Quickly Convert Currency and Measurements
Spotlight is also great for quick conversions. You can convert currencies using real-time data from Yahoo Finance, or any number of popular units, like miles, kilometres, pounds, grams, cups, teaspoons, and more.
Simply call up Spotlight and enter the number you want to convert, followed by the unit you want to convert from. Spotlight will offer the most common conversion result — for example, if you enter miles, you’ll get the result in kilometres — and on macOS, a few alternative units will be shown as well in the preview panel, and on either platform you can specify the target unit with “in” or “to,” for example, typing “10 km in feet” or “5 cups in tsp.”
Spotlight supports most common units of measurement, even right down to things like calories and joules. but if you’re looking to convert more esoteric values like ergs and furlongs, you’ll need to turn to a specialized app, or simply enter the result in Spotlight and press enter to open a web search for the result — most search engines will be happy to help you right in the results with just about any unit out there.