← Back to Docs

Retirement Calculator Guide

Plan your path to financial independence with interactive FIRE projections, Social Security estimates, and multi-account withdrawal modeling.

Overview

The FIRE Retirement Calculator simulates your financial future from now through retirement and beyond. It finds your earliest safe FIRE age, projects portfolio balances across brokerage, Roth, and traditional accounts, and estimates your Social Security benefit — all in today’s dollars.

Every input uses a slider for quick exploration and supports click-to-edit for precise values — look for the dashed underline and “Click to type a value” tooltip on editable numbers. Changes auto-save locally and to your account if you’re logged in.

Key Metrics

The top of the calculator displays four key metrics that update in real time:

  • FIRE Number — the portfolio value needed to sustain your spending at your target retirement age, calculated from the safe withdrawal rate.
  • Earliest FIRE Age — the first age where a full year-by-year withdrawal simulation survives to your life expectancy without running out of money.
  • Depleted at Target Age — an independent simulation starting at your target retirement age, showing when (if ever) the portfolio runs dry.
  • Est. SS Benefit — your estimated monthly Social Security benefit at your chosen claiming age.

Your Situation

These inputs describe where you are today:

  • Current Age — your age today (20–60).
  • Life Expectancy — how long you plan for (70–105). Longer life expectancy lowers the safe withdrawal rate.
  • Years Worked So Far — used to estimate your Social Security earnings history.
  • Life-to-Date Avg Salary — your average salary across past working years, used for SS calculation.
  • Current Annual Income — your current salary, projected forward with raises for future SS earnings.
  • Avg Annual Raise — expected annual raise percentage applied to future income projections.

Account Inputs

The calculator models three account types, each with different tax treatment and withdrawal rules:

  • Brokerage (Taxable) — current balance and monthly contribution. Accessible at any age without penalty.
  • Roth IRA / Roth 401k — balance, monthly contribution, and total contributions basis. Contributions (basis) can be withdrawn penalty-free at any age; gains are penalty-free after 59½.
  • Traditional 401k / IRA — balance and monthly contribution. Withdrawals before 59½ incur penalties; fully accessible after.

All slider inputs use a logarithmic scale so you can precisely set both small and large values. Click any displayed value to type an exact number.

Withdrawal Order

The simulation uses a tax-aware withdrawal strategy:

  • Before 59½ — Brokerage first, then Roth contributions (basis only), then Traditional (with penalty).
  • After 59½ — Brokerage first, then Traditional, then Roth (gains last for maximum tax-free growth).

Retirement Settings

  • Monthly Spending in Retirement — your baseline monthly spending in today’s dollars.
  • Target Retire Age — the age you’d like to retire. The chart and “depleted” metric simulate from this age.

Spending Modifiers

Two optional toggles adjust spending over time to better reflect real-world patterns:

  • Retirement Smile — models the common pattern where retirees spend more in early retirement (travel, hobbies), less in their 70s and 80s. Set an early boost percentage (retire–70) and a late reduction (after 80), with a linear transition between 70–80.
  • Healthcare Escalator — adds an extra monthly healthcare cost starting at a specified age, reflecting increased medical expenses in later life.

Social Security

The calculator estimates your Social Security benefit using a simplified version of the SSA formula:

  • Past earnings are wage-indexed using your average salary and years worked.
  • Future earnings are projected using your current income and expected raises.
  • The top 35 years of earnings determine your AIME (Average Indexed Monthly Earnings).
  • PIA (Primary Insurance Amount) is calculated using the standard bend-point formula.
  • Claiming before 67 reduces the benefit; delaying past 67 increases it up to age 70.

The info box below the SS claiming age slider shows the full calculation breakdown.

Market Assumptions

  • Investment Return (Nominal) — expected annual return before inflation (default 7%).
  • Inflation Rate — expected annual inflation (default 3%). The real return used in calculations is (1 + return) / (1 + inflation) - 1.

Safe Withdrawal Rate

The calculator uses a dynamic safe withdrawal rate based on the length of your retirement:

  • 20 years or less: 4.5%
  • 25 years: 4.0%
  • 30 years: 3.8%
  • 35 years: 3.5%
  • 40 years: 3.3%
  • 45 years: 3.1%
  • 50+ years: 3.0%

The FIRE number is your adjusted annual spending at your target age divided by this rate.

The Chart

The stacked bar chart shows your projected portfolio balance from your target retirement age through life expectancy, broken down by account type (Brokerage, Roth, Traditional). Overlaid lines show:

  • FIRE number (red dashed) — the target portfolio value.
  • Monthly spending (orange dashed) — your spending at each age (scaled to fit the chart).
  • Target age dot (orange) — marks your target retirement age on the chart.
  • SS starts triangle (red-orange) — marks when Social Security benefits begin.

Hover over any bar to see exact values for that age.

Year-by-Year Detail

Click the detail button to open a table showing every year from retirement through life expectancy. Each row includes account balances, contributions, withdrawals, and estimated taxes so you can see exactly how your money moves over time.

Bridge Gap Warning

If your target retirement age is before 59½, the calculator checks whether you have enough in brokerage + Roth contributions to cover spending during the gap years before you can access retirement accounts penalty-free. A warning appears if your bridge funds fall short.

Saving Your Settings

Settings auto-save to your browser’s local storage after 1 second of inactivity. If you’re logged in, they also sync to your account so you can pick up where you left off on any device.

Tips

  • Look for the dashed underline on values — click any of them to type an exact number.
  • Try adjusting one variable at a time to see its impact on your earliest FIRE age.
  • Enable the Retirement Smile if you expect to travel more early in retirement and slow down later.
  • If retiring before 59½, make sure your brokerage account is large enough to bridge the gap.
  • Delaying Social Security to 70 can significantly reduce the portfolio needed, especially for longer retirements.