Am I inputting things right? it's showing 100%

[dvalley]

I chose $50k annual spend. 35 yrs of retirement. Current portfolio $550k, will add approx $40k each year until retirement date say 2025. SS starting in 2034 totaling $20k per year.

FIRECalc Results
Your spending in every year after the first year will be adjusted for inflation, so the spending power is preserved.
Because you indicated a future retirement date (2025), the withdrawals won't start until that year. Your contributions will continue until then. The tested period is 8 years of preretirement plus 27 years of retirement, or 35 years.
FIRECalc looked at the 112 possible 35 year periods in the available data, starting with a portfolio of $550,000 and spending your specified amounts each year thereafter.
Here is how your portfolio would have fared in each of the 112 cycles. The lowest and highest portfolio balance at the end of your retirement was $87,569 to $8,479,580, with an average at the end of $2,651,282. (Note: this is looking at all the possible periods; values are in terms of the dollars as of the beginning of the retirement period for each cycle.)
For our purposes, failure means the portfolio was depleted before the end of the 35 years. FIRECalc found that 0 cycles failed, for a success rate of 100.0%.

[dvalley]

Ah I see what might be the problem, I think I need to input 43yrs (35yrs of retirement and 8yrs of pre-retirement). Even so it's showing 98%. I thought I was way off track.

[flyingaway]

In my opinion, FIRECalc result is usually close to the 4% rule. Your result looks fine.

[dvalley]

Thanks, it's just that Personal Capital's retirement planner (also Monte Carlo based I think) gives me very different results (48% or so success rate) with similar numbers.

[SecondCor521]

Monte Carlo simulations generally give lower success rates than historical calculators, which in turn give lower success rates than static analysis calculators. It's up to you to learn about the assumptions behind the calculators you use and decide if you feel comfortable with those assumptions and whether or not they apply to your particular situation.

[exnavynuke]

with $550k now, 8 years of growth (without any additional contributions) at 7% would be $945k in 8 years. Add in $320 worth of contributions and that's $1.265M. $1.265M at 4% would give $50.6k/year at 4%. Of course, that doesn't factor into account inflation between now and then (a negative) or the growth of your contributions over the next 8 years (a positive) or SS (a positive). So it seems to me that the numbers make sense.