compensate weight due to acceleration (loadcells)
The force due to acceleration is: F = m*a
So to calculate the weight while accelerating the formula is:
F = mg + ma or F = m(g + a)
Note, of course, that a can be positive or negative depending on whether the elevator is accelerating or decelerating.
The trick here is to know what &quot;a&quot; is.  The best approach is probably to get an accelerometer and use its reading in your calculations.
By the way, the mass is always a constant here.  It does not change, in Newtonian Physics at least, due to acceleration.