Metric Mass Units (mg, g, kg, t)
Learn all metric mass units from milligrams to tonnes and how to convert between them.
Definition
| Unit | Symbol | Equal To |
|---|---|---|
| Milligram | mg | of a gram |
| Gram | g | Base unit |
| Kilogram | kg | grams |
| Tonne | t | kilograms |
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Worked Examples
A tablet contains g of medicine. How many milligrams is this?
Identify the conversion
g mg → Multiply by 1000
Apply the conversion
→
Add the unit
mg → Answer in milligrams
Answer: g mg
Common Mistakes
Multiplying when you should divide (or vice versa)
Why it's wrong: Going from a smaller unit to a larger unit means you have fewer of them, so you divide.
Correct: Smaller to larger unit = divide. Larger to smaller unit = multiply. Example: g to kg = divide by 1000.
Forgetting that 1 tonne = 1,000,000 grams
Why it's wrong: Students often only remember kg to g conversion and forget the tonne relationship.
Correct: t kg, and g
Confusing mass and weight in contexts
Why it's wrong: In everyday language, we use these interchangeably, but mass is measured in grams/kg.
Correct: On Earth, mass and weight are proportional. Use metric units (g, kg) for mass measurements.
Interactive Visual
Weight Converter
1 g = 1000 mgInteractive Sandbox
Expression Calculator
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Practice Problems
15 problemsHow many milligrams are in 1 gram?
Why It Matters
- Medicine: A vitamin pill might contain mg of vitamin C
- Cooking: A recipe might call for g of flour
- Body weight: An adult might weigh kg
- Shipping: A truck might carry tonnes of cargo
Real World Applications
Medicine and Supplements
Medicine doses are often measured in milligrams because the amounts are very small.
Example:
A pain reliever tablet might contain mg of the active ingredient. That is only g!
A prescription says to take mg of medicine three times daily.
How many grams of medicine do you take in one day?
Step 1: Write the mathematical expression
First find total mg: , then convert to grams
Cooking and Recipes
Recipes use grams for precise measurements, especially in baking.
Example:
A cake recipe needs g of flour, g of sugar, and g of butter.
A recipe calls for kg of potatoes. You have g.
How many more grams of potatoes do you need?
Step 1: Write the mathematical expression
Convert kg to grams, then subtract
Shipping and Transport
Heavy loads are measured in tonnes because kilograms would give very large numbers.
Example:
A shipping container might weigh tonnes. That is kg or g!
A truck can carry up to tonnes. It is loaded with items weighing kg.
How many more kilograms can the truck carry?
Step 1: Write the mathematical expression
Convert tonnes to kg, then subtract
Key Takeaways
- 1Metric mass units: milligram (mg), gram (g), kilogram (kg), tonne (t)
- 2Each unit is times the previous: g mg, kg g, t kg
- 3To convert to a smaller unit, multiply by
- 4To convert to a larger unit, divide by
- 5Remember: milli = thousandth, kilo = thousand
Frequently Asked Questions
Glossary
- Milligram (mg)
- One thousandth of a gram. Used for very small masses like medicine doses.
- Gram (g)
- The base unit of mass in the metric system. About the mass of a paperclip.
- Kilogram (kg)
- One thousand grams. The standard unit for body weight and medium-sized objects.
- Tonne (t)
- One thousand kilograms, also called a metric ton. Used for very heavy objects like vehicles.
- Prefix
- A word part added to the beginning of a unit name to change its value (milli-, kilo-).