Retirement flips the math: instead of growing the pile, you are defending it — against inflation, against bad timing, against outliving it. These tools model the defense honestly.
The classic 4% rule suggests savings last ~30 years if you withdraw 4% of the starting balance annually, adjusted for inflation. Model your own numbers with the compound interest calculator: enter your balance, a negative-equivalent scenario via the inflation tool, and your real return (market return minus inflation).
Quietly halves it: at 3% inflation, a $3,000/month pension buys what $1,660 buys today after 20 years. The inflation calculator shows the erosion curve — it is why even "safe" fixed income needs a growth component.
Compare guaranteed vs expected return: paying it off earns your mortgage rate risk-free. If your rate is 6%+ and your portfolio is conservative, payoff often wins. The loan payoff calculator shows the interest saved; the peace of mind is free.