Last updated: October 22, 2026 · Written by the Math Made Easy math teachers
Looking for 6th grade unit conversion? Then this Grade 6 lesson on Converting Units with Ratio Reasoning explains each idea step by step, with worked examples.
Quick answer: To convert units, use the ratio between them, such as 12 inches per 1 foot or 1,000 meters per 1 kilometer. Multiply when changing to a smaller unit and divide when changing to a larger one. For multi-step conversions, chain the equivalences one unit at a time.
Standards: 6.RP.A.3d · Level: Grade 6
What is a unit conversion?
A unit conversion writes the same amount in a different unit. A conversion factor is a ratio of equal measures, such as 3 feet per 1 yard, so multiplying by it never changes the size of the amount.
Which equivalents should you know?
| Customary | Metric |
|---|---|
| 12 in = 1 ft; 3 ft = 1 yd | 1 km = 1,000 m |
| 5,280 ft = 1 mi | 1 m = 100 cm; 1 cm = 10 mm |
| 16 oz = 1 lb | 1 kg = 1,000 g |
| 2 cups = 1 pt; 2 pt = 1 qt; 4 qt = 1 gal | 1 L = 1,000 mL |
How do you convert with a ratio table?
Going from a larger unit to a smaller unit gives more of the smaller unit, so multiply. Going from a smaller unit to a larger unit, divide.
- Write the equivalence as the first column: 12 inches = 1 foot.
- Find what turns the first row into your amount.
- Apply the same number to the other row.
- Attach the unit and ask whether the size makes sense.
Convert 54 inches to feet.
Inches are smaller than feet, so divide: 54 ÷ 12 = 4.5.
Answer: 4.5 feet.
How do you do a multi-step conversion?
Chain the equivalences so that each step uses one familiar fact. To change 6 gallons to cups, go from gallons to quarts, then to pints, then to cups.
Write each step so that a reader can follow it. The calculation is 6 × 4 = 24, then 24 × 2 = 48, then 48 × 2 = 96, so 6 gallons is 96 cups.
Multiplying when you should divide. Since a foot is bigger than an inch, a length in feet must be a smaller number than the same length in inches.
Before you finish, do a size check: if you convert to a smaller unit, your number should grow. If it shrinks, you probably divided by mistake.
- A conversion factor is a ratio of equal measures, like 3 feet per 1 yard.
- Larger unit to smaller unit: multiply. Smaller unit to larger unit: divide.
- Know 12 in = 1 ft, 3 ft = 1 yd, 5,280 ft = 1 mi, 16 oz = 1 lb, 4 qt = 1 gal.
- Metric conversions use powers of ten, such as 1 km = 1,000 m.
- Ratio tables and double number lines organize each conversion.
Converting Units with Ratio Reasoning: frequently asked questions
What is a conversion factor?
A conversion factor is a ratio that equals 1 because both parts are the same amount, such as 3 feet per 1 yard. Multiplying by it changes the unit but not the size.
When do you multiply and when do you divide?
Multiply when going to a smaller unit, because you need more of them. Divide when going to a larger unit, because you need fewer.
How many cups are in a gallon?
A gallon has 4 quarts, each quart has 2 pints, and each pint has 2 cups. So 4 × 2 × 2 = 16 cups.
How do you convert metric units?
Use the powers of ten: 1 km = 1,000 m, 1 m = 100 cm, 1 kg = 1,000 g and 1 L = 1,000 mL. Multiply or divide by that number.
How do you compare two measurements in different units?
Convert both to the same unit and compare the numbers. For example, 2.4 m is 240 cm, which is longer than 235 cm.
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