Metric System: Milligrams vs. Milliliters

Your kitchen is a good place to become familiar with the Metric System, but some of the measurements might be a bit confusing, especially when it comes to milligrams vs milliliters. In this article we'll take a look at the difference between a milligram (mg) and a milliliter (ml), along with when and why milligrams sometimes become milliliters, and vice versa. The 'official' definition of a milliliter is one-thousandth of a liter, but that might not help shed light on the milligrams vs. milliliters thing, so here's our unofficial explanation:

What is a milliliter?

The milliliter is probably more confusing than the milligram because for many of us, liters usually apply to liquids - a liter of water, two-liter bottle of soda, liter of gasoline, etc., but milliliters also apply to dry or solid products such as flour, butter, and chocolate chips. That's because a milliliter is a measurement of volume regardless of whether it's a liquid or solid. A milligram on the other hand, measures weight.

Difference between milligrams and milliliters

The difference between milligrams and milliliters is simply that a milligram is a unit of weight or mass, and a milliliter is a unit of volume. It's actually the same as our current Imperial System - the Metric System just uses different terminology. When you buy flour in a five-pound bag, it's a unit of weight/mass. When your recipe calls for two tablespoons of that flour, those two tablespoons are now measured in volume, not weight. If you decide to weigh the two tablespoons of flour, they're now back to pounds/ounces because you're using a different measurement: one of weight, not volume.

Kilograms to milligrams and milliliters

The Metric System is the same. When you buy a 2.2 kilogram bag of flour and measure the same two tablespoons, the measurement now becomes 30 milliliters (each tablespoon is 15 ml) unless you weigh it. Then it's back to milligrams.