Around 2 hours.
When it is full charged, the indicator turns green.
1. Please charge it with your home supply directly through a 5V-output adapter or a 5V-output power bank. Sometimes it CANNOT be charged by PCs.
2. Please make sure your adapter outputs 1A-2A. Many fast chargers might over-output.
3. Most of Apple’s 2.4A adapters work.
credit: Thanks to Alex Gismo for the last pic.