I’m a huge fan of Soulver, a scratchpad for doing calculations and unit conversions of all kinds. It’s great for things that aren’t complex enough to need a spreadsheet, but are too fiddly for a standard calculator. This is what it looks like:
I maintain that anyone who is doing any math on their Mac or iOS device should have Soulver open at all times. I’m not the only one.
But what about people on Windows or who want to use a web browser? I was hoping this thread on Hacker News would surface some good options, but none of the suggestions I tried were as well-designed, well-maintained, or usable.
SpeedCrunch was the one suggestion that looked interesting – it’s open source and available on Linux, Mac, and Windows (not mobile though). The design differs from Soulver but the basic idea is the same. Unfortunately the Mac version is not signed with a developer certificate so I’m not comfortable installing it on my computer. If you are braver than I, let me know how it works.