# Retirement Lab

> Monte Carlo retirement simulator. Model portfolio outcomes with fat-tail risk, historical stress testing, dynamic spending rules, and correlated asset returns.

Retirement Lab is a SaaS retirement simulation tool that runs Monte Carlo simulations to help users project retirement outcomes. It features Student's t-distribution with Fernandez-Steel skewness for fat-tail modeling, historical stress testing against 97 years of real US market returns (1928-2025), Guyton-Klinger dynamic spending rules, correlated asset returns via Cholesky decomposition, and flat-rate tax calculation. Built by an independent software engineer in Switzerland.

## Pages

- [Home](https://retirement-lab.com/): Product overview, features, and call-to-action
- [Pricing](https://retirement-lab.com/pricing): Free and Pro tier comparison with FAQ
- [Learn](https://retirement-lab.com/learn): Educational articles about retirement planning
- [Glossary](https://retirement-lab.com/learn/glossary): 50+ retirement and investment terms (A-Z, searchable)
- [About](https://retirement-lab.com/about): Mission, values, and product philosophy
- [Contact](https://retirement-lab.com/contact): Contact form and support
- [Terms of Service](https://retirement-lab.com/terms): Legal terms of use
- [Privacy Policy](https://retirement-lab.com/privacy): Data collection, Swiss FADP and GDPR compliance
- [Legal Disclaimer](https://retirement-lab.com/disclaimer): Simulation limitations and legal disclaimers

## Pricing

### Free (forever)
- 1,000 Monte Carlo iterations per run
- 2 saved simulations
- Multi-asset portfolio with Cholesky correlation
- Income streams and expense modeling
- Fixed-amount withdrawal strategy
- Portfolio fan charts and simulation history
- Side-by-side simulation comparison

### Pro ($29/year or $79 lifetime)
- 50,000 Monte Carlo iterations per run
- 5 saved simulations
- Fat-tail distributions (skewed Student's t with Fernandez-Steel)
- 4 withdrawal strategies: fixed amount, Guyton-Klinger, percentage of portfolio, floor & ceiling
- Black swan event modeling at specific ages
- Historical stress test: drag across 97 years of real S&P 500 and Treasury returns (1928-2025)
- Sequence-of-returns risk heatmap
- PDF reports and priority support
- 30-day money-back guarantee
- Yearly: billed annually, cancel anytime. Lifetime: one-time payment, yours forever.

## Key Features

- **Monte Carlo engine**: Pure TypeScript, deterministic via seeded PRNG, DOM-free
- **Fat-tail modeling**: Student's t-distribution with configurable degrees of freedom and Fernandez-Steel skewness parameter (Pro)
- **Dynamic spending**: Guyton-Klinger guardrails with configurable cut/boost percentages (Pro)
- **Correlated returns**: 3x3 Cholesky decomposition for stocks, bonds, and alternative assets
- **Historical stress test**: Interactive sliding window across 97 years of real US market returns (S&P 500 + 10-Year Treasury, 1928-2025) with historical success rate (Pro)
- **Black swan events**: One-time portfolio drops at user-specified ages (Pro)
- **Withdrawal strategies**: Fixed amount, percentage of portfolio, floor & ceiling, Guyton-Klinger
- **Multi-phase allocation**: Age-banded stock/bond/alternative asset allocation
- **Income streams**: Social security, pensions, rental income with start/end ages
- **Irregular cash flows**: One-time contributions and withdrawals at specific ages
- **Simulation comparison**: Select any two saved simulations and compare key metrics, overlaid projections, and parameter differences side by side
- **Tax modeling**: Flat effective tax rate on withdrawals

## FAQ

- **Is there a free trial?** No trial needed; the Free plan is free forever. Pro has a 30-day money-back guarantee.
- **What are fat-tail distributions?** They model extreme market events (crashes/booms) more realistically than a normal bell curve, using Student's t-distribution.
- **What is Guyton-Klinger?** A dynamic withdrawal strategy that automatically cuts or boosts spending based on portfolio performance relative to guardrails.
- **How accurate are simulations?** Results are probabilistic projections, not predictions. Accuracy depends on user-provided assumptions for returns, volatility, and expenses.
- **Can I downgrade from Pro?** Yes, you keep access until the billing period ends. Simulations beyond the free limit become read-only.

## Who Is This For?

- People planning for retirement who want data-driven projections beyond simple calculators
- DIY investors who want to stress-test their portfolio against fat-tail risks and market crashes
- Financial independence / FIRE community members modeling early retirement scenarios
- Anyone who wants to understand how withdrawal strategies, asset allocation, and market volatility affect retirement outcomes

## How It Compares

Unlike basic retirement calculators that use fixed average returns, Retirement Lab uses Monte Carlo simulation with advanced statistical modeling (fat tails, correlated returns, dynamic spending rules). It shows the full range of possible outcomes rather than a single projection, helping users understand the probability of success under different market conditions.

## App

The authenticated application is at [app.retirement-lab.com](https://app.retirement-lab.com). Users sign up there to run simulations, save projections, and manage settings. Sign in with Google is available.

## Notes

- Simulation results are not professional advice. All projections are probabilistic and based on user-provided assumptions.
- The simulation engine is pure TypeScript with no external dependencies, designed for deterministic output via seeded PRNG.
- Data is stored in Supabase (PostgreSQL) with row-level security. All user data is isolated per account.