Hi all,
I've released a simple, intuitive app on the play store to help drone enthusiasts predict how long their multi-rotor will fly before they actually purchase the components, just plan. This is very accurate while taking into consideration the most important parameters.

Here is the link: https://play.google.com/store/apps/details?id=com.justrobotics.android.uavuptimecalculator

Hope you find this useful.

Good start, but what about the number of cells in the LiPo?

A 4S 1500mah and 6S 1300mah would give different flight times, all other parameters being same, including AUW.

That's taken care of by maximum amps and thrust.
A motor which works with both 4S and 6S would have different amp requirements and thrust delivered, and there are fields for that. Number of cells does affect flight time, but only indirectly.