It still baffles me why we have so many different units of calculations. The World would be much less annoying if we all used one system of measurement.
Until that day comes, you'll just have to settle with using an app such as Converter Touch to calculate what the amount of one unit equates to in another unit. This program is one of the more user-friendly ones I've tried, and makes good use of the touch functionality of Series 60 5th Edition devices.
All you need to do is select a type of measurement from the scrollable icon tray at the top of the interface. Converter Touch supports units of measurement for weight, temperature, volume, distance, speed, power, and more. Next, you select the unit of measurement you want to convert to and from just by tapping on it. Now, just tap in the amount using the touchpad and the conversion will be automatically be displayed as you type.
Unfortunately, I did experience some problems when using Converter Touch. The sliding icon tray does feel a bit unresponsive and it often freezes up for a few seconds while you're trying to scroll along it. I also had some display issues during testing, but hopefully these are glitches that the developer will iron out over time.
If you're looking for a way of quickly converting one unit to another though, Converter Touch is a powerful solution.