Most retirement calculators seem built around a 30 year horizon, which makes sense for traditional retirement but feels a little disconnected if you’re thinking about stopping work much earlier like in your mid-30s.

This calculator is meant for people planning very long retirements, like 40 or 50 years. You can plug in a portfolio size, a withdrawal rate, expected market returns, and inflation, and then see how things play out over a longer timeline.

It also shows income in today’s dollars, which helps make it clearer how much of the future “growth” is just inflation doing its thing.

It’s not perfect but it's a good way to sanity-check assumptions (especially your safe withdraw rate) for early retirement.