Using this calculator is fairly simple. You type in what you're converting from in the first box, and what you want to convert to in the second box. It's best explained with a few examples.
You have: meters You want: inches Answer: meters = 39.370079 inches
You have: (1/4) cup You want: teaspoons Answer: (1/4) cup = 12 teaspoons
You have: 16 miles / gallon You want: rods / hogshead Answer: 16 miles / gallon = 322559.35 rods/hogshead
Want to know how far away that lightning was? You have: 15 seconds * mach You want: miles Answer: 15 seconds * mach = 3.0893954 miles
Note that conversions that are more complex than simple ratios require a different syntax. Refer to the data file for names and details. You have: tempF(200) (captialization matters here!) You want: tempC Answer: tempF(200) = tempC(93.333333)
How much does 3 inches of freshly fallen snow weigh down a 1-mile long train with 10-foot-wide cars. Fresh snow weighs 10 lbs per cubic foot (source). You have: (10 lbs/ft^3) * 1 mile * 10 feet * 3 inches You want: tons Answer: 66 tons