Customary & Metric Measurement Conversions Cheat Sheet

Key Facts

• To convert larger units to smaller units, multiply by the conversion factor, such as $3\text{ ft} \times \frac{12\text{ in}}{1\text{ ft}} = 36\text{ in}$.
• To convert smaller units to larger units, divide by the conversion factor, such as $48\text{ oz} \div 16 = 3\text{ lb}$.
• Common customary length conversions include $1\text{ ft} = 12\text{ in}$, $1\text{ yd} = 3\text{ ft}$, and $1\text{ mi} = 5280\text{ ft}$.
• Common customary weight conversions include $1\text{ lb} = 16\text{ oz}$ and $1\text{ ton} = 2000\text{ lb}$.
• Common customary capacity conversions include $1\text{ cup} = 8\text{ fl oz}$, $1\text{ pt} = 2\text{ cups}$, $1\text{ qt} = 2\text{ pt}$, and $1\text{ gal} = 4\text{ qt}$.
• Metric prefixes follow powers of $10$: $1\text{ km} = 1000\text{ m}$, $1\text{ m} = 100\text{ cm}$, and $1\text{ cm} = 10\text{ mm}$.
• Metric mass and capacity conversions include $1\text{ kg} = 1000\text{ g}$, $1\text{ g} = 1000\text{ mg}$, and $1\text{ L} = 1000\text{ mL}$.
• A conversion factor must place units so they cancel, such as $5\text{ m} \times \frac{100\text{ cm}}{1\text{ m}} = 500\text{ cm}$.

Vocabulary

Customary system

The measurement system commonly used in the United States, including inches, feet, yards, miles, ounces, pounds, cups, pints, quarts, and gallons.

Metric system

A base-ten measurement system that uses units such as meters, grams, and liters with prefixes like kilo-, centi-, and milli-.

Conversion factor

A ratio equal to $1$ that compares two equivalent measurements, such as $\frac{12\text{ in}}{1\text{ ft}}$.

Unit

A label that tells what kind of measurement is being used, such as $\text{cm}$, $\text{lb}$, or $\text{gal}$.

Prefix

A word part in the metric system that shows the size of a unit, such as kilo- meaning $1000$ and milli- meaning $\frac{1}{1000}$.

Dimensional analysis

A method of converting measurements by multiplying by conversion factors so unwanted units cancel.