Measurement and Unit Conversion
Grade 4 · Math · Study Guide
Learn to measure length, weight, and capacity and convert between units.
Measurement is how we describe size, weight, distance, and capacity using numbers and units. In 4th grade, you work with both the customary system (used mainly in the U.S.) and start learning the metric system.
In the customary system, length is measured in inches, feet, yards, and miles. The key conversions: 12 inches = 1 foot, 3 feet = 1 yard, and 1,760 yards = 1 mile. Weight uses ounces, pounds, and tons: 16 ounces = 1 pound, 2,000 pounds = 1 ton. Capacity (liquid volume) uses cups, pints, quarts, and gallons: 2 cups = 1 pint, 2 pints = 1 quart, 4 quarts = 1 gallon.
Converting within the same system means multiplying when going to smaller units and dividing when going to larger units. For example, to convert 3 feet to inches: 3 × 12 = 36 inches. To convert 48 inches to feet: 48 ÷ 12 = 4 feet.
The metric system uses meters, grams, and liters as base units. Prefixes like kilo- (1,000 times) and centi- (1/100) make conversions easy. 1 kilometer = 1,000 meters, and 100 centimeters = 1 meter.
| Type | Conversion |
|---|---|
| Length | 12 inches = 1 foot |
| Length | 3 feet = 1 yard |
| Weight | 16 ounces = 1 pound |
| Capacity | 2 cups = 1 pint |
| Capacity | 2 pints = 1 quart |
| Capacity | 4 quarts = 1 gallon |
Key terms
- Customary system
- The measurement system used in the U.S., using inches, pounds, and gallons.
- Metric system
- A measurement system using meters, grams, and liters with decimal-based conversions.
- Convert
- Change a measurement from one unit to another.
- Capacity
- The amount a container can hold, measured in cups, pints, quarts, or gallons.
Flashcards
- Inches in 1 foot
- 12 inches
- Feet in 1 yard
- 3 feet
- Ounces in 1 pound
- 16 ounces
- Quarts in 1 gallon
- 4 quarts
- Cups in 1 pint
- 2 cups
- Converting feet to inches
- Multiply by 12. Example: 5 feet = 5 × 12 = 60 inches.
Practice questions
How many inches are in 4 feet?
- 16
- 36
- 48
- 52
Show answer
Answer: 48
4 feet × 12 inches/foot = 48 inches.
There are 4 quarts in 1 gallon.
Show answer
Answer: True
The conversion fact is: 4 quarts = 1 gallon.
36 inches equals ___ feet.
Show answer
Answer: 3
36 inches ÷ 12 = 3 feet.
How many ounces are in 3 pounds?
- 32
- 40
- 48
- 64
Show answer
Answer: 48
3 pounds × 16 ounces/pound = 48 ounces.
2 quarts is the same as ___ pints.
Show answer
Answer: 4
2 pints = 1 quart, so 2 quarts = 4 pints.
Fun facts
- A gallon of water weighs about 8.3 pounds — that is why big water jugs are so heavy!
- The ancient Egyptians measured length using body parts: a 'cubit' was the distance from your elbow to the tip of your middle finger.
Get a personalized course on Measurement and Unit Conversion built around your child.