Converting Units of Measurement

Grade 5 · Math · Study Guide

Learn how to convert between units within the customary and metric measurement systems.

Measurement is used in everyday life, from cooking recipes to building projects. Units of measurement are organized into systems, and knowing how to convert between units within each system is an essential skill.

The customary system is commonly used in the United States. Key conversions to know: length (12 inches = 1 foot, 3 feet = 1 yard, 5,280 feet = 1 mile), weight (16 ounces = 1 pound, 2,000 pounds = 1 ton), and capacity (2 cups = 1 pint, 2 pints = 1 quart, 4 quarts = 1 gallon).

The metric system is based on powers of 10 and is used internationally. The prefixes tell you the relationship to the base unit: kilo- (1,000), hecto- (100), deka- (10), base unit, deci- (0.1), centi- (0.01), milli- (0.001). For example, 1 kilometer = 1,000 meters and 1 centimeter = 0.01 meters.

To convert to a smaller unit, multiply. To convert to a larger unit, divide. For example, to convert 3 feet to inches (smaller unit), multiply: 3 x 12 = 36 inches. To convert 48 inches to feet (larger unit), divide: 48 ÷ 12 = 4 feet.

Key terms

Customary system
The measurement system commonly used in the US, using units like inches, pounds, and gallons
Metric system
A measurement system based on powers of 10, using units like meters, grams, and liters
Conversion factor
The number you multiply or divide by to change from one unit to another
Convert
To change a measurement from one unit to an equivalent measurement in a different unit
Kilo-
A metric prefix meaning 1,000; for example, 1 kilometer = 1,000 meters
Centi-
A metric prefix meaning 1/100 or 0.01; for example, 1 centimeter = 0.01 meters

Flashcards

Feet to inches
Multiply by 12; example: 5 feet = 5 x 12 = 60 inches
Inches to feet
Divide by 12; example: 36 inches = 36 ÷ 12 = 3 feet
Pounds to ounces
Multiply by 16; example: 3 pounds = 3 x 16 = 48 ounces
Gallons to quarts
Multiply by 4; example: 2 gallons = 2 x 4 = 8 quarts
Kilometers to meters
Multiply by 1,000; example: 4 km = 4,000 m
Centimeters to meters
Divide by 100; example: 250 cm = 250 ÷ 100 = 2.5 m
Rule: converting to a smaller unit
Multiply by the conversion factor because more smaller units fit in the same space

Questions

  1. How many inches are in 4 feet?

    1. 36
    2. 48
    3. 40
    4. 60
    Show answer

    Answer: 48

    There are 12 inches in 1 foot. To convert 4 feet to inches, multiply: 4 x 12 = 48 inches.

  2. 1 kilometer = ___ meters.

    Show answer

    Answer: 1000

    The prefix kilo- means 1,000. Therefore 1 kilometer = 1,000 meters.

  3. To convert from feet to inches, you should divide by 12.

    Show answer

    Answer: False

    Feet is a larger unit than inches. Converting to a smaller unit means multiplying. To convert feet to inches, multiply by 12.

  4. How many quarts are in 3 gallons?

    1. 8
    2. 12
    3. 16
    4. 6
    Show answer

    Answer: 12

    There are 4 quarts in 1 gallon. To convert 3 gallons to quarts, multiply: 3 x 4 = 12 quarts.

  5. 48 ounces = ___ pounds.

    Show answer

    Answer: 3

    There are 16 ounces in 1 pound. To convert 48 ounces to pounds, divide: 48 ÷ 16 = 3 pounds.

Get a personalized course on Converting Units of Measurement built around your child.