Calculators that show their work.

Available tools

• Available nowRetirement

  Monte Carlo Retirement Calculator

  Run 10,000 simulations of your retirement plan in your browser. See how often the plan survives, what the bad cases look like, and where the assumptions matter most.

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• Available nowFIRE

  FIRE Calculator

  Translate your annual spending into a financial-independence target with a valuation-aware safe withdrawal rate. Runs entirely in your browser.

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• Available nowRetirement

  Bucket Strategy Planner

  Plan and stress-test a two-bucket retirement withdrawal strategy — a stability bucket funds spending, a growth bucket refills it — with research-backed guardrail rules, Monte Carlo success rates, and a January-2000 dot-com stress test.

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• Available nowOptions

  Options Strategy Builder

  Build multi-leg option strategies — spreads, condors, straddles, calendars — and see profit and loss at every price and every date between now and expiry, with Greeks, breakevens, probability of profit and a payoff chart.

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• Available nowOptions

  Options Calculator

  Breakeven, maximum profit and loss, and return for four single-leg strategies — buying calls and puts, selling cash-secured puts and covered calls — with a payoff chart and an at-expiration scenario table.

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• Available nowInvesting

  Investment Calculator

  Project how contributions and compounding grow an investment — or solve for the contribution, return, starting amount, or time you need to hit a goal. Compare scenarios side by side.

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• Coming soonReal estate

  Rental Property ROI

  Run the numbers on a rental — cash flow, cap rate, and long-run total return — before you commit.