3E Measurement Conversions Study Guide

📘 Key Vocabulary

Convert — to change from one unit of measurement to another. (convertir)

Customary System — the measurement system used in the United States (inches, feet, pounds, gallons). (sistema inglés)

Metric System — the measurement system used in most of the world (meters, liters, grams). (sistema métrico)

Ratio Table — a table used to organize conversion factors and find equivalent measurements. (tabla de razones)

Unit — a standard amount used to measure (inch, foot, meter, cup, etc.). (unidad)

📋 Common Conversions Reference

Customary (U.S.) Length

From	To	Multiply by
1 foot (ft)	12 inches (in)	× 12
1 yard (yd)	3 feet (ft)	× 3
1 mile (mi)	5,280 feet (ft)	× 5,280

Customary (U.S.) Capacity

From	To	Multiply by
1 cup (c)	8 fluid ounces (fl oz)	× 8
1 pint (pt)	2 cups (c)	× 2
1 quart (qt)	2 pints (pt)	× 2
1 gallon (gal)	4 quarts (qt)	× 4

Metric Length

From	To	Multiply by
1 kilometer (km)	1,000 meters (m)	× 1,000
1 meter (m)	100 centimeters (cm)	× 100
1 centimeter (cm)	10 millimeters (mm)	× 10

Metric Mass

From	To	Multiply by
1 kilogram (kg)	1,000 grams (g)	× 1,000
1 gram (g)	1,000 milligrams (mg)	× 1,000

🔢 Step-by-Step — Using a Ratio Table to Convert

1 Write the conversion factor as a ratio (example: 1 foot = 12 inches).
2 Set up a ratio table with the known and unknown values.
3 Multiply or divide both parts by the same number to find the answer.
4 Label your answer with the correct unit!

Example: Convert 5 feet to inches.

Conversion: 1 foot = 12 inches

Feet	1	2	3	4	5
Inches	12	24	36	48	60

Or simply: 5 × 12 = 60 inches

Example: Convert 3,000 meters to kilometers.

Conversion: 1 km = 1,000 m → going from smaller to bigger, so divide.
3,000 ÷ 1,000 = 3 kilometers

📐 Formula Box

Bigger unit → Smaller unit = MULTIPLY by the conversion factor

Smaller unit → Bigger unit = DIVIDE by the conversion factor

💡 Memory Tip

Going to a smaller unit? The number gets BIGGER (more small pieces). Multiply.

Going to a bigger unit? The number gets SMALLER (fewer big pieces). Divide.

2 feet → ? inches (smaller unit) → 2 × 12 = 24 inches (bigger number)
36 inches → ? feet (bigger unit) → 36 ÷ 12 = 3 feet (smaller number)

⚠️ Watch Out!

Don't mix up multiply and divide! Remember: smaller unit = multiply, bigger unit = divide.
Metric is based on 10s (10, 100, 1000). Customary uses different numbers (12 inches/foot, 3 feet/yard, 4 quarts/gallon).
Always include the unit in your answer! "60" is incomplete. "60 inches" is correct.
Don't convert between systems unless given a conversion factor. You need to know the exchange (e.g., 1 inch = 2.54 cm) to go between customary and metric.

✏️ Practice Problems

Type just the number (no units needed).

1. Convert 4 yards to feet. (1 yard = 3 feet)

2. Convert 3 gallons to quarts. (1 gallon = 4 quarts)

3. Convert 5,000 meters to kilometers. (1 km = 1,000 m)

4. Convert 6 pints to cups. (1 pint = 2 cups)

📏 3E | Measurement Conversions Study Guide