Paul's Retirement Planning Script

Welcome to Paul's retirement planning script! The focus of this tool is to enable Paul and perhaps others in similar situations to do coarse lifelong financial planning with less need to "bring your own assumptions."

Wealth

This plot shows how your wealth could grow until retirement in several scenarios ranging from pessimistic to optimistic. It automatically calculates the earliest time that you could retire.

Deltas

This plot shows where your money might come from and go to each year in a median scenario.

Get Started

All numbers, e.g. salary should be post tax

All calculations are done in current-year dollars, without incorporating inflation. For example, if it says that you'll have $1M in 2050, that's $1M 2023 dollars; it would likely be closer to $2M 2050 dollars.

How It Works

We forecast multiple future "universes" with different levels of "optimism," which means like "optimism about the economy." This aims to solve a big problem with a naïve Monte Carlo implementation, which is that independently simulating many different events will underestimate the variation among possible scenarios. For example, if the stock market goes down, that probably decreases the likelihood that you'll get a raise and probably decreases the value of your home. Instead, each future universe has an "optimism" value between 0 (pessimistic) and 1 (optimistic), and we deterministically derive values for all uncertain parameters from this value. So, instead of assuming a correlation of 0 (perfect independence), this assumes a correlation of 1 (perfect dependence). I haven't thought much about the tails so the modeling of scenarios outside of the optimism range of 0.1–0.9 are definitely not going to be modeled well.

Key inputs:

Major things modeled:

Current biggest risks:

  1. Uncertainty about big questions like human lifespan, college tuition, interest rates, social security, property values, and interest rate variability
  2. Poor documentation and minimal input validation could cause errors
  3. Just straight up bugs
  4. Simplifications around things like taxes and social security

Attempt at legal disclaimer

This program does not constitute advisement to invest in, buy, or sell securities.