US Standard Mass (Weight)

These are the most common measurements:

"Ounce" is used for weight and for volume.

If you mean an ounce of weight, say "ounce weight",
but if you mean an ounce of fluid say "fluid ounce" ("fl oz")

Here we will talk about ounce weight

The smallest unit of weight is ounces (oz). One ounce weighs about the same as a slice of bread. It is very light.

The abbreviation for ounce is "oz", because it came from the 15th century Italian word "onza".

When you add up the ounces you get a new label for weight.

If you have 16 ounces, it can also be called a pound (lb).

1 pound = 16 ounces

The abbreviation is "lb", because it came from the Latin word "libra".

Typically, this is the unit that you use to measure your own weight.

Pounds are used to measure lots of things from people to food to animals.

However, if something weighs many pounds we use yet another label

Tons

Anything that weighs 2,000 pounds can also be weighed in tons. One ton is the same as 2,000 pounds.

1 ton = 2,000 pounds

That is really heavy! Trucks, ships and heavy equipment are measured using tons instead of pounds.

An elephant weighs about 7 tons

And this car weighs about 2 tons.

But in some countries a "ton" can mean 2,240 pounds, so to be clearer people use "short" and "long" in front of "ton", like this:

Final thoughts about measuring weight:

1 pound = 16 ounces

1 Ton (also called "Short Ton") = 2,000 pounds = 32,000 ounces

1 Long Ton = 2,240 pounds

We have been talking about weight here only because that is what people commonly say.

But we should really be calling these measures "Mass". See Weight or Mass? for a full explanation.

"Ounce" normally means "Avoirdupois Ounce", but there is also "Troy Ounce"

The International avoirdupois ounce is 28.349523125 grams (normal meaning of "ounce")
The International troy ounce is 31.1034768 grams

An ounce of mass is:

A pound is:

A short ton is: