# Standard Units

You are probably familiar with a lot of these measurements. Weight is about how heavy and object is. You can answer questions with "How much" and "How heavy" with these values.

1 pound = 16 solid ounces
1 short ton = 2,000 pounds = 32,000 ounces
1 ton = 2240 pounds = 35,840 ounces
1 troy ounce (used in gold) = 1.1 ounces

# Metric Units

The basis of length units for the metric system is the kilogram. A kilogram weighs about the same as two and one quarter pounds. You already read that the metric system is based on units of ten so here's a starter list, but they go on forever. There is a small difference between standard and metric units in this section. Metric units represent mass anywhere. They weigh different things on other planets.

Let's clear this up. A pound is a pound on Earth. If you go to the Moon there is a different gravity and a pound no longer weighs a pound. However a kilogram is a kilogram anywhere in the Universe. It does have a different weight on the Moon though (about 0.6 of what it weighs on Earth). Physics classes will explain all of this further. We just want to let you know there is a difference between mass and weight.

1 kilogram = 1,000 grams
1 tonne = 1,000 kilograms = 1,000,000 grams

# Conversion

You're going to have to go back and forth with units. Converting ounces into grams and pounds into kilograms is a regular thing in math and science classes. Here are a few conversions. Technically you only need one conversion, but sometimes it's easier to use one closer to the values you want.

1 ounce = 28.34 grams
1 pound = 0.45 kilograms = 450 grams
1 short ton = 0.9 tonnes = 900 kilograms = 900,000 grams

1 gram = 0.035 ounces
1 kilogram = 2.2 pounds = 35.2 ounces
1 tonne = 1.1 short tons = 35,200 ounces

# Example

If I were going to the grocery store to buy some roast beef and I bought two pounds. How many grams would that be?
2 pounds = 32 ounces = 32 * 28.34 grams = 906.88 grams ≈ 0.9 kilograms

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