How is converting a metric measurement to a metric measurement similar to and different from converting a metric measurement to a US Customary measurement?

Answer 1

Similarities: converting between any two units (of the same dimension) simply requires a conversion factor. Example:

• 1 inch = 2.54 centimeters
• 1 meter = 100 centimeters
• 1 foot = 12 inches

To convert from inches to centimeters, simply multiply by 2.54. To convert from meters to centimeters, simply multiply by 100. Each unit has a conversion factor with centimeter. Similarly, any unit will have a conversion factor with another unit (of the same dimension).

Note that all of the units in the above example are length units. You cannot convert from volume to length, or mass to temperature, for example.

To convert the other way (from centimeters to inches), you need to divide both sides of the equation above by 2.54:

• 1/2.54 inch = 1 centimeter --> 0.39370 inch = 1 centimeter

so you can now either multiply by 0.39370 or divide by 2.54

So the main difference is that in the metric system, all of the conversion factors will be powers of ten, and you can derive what power of ten to use from the prefixes. Centi- is always 100 (a centi-something is always 1/100 of the base unit). So there are 100 centigrams in a gram, 100 centimeters in a meter, 100 centiliters in a liter.

In the customary system, you must know (or look up) the necessary conversion factor (12 inches in 1 foot, for example).