Unit Conversions

To convert units, multiply by a conversion factor — a fraction equal to 1: [formula] Example: Convert 5 feet to inches. [formula] The key: the old unit cancels out, and you're left with the new unit.

Example: Convert 90 kilometers per hour to meters per second.

The SAT provides a reference sheet, but knowing these speeds things up: Length: 1 ft = 12 in, 1 yd = 3 ft, 1 mi = 5,280 ft, 1 km = 1,000 m, 1 in approx 2.54 cm Volume: 1 gal = 4 qt, 1 L = 1,000 mL Weight: 1 lb = 16 oz, 1 kg approx 2.2 lb Time: 1 hr = 60 min = 3,600 s