Retirement Lab is a fast experiment lab for US retirement tradeoffs. Start with a US baseline, change one assumption at a time, and watch the simulated outcome move across 10,000 Monte Carlo paths with US federal and state tax modeling baked in.
Run a US scenarioExample experiment — the simulation shows how the same baseline plays out at three retirement ages:
Numbers are illustrative. The simulation shows what happens when only the retirement age changes.
Search visitors usually arrive with one concrete US retirement question. These are the experiment lanes the page is built around — each maps to an input you can change in the simulator, not to a feature that promises an answer.
The free tier runs the experiment loop end to end. You can build a US baseline, flip a single assumption with Explore a Change, run a single sweep, and put two scenarios side by side in compare mode without an account. Saved scenarios, the year-by-year ledger, and the full US tax detail stay free because they are how you check the simulator’s work.
Pro unlocks the deeper planning loops once a baseline feels trustworthy: full multi-variable sweeps, advanced withdrawal strategies such as guardrails and other adaptive rules, Roth conversion exploration, PDF and CSV exports, and higher-resolution simulations. See pricing for the full breakdown. Either tier stays within the calculator scope: simulated outcomes for the inputs you set, not personalized planning.
Set residency state, ages, current balances, and target spending. The simulator runs 10,000 Monte Carlo paths with US federal and state tax modeling and shows the starting fan chart and simulated success rate. Free, no account required.
Use Explore a Change to flip a single assumption (age, spending, residency, portfolio risk), or run a sweep across a range of values to see how the simulated outcome bends. Change one lever at a time so you can read the effect cleanly.
Open compare mode to put two scenarios side by side, or drill into the scenario detail ledger for year-by-year cash flow and US tax detail. Inspect what moved instead of trusting one summary number.
The page is built for US planning workflows — US federal tax modeling, state-tax residency, Social Security claim age as a scenario input, and ACA / Medicare / IRMAA-sensitive years are first-class concerns. The same simulator also covers a wider set of residency countries if you want to model an international move; the methodology page documents the country coverage and the assumptions behind each tax module.
Each simulated year applies bracket-based US federal income tax to taxable withdrawals, capital-gains tax to realized gains, and the state-tax rules for the residency state you choose. The after-tax cash you can spend in a given year reflects the bracket the simulated portfolio puts you in that year, the way real US taxes work — not a flat haircut. US tax modeling is intentionally simplified: published bracket schedules and standard deductions, not every edge case (AMT, NIIT thresholds, every state-specific surtax). Treat results as a directional simulation, not a tax return.
Yes — as scenario inputs you control, not as automated optimization. You can pick a Social Security claim age, set Roth conversion amounts and timing, and read the year-by-year ledger to see how MAGI moves and where ACA subsidy phaseouts or Medicare IRMAA brackets bite. The simulator shows the simulated outcome of those choices; it does not pick a specific strategy for you.
The FIRE calculator applies the same simulator to financial-independence targeting, and the Monte Carlo retirement simulator page goes deeper on the simulation method (fat-tail-aware returns, percentile bands, sequence risk). This page is the US planning entry point: same engine, framed around the experiment loop a US visitor arrives with — “what changes my retirement odds?”