I ran across this formula, how accurate/legit is it?

http://www.edmunds.com/car-loan/calc...e-payment.html

 

When I leased cars, I used this one and it matched what the dealer calculated to the penny - except when they were trying to pull a fast one.

http://www.leaseguide.com/calc.htm

These days, I would find one that ran on my iPad and go in fully armed.

 

You can just use excel using the PMT function, enter in your period, APR/period, set the PV to the current value of the lease / car, and FV to either 0 or residual.

It gives you the same result minus the interest vs principal payment table.