Camera Exposure Calculator app allows you calculate the perfect exposure for your photography.
You just have to input your current exposure (Aperture shutter speed and ISO) and it will automatically calculate the exposure based on your new settings.
It supports to add an ND filter until 30 stop.
The apps displays the current EV and integrates a chronometer to help you calculate a perfect exposure.

Source code can be found here:
https://github.com/awoisoak/Camera-Exposure-Calculator

Icons from:
https://openclipart.org/