Customary Unit Conversion
Practise converting US customary units — inches, feet, yards, ounces, pounds, cups, pints, quarts and gallons.
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How customary conversion works
Unlike the metric system, US customary units don’t follow a tidy power of ten — each pair has its own factor, so these are mostly worth memorising. The good news is there aren’t many.
- Length: 1 ft = 12 in, 1 yd = 3 ft.
- Weight: 1 lb = 16 oz.
- Capacity: 1 gal = 4 qt, 1 qt = 2 pt, 1 pt = 2 cups.
To convert to a smaller unit, multiply by the factor; to a larger unit, divide.
Worked examples
Tips & common mistakes
A memory aid for capacity is “gallon man”: a gallon holds 4 quarts, each quart 2 pints, each pint 2 cups. Once the factors are memorised, converting is just multiplication or division. Type the number.
- Using a metric-style factor of 10 — customary factors are 12, 3, 16, 4, 2.
- Forgetting which way to go — smaller unit means multiply.
- Mixing up the capacity ladder (gallon → quart → pint → cup).
Frequently asked questions
What are the main customary conversions?
1 ft = 12 in, 1 yd = 3 ft, 1 lb = 16 oz, 1 gal = 4 qt, 1 qt = 2 pt, and 1 pt = 2 cups.
How do you convert customary units?
Multiply by the factor to get a smaller unit, divide to get a larger one. 2 feet is 2 × 12 = 24 inches.
Why are customary units harder than metric?
Because each conversion has its own factor (12, 3, 16, 4…) instead of a consistent power of ten, so they have to be memorised.
What is the capacity order?
From largest to smallest: gallon, quart, pint, cup — each step is a factor of 2 except gallon to quart, which is 4.
What grade is this?
Customary unit conversion is a grade 4–6 measurement skill.