@mllcb42 Thank you for the incredibly helpful resource! Posting them on the Calculator page as Calculator 101!
Hi thank you for your informative post. However I am getting a very large difference in my monthly payments when I calculate it manually vs when I use the calculator. Can you let me know if the formula I am using is correct? Or if I just have a misunderstanding on how to calculate leasing price.
Monthly Payment (excluding tax and interest) = [ (The Agreed Sell price of the car)  (MSRP * RV ) ] / Months of Car being lease. Then once you get the Monthly Payment multiply it by the (MF * 2400)/100 to calculate what monthly payment would be including interest.
This example is excluding down payment and Taxes.
Example is A car with MSRP 100,000, dealer agreed to lease at 90,000 ( 10% cap reduction), 36 months 10,000 miles/yr with MF 0.00200 and RV 60%. When I used the lease hacker calculator plugging those values I get a PreTax Monthly Payment of 1,157.
However when I do it manually I get: 100,000 * .60 = 60,000 RV. 90,00060,000 = 30,000 of deprecation 30,000/36 = 833.33 a month * (0.00200 * 2400)/100 = 39.99 of interest per month
Total PreTax Monthly Payment is 833.33 + 39.99 = 873.32.
Am I doing something wrong? That is a huge difference from 1,157 to 873.32. Total of 10,212 dollars over 36 months. Sorry for the long post. If anyone can help I would greatly appreciate it. Thanks
You’re missing a couple critical parts in your calculations here:

The depreciation amount is the delta between your adjusted cap cost and the residual value. That generally means agreed on price  incentives + upfront taxes and fees. Those taxes and fees are often not an insignificant amount.

Your rent charge amount is way off.
Monthly rent charge = MF * (adjusted cap cost + residual value)
I’m the case of your .002 MF example, your monthly rent charge would be .002*(90000+60000)=300
There is an article on the LH website explaining this.
“How to calculate payments by hand”
Question for LH Calculator  do we modify the sales tax or is that set at 9%? Texas sales tax is 6.25%.
Set it to your tax rate
When people start asking how to work the calculator and what the numbers mean, I think you should just start linking this.