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DD.2 Convert and compare customary units of weight

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Understanding customary units of weight

Customary units of weight are measurement units commonly used in the United States to measure how heavy objects are. The main units are ounces, pounds, and tons.

Examples:
  • A slice of bread weighs about 1 ounce
  • A textbook weighs about 2 pounds
  • A small car weighs about 1 ton
Note

Weight measures how heavy something is, while mass measures the amount of matter in an object. On Earth, we often use these terms interchangeably.

Weight unit relationships

Customary weight units relate to each other through specific conversion factors that never change.

Key Relationships:
  • 16 ounces (oz) = 1 pound (lb)
  • 2,000 pounds (lb) = 1 ton (T)
  • 32,000 ounces (oz) = 1 ton (T)
Note

Remembering that 16 ounces equal 1 pound will help you solve most weight conversion problems.

Converting between weight units

To convert between weight units, multiply or divide using the conversion relationships.

Conversion Examples:
  • Converting ounces to pounds: 48 oz ÷ 16 = 3 lb
  • Converting pounds to ounces: 4 lb × 16 = 64 oz
  • Converting pounds to tons: 6,000 lb ÷ 2,000 = 3 T
  • Converting tons to pounds: 2 T × 2,000 = 4,000 lb
Note

When converting to a larger unit, divide. When converting to a smaller unit, multiply.

Comparing different weight units

To compare weights measured in different units, convert them to the same unit first, then compare.

Comparison Examples:
  • Which is heavier: 28 ounces or 2 pounds?
    28 oz = 1.75 lb, so 2 pounds is heavier
  • Which is lighter: 3,500 lb or 2 T?
    2 T = 4,000 lb, so 3,500 lb is lighter
  • Put in order from lightest to heaviest: 40 oz, 3 lb, 48 oz
    40 oz = 2.5 lb, 48 oz = 3 lb, so order is: 40 oz, 3 lb, 48 oz
Note

Always convert all measurements to the same unit before comparing them.

Solving real world weight problems

Weight conversions help solve everyday problems involving cooking, shipping, and other practical situations.

Real-World Applications:
  • Cooking: A recipe needs 2 pounds of apples. You have 28 ounces. Do you have enough?
    28 oz = 1.75 lb, so you need 0.25 lb more
  • Shipping: A package weighs 5 pounds 8 ounces. What is its weight in ounces?
    5 lb × 16 = 80 oz, plus 8 oz = 88 oz total
  • Groceries: Which is the better buy: 48 oz of cereal for $4.50 or 3 lb for $5.00?
    3 lb = 48 oz, so 48 oz for $4.50 is the better buy
Note

Many real-life situations require converting between different weight units to make decisions.