, or 1 hour above 90°F. Once opened, I use a gallon within about 7 days and always give it a sniff before pouring.
Keep Reading
Left the jug on the counter? Here’s how long milk can safely sit out. Converting smaller amounts? See how many ounces are in a quart and how many ounces are in a shot glass.
Frequently Asked Questions
How much does a gallon of milk weigh?
A US gallon of whole milk weighs about 8.6 pounds (3.9 kg). That's the USDA's conversion factor of 8.60 lb per gallon. Reduced-fat milk weighs 8.62 lb and skim 8.63 lb, and the jug adds a few ounces.
How much does a gallon of milk weigh in kg?
About 3.9 kg. A US gallon is 3.785 liters and whole milk weighs about 1.03 kg per liter, so 3.785 x 1.03 comes to roughly 3.9 kg.
Is a gallon of milk heavier than a gallon of water?
Yes, by about 3%. A gallon of water weighs about 8.34 lb and a gallon of whole milk about 8.6 lb, because the protein, lactose and minerals in milk make it denser than water.
How much does a half gallon of milk weigh?
A half gallon of whole milk weighs about 4.3 lb (1.95 kg). Skim and 2% come in at about 4.31 lb, based on the USDA's per-container factors.
Does skim milk weigh more than whole milk?
Very slightly. The USDA puts skim at 8.63 lb per gallon and whole at 8.60 lb. Milk fat is lighter than water, so removing it leaves a denser liquid, but the gap is only about half an ounce per gallon.
How much does a UK gallon of milk weigh?
An imperial gallon is 4.546 liters, bigger than the US gallon, so it holds about 4.7 kg (10.3 lb) of whole milk. Most UK milk is sold in pints and liters, so you'll rarely carry a full imperial gallon.
