Hi. MDM posted this formula on another thread to estimate time to FI. I've tried plugging my numbers into excel but it spits out a -.87. Clearly, I am doing something wrong, but I'm not sure what. Could someone help me please?

The formula was....Time in years to FI = Ln((S + i*E/WR) / (S + i*A)) / Ln (1+i)

Where A = Asset amount currently invested in funds to be drawn in retirement (525k for me)

E = Total annual expenses in retirement, including taxes (estimating 40k for me)

i = Real return on invested retirement funds (Which I'm assuming is return less inflation? I was assuming 3%)

S = Annual amount invested in funds to draw on in retirement (Which I assume is my contributions to retirement funds, = 21k for me now)

WR = Withdrawal rate = 4% for me

TIA.

-Casey