There is a very simple reason why this the best Metric/American Imperial unit converter: I made it for my own personal use and included all the tiny conveniences I could think of, favoring simplicity and ease of use above all else. There isn't even a "Convert" button - the result is shown as you type!
The converter includes all the units in common every-day use and nothing more. You don't need to scroll through complex menus full of arcane units you've never heard of. All the conversions are literally a tap away.
The most common units are the ones causing the most confusion. Fahrenheit to Celsius, kilograms to pounds, that sort of thing. Who needs to convert mmHg to psf anyway? (No, I don't know what that is either)
The conversions included are: Fahrenheit to/from Celsius Feet to/from meters Inches to/from centimeters X' Y'' notation to/from meters and centimeters Miles to/from kilometers Pounds to/from kilograms Ounces to/from grams Fluid ounces to/from millilitres Gallons to/from litres Miles per gallon to/from litres per 100km Acres to/from decares Square and cubic feet and meters