What are you really paying?

Have you ever purchased a product that stated on the label: 1 U.S. Gallon, but when opened it wasn’t quite full? Sure you have – it happens all the time. But, the real question is, “Did you get what you paid for?” Or were you shorted? This article discusses the matter and gives advice on how to assure that you are getting what you pay for.

Bill Hood, ASDPT Fellow

Which weighs more a gallon of adhesive or a gallon of gasoline?

If you think they should both weigh the same, you are right, but the US government says that you are wrong, and thus you can blame it on the government, which refuses to use the metric system.

Manufacturers label many products by the capacity of the container in which they package the product. This circumvents them from liability for slight variances such as would be noticeable if the product were weighed against the weight on the label. They fill the container to the fill line and consider that it is 1-gallon. And, they do not have to have different labels printed for different products that may be placed into the container.

However, both the gallon and the liter have a specific volume that the product must equal as is legally defined (by the International Bureau of Weights and Measures[1]). There are actually three different gallons in existence as defined below.

The imperial gallon

The imperial (UK) gallon, now defined as exactly 4.54609 liters, is used in some Commonwealth countries and was originally based on the volume of 10 pounds (approximately 4.54 kg) of water at 62 °F (17 °C). The imperial fluid ounce is defined as 1160 of an imperial gallon; there are four quarts in a gallon, two pints in a quart, and 20 fluid ounces in an imperial pint.

The US liquid gallon

The US gallon, which is equal to approximately 3.785 liters, is legally defined as 231 cubic inches. A US liquid gallon of water weighs about 8.34 pounds or 3.78 kilograms at 62 °F (17 °C), making it about 16.6% lighter than the imperial gallon. There are four quarts in a gallon, two pints in a quart and 16 fluid ounces in a US pint, which makes a US gallon equal to 128 fl. oz.

And, yes, you may have already guessed that 128 fl. oz. of white ink is less volume than 128 fl. oz. of black ink. This is because white ink is made of titanium white pigment, which is very heavy, compared to black ink which is made of carbon black pigment.

In order to overcome the effects of expansion and contraction with temperature when using a gallon to specify a quantity of material for purposes of trade, it is common to define the temperature at which the material will occupy the specified volume. For example, the volume of petroleum products and alcoholic beverages are both referenced to 60 °F (16 °C) in government regulations.

This can lead to different weights. For example a gallon of;

Adhesive weighs 9.14 pounds
Milk weighs 8.6 pounds
Water weighs 8.4 pounds
Olive oil is around 7.6 pounds
Crude oil weighs 7.2 pounds
Recycled motor oil weighs 7 pounds
Gasoline weighs 6 pounds

The US dry gallon

This gallon is one-eighth of a US “Winchester” bushel of 2,150.42 cubic inches; it is, therefore, equal to exactly 268.8025 cubic inches or 4.40488377086 L. The US dry gallon is not used in commerce and is not listed in the relevant statute, which jumps from the dry quart to the peck.

For ease of explanation let’s use the U.S. Liquid Gallon for this article. The U.S. gallon (abbreviation “U.S. gal”) as a measure of liquid capacity of 3.785 Liters.

The term “liter” a metric unit of capacity, legally defined as equal to 1,000 cubic centimeters or the volume of a cube with equal 10 cm sides.

In other words, the “U.S. Gallon” is supposed to contain 3.785 liters of substance, regardless of the size or shape of the container. As an example, if the bucket held 3.785 liters, it should come to the fill line. And, it would completely fill a cube that measured 37.85 cm on all sides, with no air gaps present.

A gallon of ink

Let’s get a bit more specific and assume that the product is plastisol ink. The problem begins because not all colors when placed in the 1-gallon container to the fill line will weigh the same. A gallon of white ink, which contains titanium will be heavier than say a gallon of black, which contains carbon.

However, if you fill the bucket with a thick ink that does not settle easily, there could be large air gaps in the bucket. As the ink settles during shipment or when heated in a hot warehouse, it will settle. And, yes five buckets of thick ink will settle with slight, but visual, differences.

One would think that the ink company would simply fill a container that measured 37.85 cm on all sides with a specific color of ink from their product line and weigh the contents minus the container to arrive at a weight of what is supposed to be in the bucket they will fill. During filling the bucket would sit on a scale that would show the true weight. If the fill line were reached, but the scale would point out that there must be air pockets within the bucket that need to be eliminated.

And, of course, that is how you find out if you have been shorted or not – by weight. The smart printer would fill a pint container of a specific product, let’s say a white ink from the brand name that is in use in the shop, avoiding all air gaps. Allow this to settle, then heat to 60 °F (16 °C) and weigh the product, deducting the weight of the container. Since there are 8 pints in a gallon, any subsequent deliveries of a gallon of this particular product should weigh 8 times the base weight, less the container. A 5-gallon container should weigh 40 times the base weight, less the container.


Most printers use ink software today that allow them to accurately estimate how much ink they will need for a specific number of items. These are available from most major ink manufacturers and will work (with some slight adaption) with any ink, regardless of the manufacturer. None of these are perfect due to the variances in the printing technique. For instance, a slight increase in pressure also increases the amount of ink needed to provide opacity.

Let’s assume that you are running a single automatic textile press printing white ink on black t-shirts and the press is averaging 500 pieces an hour. Your average calculations when using this particular white ink printed through a 156-64 mesh with a 40% coverage shows a cost of $0.06 per each printed piece.

As the press could easily print 2,500 pieces in a 5-hour period and up to 12,500 pieces a week or 650,000 pieces a year. If you ink cost to print these 650,000 pieces was just .06 each your ink cost would be $39,000 a year. An average 10% shortage would cost you $3,900 a year.

Of course, your numbers will vary from those used in this example and may be higher or lower, but still, that shortage adds up. It is in your best interest to assure that you are not shorted.

Gross Weight vs Net Weight

Knowing the difference between gross weight and net weight is necessary. You can be easily duped by comparing the stated weight of a product against a competitive brand.

You are often impressed by the packaging of a product without realizing you are being charged for it. As an example:

A chemical that you use on a regular basis is in a plastic bottle with a label that states it contains 35 net ounces and costs $23. A sales representative stops by one day and tells you that he has a better product for less money, but it comes in a container that is much larger and thus you will also save on packaging costs. He shows you a container of the product that he happens to have in his car. The label states that 70 oz., the container is much larger and also a more substantial thickness to the walls of the plastic bottle. You see this as a good feature. And, his product costs only $20. Everything looks good so you place an order to make the switch.

In actuality, his bottle did not contain twice as much of the product as the one you were using. His bottle did not use the word net, which means it was a gross weight, which is the total of the actual weight of the product plus the packaging weight.

Later you find that by pouring his product into the empty bottle of the product he hoped to replace that it was only 75% full. The first product cost $0.657 per oz. The second product cost $0.769 per ounce, after deducting the weight of the container. This all comes down to the fact that you ended up paying 15% more for the second product. Not such a great deal after all.

Thus, it is important to look for net weight, paying no attention to the gross weight, as it can be misleading. Let us take a closer look at gross weight and net weight.

The concept of gross and the net is an important one and one that is being used since ancient times.

What is the difference between Gross Weight and Net Weight?

• Gross weight and net weight are two important concepts that are used by manufacturers, to inform the amount of the contents.

• Gross weight is the total of the actual weight of the product plus the packaging weight.

• Net weight is the actual weight of the product without any packing material.

• If the packaging is heavy, you may actually pay more for the packaging rather than the product, which is a wrong practice.

Legal cases

Whole Foods Market is paying $800,000 in penalties after an investigation found the supermarket chain overcharged customers throughout California. However, this penalty was a drop in the bucket (pun intended) compared to how much margin the company earned because of the deceptive pricing.

During a yearlong investigation, state and local inspectors found the Austin, Texas, grocer charged more than advertised for a wide range of food products, according to a statement from the Santa Monica city attorney’s office.

Among the problems at Whole Foods Market stores in California:

  • Problems included failing to deduct the weight of containers when charging by weight.
  • The weight of the product was less than the stated weight on the label.
  • Selling items by the piece instead of by the pound, as required by California law.

Santa Monica Deputy City Atty. Adam Radinsky said that shoppers have a right to transparent pricing.

“By adding the weight of containers and packaging, especially on higher-priced, per-pound items like seafood and meats and even prepared food, the extra charges can add up fast, and yet be hidden from consumers,” he said in the statement.

In response, Whole Foods attempted to explain that they strive to ensure accuracy and transparency and that the difference was only 2%, but with $14.2 billion in reported sales for 2014, that extra 2% amounts to $284 million dollars in margin for Whole Foods.


1. International Bureau of Weights and Measures

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