Best FIRE Calculator Comparison 2026: 11 Tools Reviewed
An honest review, with a feature matrix
The Honest Truth
There are dozens of FIRE calculators. Some cost $100+/year. Some have features we don't. Here's an honest comparison so you can pick the right tool for your needs.
We built firenum.com because we wanted something specific: a fast, private, multi-currency set of calculators that works offline. That's our niche. Other tools excel at different things.
Research from Vanguard confirms what we've seen firsthand: "Investors who use financial planning tools report 25% higher confidence in their retirement readiness." The right calculator isn't just about features. It's about building confidence in your plan.
If tax optimization or account aggregation matter more to you than privacy and multi-currency support, there are better options. We'll tell you which ones. But for Monte Carlo, historical backtesting, and stress testing, firenum now does all of that, free, with no account required.
Quick Comparison
| Feature | firenum | Engaging Data | FI Calc | ProjectionLab | Boldin |
|---|---|---|---|---|---|
| Price | Free | Free | Free | $109/yr | $144/yr |
| Account Required | ✗ | ✗ | ✗ | ✓ | ✓ |
| Multi-Currency | ✓ 9 currencies | ✗ | ✗ | ✗ | ✗ |
| Progress Tracking | ✓ | ✗ | ✗ | ✓ | ✓ |
| Stress Test Scenarios | ✓ 5 scenarios | ✗ | ✓ via backtesting | ✓ | ✓ |
| One-Time Events | ✓ | ✗ | ✗ | ✓ | ✓ |
| Monte Carlo | ✓ 100-5,000 runs | ✓ | ✗ | ✓ | ✓ |
| Historical Backtesting | ✓ 1871-present | ✗ | ✓ 100+ years | ✓ | ✗ |
| Cash Flow Visualization | ✓ Sankey diagram | ✗ | ✗ | ✓ | ✗ |
| Withdrawal Strategies | ✓ 3 + 59.5 rule | ✓ | ✓ | ✓ | ✓ |
| Portfolio Survival Heatmap | ✓ | ✗ | ✗ | ✗ | ✗ |
| Tax Optimization | ✗ | ✗ | ✗ | ✓ | ✓ |
| Mobile-First | ✓ | ~ | ✓ | ✓ | ~ |
| Works Offline | ✓ | ✗ | ✗ | ✗ | ✗ |
| 100% Private | ✓ localStorage only | ✓ | ✓ | ✗ | ✗ |
What firenum Does Best
Monte Carlo Simulation
100-5,000 runs with drift-corrected lognormal returns, configurable volatility, and customizable parameters. Get success probability and percentile bands: the same analysis ProjectionLab charges $109/year for.
Historical Backtesting
Every starting period from 1871-present using Shiller S&P 500 data. One run per January the data covers (105 historical starting years for a 50-year projection, 125 for a 30-year one), with worst/best case outcomes and a portfolio survival heatmap. See how your plan would have survived every market regime in history.
Cash Flow Visualization
Sankey diagram showing money flow for any projection year: income sources, expense categories, savings, and withdrawals. Toggle between accumulation and retirement views to see exactly where every dollar goes.
Stress Test Scenarios
5 built-in scenarios: market crash (timing, severity, recovery), lower returns, income loss, expense spike, and high inflation (with duration). See how your plan holds up when things go wrong.
Multi-Currency Support
9 currencies: USD, EUR, GBP, CAD, AUD, CHF, JPY, INR, NZD. Most FIRE calculators are US-only. If you live outside the US or hold assets in multiple currencies, this matters.
One-Time Events
Model windfalls, inheritance, home sales, or large purchases at specific future dates. See exactly how a $50k bonus in 3 years or a $200k home sale at retirement changes your trajectory.
100% Private
Your data never leaves your device. No account required, no cloud sync, no analytics on your financial data. Everything stays in localStorage. Works offline too.
Plus: 8 calculators in one place, mobile-first design, dark/light themes, no ads, sub-second load times.
Where Competitors Excel
Let's be honest about our limitations. These tools do things we don't:
Tax Optimization
Boldin and Pralana model Roth conversions, tax-loss harvesting, and Social Security timing. If you're optimizing for US taxes, these tools are significantly more sophisticated.
Account Aggregation
Empower (formerly Personal Capital) pulls balances from all your accounts automatically. Convenient if you have accounts spread across many institutions.
Social Security Optimization
Boldin models optimal Social Security claiming strategies: when to start, spousal benefits, and how claiming age affects your total lifetime payout. Critical for US retirees leaving money on the table.
Detailed Competitor Reviews
Free Tools
Engaging Data
FreeBest for: Monte Carlo simulations
Strengths
- Detailed Monte Carlo analysis
- Multiple withdrawal strategies
- Social Security integration
Limitations
- US-focused
- Single currency
- No progress tracking
FI Calc
FreeBest for: Historical backtesting
Strengths
- 100+ years of historical data
- Multiple portfolio strategies
- Variable spending models
Limitations
- US market data only
- Single currency
- No ongoing tracking
cFIREsim
FreeBest for: Community-validated simulations
Strengths
- Long-standing community tool
- Flexible spending rules
- Historical analysis
Limitations
- Dated interface
- US-only
- No mobile optimization
WalletBurst
FreeBest for: Clean visualizations
Strengths
- Beautiful charts
- FIRE timeline calculator
- Savings rate focus
Limitations
- Fewer calculator types
- US-focused
- Limited customization
InvestToFire
FreeBest for: Pension and VA income holders
Strengths
- Subtracts pension/VA/side income from your FIRE number
- Inflation-correct Coast FIRE math
- Year-by-year US withdrawal tax planner
Limitations
- USD only
- Inputs reset on reload
- Fixed-return projections (no Monte Carlo)
We tested InvestToFire's three strongest calculators hands-on and verified the math to the dollar. Full write-up: InvestToFire review.
Paid Tools
ProjectionLab
$109/yearBest for: Best overall paid option
Strengths
- Comprehensive scenario planning
- Monte Carlo + historical
- Tax-aware projections
- Beautiful interface
Limitations
- Subscription cost
- Learning curve
- Account required
Boldin (NewRetirement)
$144/year (Plus)Best for: Tax optimization
Strengths
- Detailed tax modeling
- Social Security optimization
- Roth conversion planning
Limitations
- Higher cost
- US tax-focused
- Complex for simple needs
Pralana
$119 one-timeBest for: Complex scenarios
Strengths
- Excel-based flexibility
- Detailed tax modeling
- One-time payment
Limitations
- Spreadsheet required
- Steep learning curve
- Windows-focused
Empower (Personal Capital)
Free tools (0.89% AUM for advisory)Best for: Account aggregation
Strengths
- Free account aggregation
- Fee analyzer
- Investment checkup
Limitations
- Pushes advisory services
- Privacy concerns
- Free tier limited
Spreadsheets
Sometimes a spreadsheet is the right tool. These are the best free FIRE spreadsheets:
Mad Fientist FI Spreadsheet
The gold standard free FIRE spreadsheet. Comprehensive tracking with clear instructions.
Download →Big ERN SWR Toolbox
Deep safe withdrawal rate analysis. Best for understanding sequence-of-returns risk.
Download →How to Choose
- Privacy is paramount? → firenum (100% local storage)
- Live outside the US? → firenum (multi-currency)
- Want Monte Carlo + backtesting + privacy? → firenum (all free, no account)
- Have a pension or VA income? → InvestToFire (subtracts it from your FIRE number)
- Need tax optimization? → Boldin or Pralana
- Want automatic account aggregation? → Empower
- Need Social Security optimization? → Boldin
- Best overall paid option? → ProjectionLab ($109/yr)
- Prefer spreadsheets? → Mad Fientist FI Spreadsheet
- Want fast, simple, and free? → firenum
Frequently Asked Questions
firenum runs 100-5,000 Monte Carlo simulations using drift-corrected lognormal returns with configurable volatility. You get success probability, percentile bands, and can combine it with historical backtesting from 1871-present. ProjectionLab charges $109/year for similar capabilities. The main differences: paid tools like Boldin add tax-aware modeling, and ProjectionLab offers Roth conversion scenarios. For pure simulation quality, firenum matches or exceeds most paid options.
Yes. No premium tier, no account required. Everything is included. The site runs on minimal infrastructure costs. We may add affiliate links to recommended books or services in the future, but the calculators will always be ad-free with no paywall.
All FIRE calculators are projections based on assumptions about future returns. None can predict the future. The value is in understanding the math and relationships between variables (savings rate, expenses, returns) rather than getting an exact retirement date. Use any calculator as a planning tool, not a guarantee.
Yes, especially for major decisions. Different calculators use different assumptions and may highlight different aspects of your plan. If multiple calculators give similar answers, that's a good sign. If they differ wildly, investigate why.
Paid calculators typically offer advanced features like account aggregation, tax optimization, Social Security optimization, and Roth conversion planning. Some features that used to be paid-only (like Monte Carlo and historical backtesting) are now available for free in tools like firenum. Whether the cost is worth it depends on your complexity and how much you'll use the tax and account integration features.
Absolutely. Account aggregation is a convenience feature, not an accuracy feature. You can manually input your balances into any calculator. The math is the same whether your data is pulled automatically or entered by hand. Manual entry also means your financial data never leaves your device.
Ready to run the numbers?