Ratios to Convert Meausrements

Contributor: Ashley Nail. Lesson ID: 13892

Do you know how to convert between inches and feet, or pounds and ounces? Learn how to use equivalent ratios to figure out tricky conversions!


Middle School, Pre-Algebra, Ratios, Rates, Percentages, and Proportions

learning style
Kinesthetic, Visual
personality style
Lion, Otter, Beaver, Golden Retriever
Grade Level
Middle School (6-8)
Lesson Type
Quick Query

Lesson Plan - Get It!

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Eilah is helping with her mom’s small business. Eilah’s mom makes orange juice to sell at the local farmers’ market.

Eilah and her mom make large batches of orange juice and fill gallon jugs to sell. So far, Eliah has made 32 cups of orange juice, which fills 2 gallon jugs.

2 gallon jugs of juice

  • Is 84 cups enough orange juice to fill 5 gallon jugs?

To answer Eilah’s question, you need to figure out how many cups are in 5 gallons.

Look more closely at the information you know.

There are 32 cups of orange juice in 2 gallon jugs.

This can also be written as a ratio.

32 : 2

To answer Eilah’s question, you are looking for a ratio equivalent to 32 : 2.

First, find out how many cups are in just 1 gallon. This simplified ratio will help you  convert measurements later.

You can divide each part of the ratio by 2 to find an equivalent ratio.

equivalent ratio

This will give us the answer to how many cups are in 1 gallon.

cups in a gallon

16 cups of orange juice will fit in a 1-gallon jug.

16 : 1 is equivalent to 32 : 2

Now, you can use this equivalent ratio to find how many cups are in 5 gallons.

cups in 5 gallons

To get from 1 to 5, you need to multiply by 5. Then, multiply the other side of the ratio by 5 also.

multiply by 5

Now you know there are 80 cups in 5 gallons.

80 : 5 is equivalent to 16 : 1 and 32 : 2

  • How can you convert 48 cups into gallons?

48 cups

We need to figure out what number, when multiplied by 16, will give you 48. Then, multiply both sides of the ratio by that number to find an equivalent ratio.

what times 16 equals 48

3 gallons is equal to 48 cups

These are all equivalent ratios.

  • 32 : 2
  • 16 : 1
  • 80 : 5
  • 48 : 3

To further prove that these ratios are equivalent, you can look at them as fractions.

ratios as fractions

Now you are ready to practice on your own!

Click NEXT to visit the Got It? section to practice using ratios to convert measurements.

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