Research shows that people generally hold their phone in one-hand, using their thumb as the primary navigation tool. Therefore, it is essential to ensure your mobile design is catered, if not optimised, for thumb usage and ergonomics. Ideally, you would want to test the ergonomics of a mobile design with a range of devices and screen sizes but this is not always possible due to time and budget constraints. As an alternative, you can copy and paste these Thumb Zone diagrams on top of your design to check if the main content and functionality are placed within the easy-to-reach zone across devices.
You can also check images on here - http://imgback.io/