What Are the Dimensions of A Gallon of Milk?

Many adults out there might not be able to recall the last time they chugged a gallon of milk. Perhaps their digestive systems have outgrown the delicious calcium-rich beverage, or maybe they only use it as an ingredient for a White Russian. But do you remember what the measurements of a gallon of milk are?

Milk gallons are irregularly shaped plastic containers with handles. The measurements of a gallon of milk are 10.5 inches tall and have a 5.5 × 5-inch footprint. The diameter of the cap is usually 38 millimeters (1.5 inches).

So, perhaps you’re wondering why milk in the US is sold in unique containers? Or perhaps you’re unsure why milk caps come in different colors? I’ll address your concerns and more in the following sections.

Dimensions of a Gallon of Milk

There is hardly a beverage out there that comes in such weirdly shaped containers as milk does. But before I address why that is, let’s first take a look at the overall dimensions of a gallon of milk.

• Height—10.5 inches
• Width—5.5 inches
• Depth—5 inches
• Cap Size—38-430

These figures do not take into account the irregularities on the milk gallon, such as the handle and the circular indentation.

For those who are wondering, the 38-430 cap size means that it measures 38 inches wide and is suitable for 1- to 2-turn threaded bottlenecks. It’s deeper than the traditional 400 and 415 neck finishes, which ensures better closure when the lid is screwed on.

How Many Quarts to a Gallon?

Milk is also normally sold by the quart, but it will come in paperboard cartons instead of plastic jugs. A quart of milk in a carton will usually measure 6.1 inches tall and have a base measuring 4.9 × 4.8 inches.

1 gallon is equal to 4 quarts, so you would need 4 1-quart cartons to have the same amount of milk as you would with a 1-gallon jug. But will buying 4 quarts save space? Let’s find out.

• 1-quart carton= 6.1 × 4.9 × 4.8 inches
• 1-quart carton = 143.472 cubic inches
• 1 gallon in 1-quart cartons = 4 × 143.473 = 573.888 cubic inches

• 1-gallon jug = 10.5 × 5.5 × 5 inches
• 1-gallon jug = 288.75 cubic inches
• 1 quart of milk from a 1-gallon jug = 288.75 ÷ 4 = 72.1875

So, based on these simple calculations, it’s clear that 4 cartons of 1-quart milk (1 gallon in total) actually takes up more space than a 1-gallon jug of milk. Add in the fact that 1-gallon jugs of milk are cheaper than 1-quart milk cartons per fluid ounce, you would have no reason to purchase 1-quart cartons of milk!

Why Are Milk Gallons Designed Like That?

First, let’s discuss the design of a milk gallon.

Milk gallons or jugs use food contact materials deemed safe by the United States Food and Drug Administration (FDA). Since the 1960s, plastic containers have largely replaced glass bottles. The plastic used for milk jugs is primarily high-density polyethylene (HDPE), but unlike other petroleum-based plastics, it is completely free of BPA.

As for why 1-gallon milk jugs come in their irregular shapes, it has more to do with logistics than anything else. The blocky-shaped design of a milk bottle allows retailers to store more gallons in coolers, which may prompt them to increase their purchase order quantity or frequency. If you pay close attention to the handles, they are angled slightly inward toward the cap, which lets retailers shelf 1-gallon milk jugs more closely together.

What Is the Circular Indentation in Milk Gallons?

The next time you purchase a gallon of milk, turn it over and look for the circular indent on one of its walls. It will usually be placed on the wall opposite the handle.

Although plastic milk gallons are rigid, it has a slight flex with pressed from the outside or inside. The indent is what gives the bottle its structural integrity. Without it, the milk would force itself out of the lid or possibly break through the plastic shell when dropped.

There’s another reason why the dimple is there. Although a milk container will have an expiration date, the circular indent will pop out when there is built-up pressure inside the gallon. This is usually a sign that the milk is past its prime. Instead of exploding, the dimple will pop out like an outie belly button, informing you to stay the heck away from it at all costs.

Why Do Milk Gallons Have Different Lid Colors?

When strolling down the dairy aisle of your favorite grocery store, take a gander at the milk jug gallons. Standing beside the milk cooler, it might look like you’re looking at a spectrum containing the colors of the rainbow. So, why do milk jug lids come in different colors?

The answer is quite simple—to inform the shopper of what type of milk it is. Different milk brands may have different color-code standards to denote what sort of milk is in the container. For instance, Clover Organic will use blue lids for their 2% milk, while Dairy Maid uses yellow lids for the same type of milk.

Here’s a quick rundown of the different milk container lid colors and the type of milk to expect:

As you can see, the majority of brands will stick to a universal color-coding system to inform shoppers of what type of milk is inside the container. However, the safest thing you can do is to carefully read the label to determine whether you’re getting 1%, 2%, whole, or skim milk.

Nutrition Facts of Milk

Let’s take a look at the nutrition facts table per 1-glass (16-ounce) serving of the various types of milk.

Taken from My Food Data