Web: If you're in a new country and unsure of how much you should tip, head to Tip This Much to find out. The web app works perfectly on desktop as well as mobile.
Tip This Much will automatically detect your current country based on your IP, but if it gets that wrong, you can change it quickly. It will then tell you the range for a good tip, which you can use with the bill calculator when you scroll down. Put in your amount, choose the tip amount, enter how many people to split it with, and there you have how much everyone owes. Quick and easy.
The app is far easier than referencing an infographic on global tipping practices, but it's restricted to food bills and tips.