If usage and standby are equal it means there is a process on your phone that is running continuously. If you power cycle the phone (turn it off, wait a minute, then turn it on) this will kill all processes and should fix the problem. If it doesn't you have an app with corrupt data and you will have to track it down.
Note that the battery percentage in Settings/battery does not show the percentage of total battery capacity. It shows what each app has used out of the total used, and it is also based on 24 hours. It does not take into consideration any recharges, either. As a simple example, suppose you charged your phone 24 hours ago, and it now shows 50% on the Home screen. And an app shows 40% in Settings/battery. That's 40% of the 50% of usage, or 20% of the total usage since the last charge. But if you have charged it within the past 24 hours there is no way to relate the values in Settings/Battery with actual energy. These numbers are only to compare apps with each other, not to determine how much battery any one app has used.
iPhone 7 battery usage vs standby is the same.
