How long until you reach your goal?
Projection with monthly compounded interest.
What passive income can a capital generate?
What the capital can pay annually without eroding.
The 4% rule assumes withdrawing 4% of the capital in the first year: historically, a diversified portfolio could sustain this rate over 30 years. This is not a guarantee.
The capital is compounded monthly. Each month, the existing capital is multiplied by the monthly rate (annual return divided by 12), then the monthly payment is added. This is the standard calculation of compound interest with regular payments.