After you enter the column number and fuel type, a slider will appear. Swipe to the right to choose to fill up to a full tank.
By default, we consider a tank of 50 liters as a full tank. If you have it more or less, click on the "Edit" button and specify the volume. You need to do this once - the application will remember your tank volume.
In addition, you can change the volume of a full tank in the Menu by selecting the “Full tank” item.