Just tell us your current annual living cost, current annual savings amount, and current savings.

E.g. $30K, $50K, $200K.

Then, we see you need 25x30k to retire = $750k, which is $550k more than you have. You could save that much outright in about ten years, but with 7.2% returns you'll get there in about seven.

NPER(7.2%,-50,-200,750)=6.8 years.

There is no monte carlo or probability involved - this is deterministic. If the market does better you will get there sooner. If it does poorly, it will take longer.

The success rate you get from the simulators is the success on living a specified number of years on your specified savings and withdrawals without running out of money. At 4% SWR most simulators will give you 90% chance of the money lasting 30 years.