I think you will find the calculation to be a exercise in futility.
While theoretically it may be accomplished if the mfg of the LED provides enough information. However the information I've seen on "name brand" LEDs is only a nominal and they are very nonlinear.
I think you would be best setting up a small circuit with an LED and Resistor. Vary either the voltage or resistor, then calculate the proper resistor for the target voltage.
Good luck.