A small power bank is easy to bring in your pocket or bag to charge your smartphone on the go. These mini power banks are usually no larger than 10 by 6cm. To illustrate, most new smartphones are 15 by 7cm on average. Power banks are often slightly thicker, but if your smartphone fits in your pocket, a small power bank will likely also fit. These power banks come in handy if you quickly want to charge your smartphone at the end of a day trip. Most small power banks have a 5000mAh capacity. This is either just enough or just short of 1 full charge, depending on the size of your battery. With 10,000mAh capacity, you can charge most smartphones 1 to 2 times.