Not all FIRE calculators are created equal. Some model taxes. Some model the bridge years. Some do neither. Here is an honest, feature-by-feature comparison of the five most popular tools.
Last updated February 2026 · 2025 IRS tax data
| Feature | BridgeToFI | cFIREsim | FICalc | FIRECalc | Boldin |
|---|---|---|---|---|---|
| Price | Free | Free | Free | Free | $120-$480/yr |
| Account Required | No | No | No | No | Yes |
| Data Privacy | Client-side onlyZero data sent to servers | Client-side | Client-side | Client-side | Server-stored |
| Last Updated | Feb 2026 | Nov 2024 | 2023 | ~2020 | 2026 |
| Simulation Engines | |||||
| Historical Backtesting | YesNamed crash sequences (2008, dot-com, stagflation) | YesCore feature, data since 1871 | YesData since 1871 | YesData since 1871 | No |
| Monte Carlo Simulation | 1,000+ trialsPercentile bands, inflation-adjusted view | No | No | No | YesMonte Carlo only |
| Deterministic Projection | Year-by-yearFull data table + interactive charts | No | No | No | Yes |
| Tax Modeling | |||||
| Federal Income Tax | Progressive brackets7 brackets, 2025 IRS constants | None | None | None | YesFederal + state |
| Capital Gains Tax | Stacked 0/15/20%LTCG stacked on ordinary income | None | None | None | Simplified |
| NIIT (3.8% surtax) | Yes | No | No | No | Limited |
| Social Security Taxation | Provisional income50%/85% thresholds modeled | No | No | No | Yes |
| IRMAA Medicare Surcharges | 6 brackets + 2yr lookback | No | No | No | Basic |
| Early Retirement Features | |||||
| Bridge Strategy (pre-59.5) | P1/P2/P3 systemPriority-based withdrawal sequencing | No | No | No | No |
| Roth Conversion Ladder | 5-year lot trackingPer-conversion seasoning queue | No | No | No | Basic |
| Rule of 55 | Yes | No | No | No | No |
| SEPP/72(t) | YesCalculates payment amounts | No | No | No | No |
| RMD Modeling | SECURE Act 2.0Ages 73/75 by birth year | No | No | No | Yes |
| Spending Guardrails | Guyton-Klinger style | Limited | Multiple strategies | No | Basic |
| Other Features | |||||
| Partner/Spouse Modeling | FullSurvivor SS, joint accounts, separate ages | Basic SS only | No | Basic SS | Yes |
| Social Security Optimization | Breakeven analysisSpousal + survivor benefits | Input only | No | Input only | Yes |
| Healthcare Costs | Separate inflation ratePre-Medicare + IRMAA modeling | No | No | No | Yes |
| Multiple Account Types | 401k, IRA, Roth, HSA, BrokerageEach with unique tax + access rules | Single portfolio | Single portfolio | Single portfolio | Multiple accounts |
| International Support | 6 countriesUS, UK, CA, AU, EU, India | US only | US only | US only | US only |
| Advisor Portal | Full portalWhite-label, clients, MFA, compliance | No | No | No | Advisor version |
| Mobile Friendly | Responsive + PWA | Basic | Responsive | Desktop only | Responsive + App |
| Account Linking | No (by design)Privacy-first: manual entry only | No | No | No | YesPlaid integration |
The only free calculator that models the bridge problem, progressive taxes, Roth conversion ladders with 5-year lot tracking, IRMAA surcharges, and three simulation engines. Built for people retiring before 59.5. No signup, no data collection. The only tool with 6-country support and an advisor portal.
Historical backtesting with market data since 1871. Good for quick "would my portfolio have survived?" checks. Treats your portfolio as one lump sum with no tax modeling or account types. Data last updated November 2024. Best for: simple historical survival analysis.
Clean interface with strong withdrawal strategy options: constant dollar, percent of portfolio, guardrails, CAPE-based, and more. Historical data only. No tax calculations, account types, or healthcare modeling. Best for: comparing how different withdrawal strategies perform historically.
The original FIRE calculator, online since 2000. Includes optimization tools for finding ideal withdrawal rates and asset allocations. Dated interface, not mobile-friendly. No tax modeling. Best for: withdrawal rate and allocation optimization.
Most comprehensive paid option with Plaid account linking, federal and state taxes, and RMD modeling. Monte Carlo only, no historical backtesting. Requires account creation. $120-$480/year. No bridge strategy or SEPP/72(t). Best for: traditional retirees who want account aggregation.
For anyone retiring before 60, start with BridgeToFI. It is the only tool that models the bridge years, tax brackets, and early access strategies together. Then cross-check with cFIREsim for historical validation. If you want account linking and are willing to pay, add Boldin. Using multiple tools builds confidence in your plan.
If you are retiring before 59.5, the most important question is: "How do I pay for the years between leaving work and when my 401k/IRA becomes penalty-free?" This is the bridge problem, and most calculators completely ignore it.
cFIREsim, FICalc, and FIRECalc all treat your portfolio as a single number. They do not distinguish between a brokerage account you can access tomorrow and a 401k that carries a 10% penalty before 59.5. That distinction determines whether a plan actually works or quietly fails.
BridgeToFI's P1/P2/P3 system separates accessible accounts (brokerage, cash) from partially accessible accounts (Roth contributions, HSA) from locked accounts (401k, Traditional IRA). It simulates the optimal drawdown order year by year, calculating the tax cost of each withdrawal source at each step.
A person with $1.5 million split between brokerage and 401k has a fundamentally different early retirement picture than someone with $1.5 million entirely in a 401k. The first person might retire comfortably at 45. The second person might face a funding gap. Only BridgeToFI models this correctly, which is why it was built.
Taxes are often the largest controllable expense in retirement. Early retirees face a unique opportunity: the years between leaving work and claiming Social Security or starting RMDs create a low-income window where strategic Roth conversions, capital gains harvesting, and bracket optimization can save tens of thousands of dollars over a lifetime.
A single filer can convert $48,475 of Traditional IRA funds to Roth each year and stay in the 12% federal bracket (2025 constants, above the $15,750 standard deduction). Meanwhile, long-term capital gains on brokerage withdrawals may fall entirely in the 0% bracket if total income stays below $48,350. These are massive tax savings that a calculator without tax modeling simply cannot identify.
BridgeToFI calculates progressive federal brackets, stacked LTCG rates, NIIT 3.8% surtax, Social Security taxation (provisional income method), and IRMAA Medicare surcharges with the 2-year lookback rule. Each interacts with the others: a Roth conversion that fills the 12% bracket might also push MAGI into a higher IRMAA tier two years later. Getting this right requires modeling all of the pieces together, which is exactly what BridgeToFI does.
For historical backtesting, cFIREsim and FICalc are well-validated against the Shiller dataset. For real-world planning that includes taxes, account types, and withdrawal sequencing, BridgeToFI provides a more complete picture because it models the factors that determine how much money you actually keep after taxes and penalties.
Absolutely. Different tools use different methodologies, and cross-checking builds confidence. BridgeToFI covers three approaches in one tool (deterministic, Monte Carlo, historical stress test), but verifying against cFIREsim's historical data or Boldin's account-linked projections adds another layer of validation.
The personal calculator is completely free with no limitations, no signup, no email, and no paywall. The business model is the advisor portal: financial professionals pay $99/month (Pro tier) to manage clients with white-label branding, compliance features, and branded reports. Individuals never need to pay anything.
By design. BridgeToFI's privacy architecture means your financial data never leaves your browser. No server-side storage means no breach risk and no third-party data sharing. You enter account balances manually, and all calculations run locally. This is a deliberate trade-off: slightly more setup effort in exchange for complete data privacy.
If you are retiring at 65 with access to Social Security, Medicare, and penalty-free retirement accounts, any of these calculators will work. Boldin's account linking may save you data-entry time. BridgeToFI still adds value through its tax modeling, IRMAA projections, and RMD calculations, but the bridge strategy features are less relevant when you do not have bridge years to fund.
No signup. No email. No data collection. Three simulation engines. Full tax modeling. The most comprehensive free early retirement calculator available.
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