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Retirement & FIRE Calculators

Calculators for the longest-horizon problem in personal finance β€” how much you need, how long it lasts, and when you could stop working.

The two variables that decide everything

Retirement planning has more inputs than any other calculation here, but two dominate the outcome: how early you start, and what inflation does to your expenses along the way.

Starting early matters more than contributing heavily. Someone investing a modest amount from age 25 routinely ends with a larger corpus than someone investing far more from age 40, because the first person has fifteen extra years of compounding on every contribution. Those early years feel insignificant while you are living them and turn out to be the most valuable ones.

Inflation is what makes retirement numbers counterintuitive. A monthly expense of 50,000 today becomes roughly 160,000 in 20 years at 6% inflation. Any calculation that ignores this β€” and many rules of thumb do β€” will understate the required corpus by a factor that is not recoverable once you notice.

The FIRE calculator approaches the same problem from the withdrawal side, asking what corpus supports your spending indefinitely. The commonly cited 4% rule derives from a specific US historical dataset and is a reasonable starting point rather than a law of nature. Test your plan against a more conservative withdrawal rate before you rely on it.