Grams are one of the foundational units in the metric system. They are used to measure weight and mass, and give rise to the other metric measurement prefixes, such as kilogram (kg) and milligram (mg). They’re also a key part of everyday life—from cooking ingredients to medication dosages to postage rates—and help us understand our world.
In the United States, grams are the most commonly used unit for non-liquid cooking and grocery shopping ingredients, as well as produce. Often, food nutrition labels must state relative composition per 100 grams, even within the United States.
Many people may have heard of the term “grams” in terms of their weight, but they may not know what a gram is. It may seem like an intimidating concept, or maybe it brings to mind the horror of high school science class. But, the truth is that grams are all around you. You see them on food labels next to proteins, carbohydrates, fats, and more. And, if you’re tracking your macros, they’re essential to hitting your targets each day.
Scientists from NPL played a central role in the historic change to the definition of the kilogram that took place on 20 May 2019. Watch this 90-minute documentary from MontanaPBS to learn about NIST’s contribution and the history of the kilogram. The film features scientists from across the globe who worked on the metrology that made this profound change possible. It’s called “In the Balance: The Story of the Kilogram.” You can find more information about NIST’s work on the kilogram at the BIPM website. grams