If you increase the withdrawal percentage you need a smaller amount to "support" your retirement, so the years to retirement gets smaller. This model does not appear to say anything about how many years of retirement you will have. A higher withdrawal percentage very likely means you have a shorter retirement, which in turn likely means you run out of money. You should just leave the percentage set at 3-4% and use a different model (on another site - they don't appear to have another one here) to figure out the whole picture. Or consider using a different model somewhere else in the first place. Fidelity or Vanguard or Bank of America or ...(the list is long) have better retirement calculators.

Yeah, this doesn't make sense. If you withdraw more, it lasts less. Setting the withdraw percent to 100% would deplete your savings after only 1 year.

If I need 50,000k a year at 3% I need 1.5 million. at 4% I need 1.25 million.

By increasing the percentage you need less money. However it is more risky to withdraw each year