You can make skim milk from whole milk by letting the cream rise to the top and then scooping it off. The catch: this only works with non-homogenized (sometimes called “cream-top”) whole milk. The homogenized whole milk sold in most grocery stores has been processed specifically to prevent the cream from separating, so no amount of waiting will produce a cream layer you can skim.
Why Store-Bought Milk Won’t Separate
During commercial processing, milk is forced at high pressure through a tiny valve in a step called homogenization. This breaks the natural fat globules into much smaller, uniformly sized particles that stay evenly distributed throughout the liquid instead of floating to the top. The process also changes the electrical charge on the surface of each fat particle, making the whole mixture more stable. That’s why a jug of whole milk from the supermarket looks the same from top to bottom, even after sitting in your fridge for a week.
To skim milk at home, you need non-homogenized whole milk. Look for it at farmers’ markets, dairy farms that sell direct, or in the specialty section of well-stocked grocery stores. The label will typically say “cream-top” or “non-homogenized.” Raw milk also works, though availability depends on your state’s regulations.
The Gravity Method: Let Cream Rise Naturally
Fat is lighter than the watery portion of milk, so in non-homogenized milk, cream gradually floats upward on its own. The speed depends on temperature. Research on gravity separation found that milk held at 12°C (about 54°F) for 7 hours produced the same degree of fat separation as milk held at 4°C (standard refrigerator temperature, around 39°F) for 22 hours. In practical terms, if you put a jar of cream-top milk in your fridge, plan on leaving it undisturbed for at least 24 hours to get a clear cream layer.
Use a wide-mouth glass jar or a deep bowl rather than a narrow container. A wider opening gives you more surface area, which makes the cream layer easier to see and remove. A clear container is helpful so you can watch the cream line form along the side. Place the container on a stable shelf where it won’t get bumped or jostled, since any movement remixes the fat back into the milk.
Removing the Cream
Once the cream has risen into a visible layer on top, you need to lift it off without stirring it back in. A few tools work well:
- A shallow ladle or large spoon. The simplest option. Gently slide it just under the surface and scoop the cream into a separate bowl. This is quick and leaves you with only one utensil to clean.
- A small measuring cup. A quarter-cup measure with a thin edge works particularly well. It lets you skim in small, controlled passes along the surface.
- A turkey baster. Squeeze the bulb, touch the tip to the cream layer, and release slowly. This gives you more precision but takes longer for a full jar.
The trickiest part is avoiding the boundary between cream and milk underneath. Move slowly and keep your tool nearly horizontal. You won’t get every last bit of fat, and that’s fine. Even commercial skim milk contains a small amount of fat (up to about 0.5%). If you’re aiming for something close to store-bought skim, remove as much of the visible cream layer as you can in two or three careful passes rather than trying to scrape it perfectly clean in one go.
What About a Cream Separator?
If you regularly process milk at home, a manual or electric cream separator does the job faster and more thoroughly. These machines spin milk at high speed, using centrifugal force to push the heavier skim milk outward while the lighter cream collects in the center and flows into a separate spout. Commercial dairy separators spin at around 5,400 RPM, though home models vary. The result is a cleaner split between cream and skim than you’ll get by hand.
The downside is cost and cleanup. A decent home separator runs anywhere from $80 to several hundred dollars, and the machine has multiple discs and small parts that need to be disassembled and washed after every use. For someone skimming a gallon or two a week, most home dairy enthusiasts find hand skimming with a ladle easier and perfectly adequate.
What You Lose When You Skim
Removing the cream removes more than just fat. Vitamins A, D, E, and K are all fat-soluble, meaning they’re carried in the butterfat portion of milk. When researchers measured vitamin A levels before and after skimming, they found that reducing butterfat from 3.5% to 0.5% caused an 83% drop in vitamin A content. The other fat-soluble vitamins follow a similar pattern, since they partition into whatever fat is removed.
This is why commercial skim milk in the U.S. is typically fortified with vitamins A and D after processing. Your homemade skim milk won’t have that fortification, so keep that in mind if skim milk makes up a significant part of your diet. The protein, calcium, and B vitamins in milk are water-soluble and stay behind in the skim portion.
What to Do With the Cream
One benefit of skimming your own milk is that you end up with fresh cream. Depending on how carefully you skim, it will range from something like half-and-half to a thicker heavy cream. You can whip it, churn it into butter, pour it into coffee, or use it in cooking. Stored in a sealed jar in the fridge, fresh cream keeps for about a week. If you accumulate more cream than you can use, it freezes well for several months.