Best Free Retirement Calculators in 2026: Which Fits Your Question?
Start with what you need to learn: how much spending your portfolio might support, how it would have handled difficult historical periods, or what happens when you change the assumptions. These four calculators take different approaches. None can tell you where markets will go.
Portfolio Lab publishes this comparison and builds one of the tools below. The comparison focuses on each tool's method and scope, with links to the providers' own explanations.
Try the free retirement calculatorNo signup needed. US dollars, stock/bond/cash allocations, 20 to 40 years.
Compare the methods
| Tool | Method | Useful for |
|---|---|---|
| Portfolio Lab | Monte Carlo using published long-term return assumptions. | A quick stock, bond and cash spending scenario in US dollars over 20 to 40 years. |
| cFIREsim | Historical retirement periods; configurable spending, income and allocation. | Exploring how a plan fares across different historical starting years. |
| FI Calc | Historical backtesting with a choice of withdrawal strategies. | Comparing portfolio survival with changes in the spending a strategy permits. |
| FIRECalc | Historical periods by default; optional constant growth or random returns. | Testing spending, income, fees and retirement timing under different settings. |
Portfolio Lab: a simple scenario starting point
The free public calculator runs 1,000 model-generated return paths. Enter a starting portfolio, monthly spending and a stock/bond/cash allocation, then choose 20, 25, 30, 35 or 40 years. It reports the share of simulated paths that survive and a range of ending values. All amounts are in US dollars.
Its return model uses lognormal returns with an adjustment for skewness and kurtosis. The calculator's methodology explains its return assumptions, fees, inflation and withdrawals. These are modelling choices, not evidence that this method forecasts better than the alternatives. The simple tool does not calculate personal taxes or provide a detailed pension and Social Security plan.
The withdrawal-rate calculator and signed-in workstation are separate tools. Their asset choices and analysis options are not all available in this public calculator.
cFIREsim: historical retirement sequences
cFIREsim tests a plan across historical retirement periods. Its controls include stocks, bonds, gold and cash, spending rules, income adjustments and changes in allocation. This makes it useful for examining how a plan responds to different starting years and spending choices.
Historical replay retains the returns observed in those periods; it does not require assuming they follow a normal distribution. The available history still limits the stresses it can show. Read the cFIREsim method and input guide.
FI Calc: withdrawal strategies and spending tradeoffs
FI Calc evaluates retirement plans using historical data and offers a range of withdrawal strategies. Alongside portfolio survival, it shows outcomes for available spending. Income and extra withdrawals can be included. This helps when you want to compare a steady spending rule with one that changes as the portfolio changes.
Its documentation says to include taxes in your planned withdrawals because it does not automatically estimate them. See the FI Calc withdrawal-strategy guide.
FIRECalc: historical tests with optional return models
FIRECalc uses historical retirement periods by default. It also offers constant-growth and random-return alternatives, with inputs for the random model's mean return and standard deviation. Its controls cover spending, other income, fees, retirement timing and portfolio changes.
Check which return option you selected before comparing its result with another calculator: a historical run and a random-return run answer different questions. The settings and explanations are on the FIRECalc calculator.
Make the comparison useful for your plan
- Keep the inputs comparable. Use the same starting portfolio, spending, allocation and retirement length. Check whether amounts are nominal or inflation-adjusted.
- Check the assumptions. Return data, inflation, fees, tax treatment and withdrawal timing can explain differences in results.
- Inspect difficult outcomes. Look at when money runs out or spending falls, as well as the headline survival percentage.
- Change one decision at a time. Compare a lower spending amount or longer horizon, then use a different method as a cross-check. Agreement between calculators is not a guarantee.
Frequently asked questions
What is the best free retirement calculator?
Choose by the question you want to test. Portfolio Lab's simple calculator explores model-generated return scenarios. cFIREsim and FI Calc test plans against historical periods and offer spending choices. FIRECalc uses historical periods by default and also offers constant-growth and random-return options. No calculator can establish that a retirement plan is certain to succeed.
Is Monte Carlo simulation better than historical backtesting?
They answer different questions. Historical backtesting shows what a plan would have done during the periods in its dataset. Monte Carlo generates paths from a specified model and assumptions. Both can reveal weaknesses, and both can miss risks. A model with more paths or more parameters is not automatically more accurate.
Do I need an account to use Portfolio Lab's retirement calculator?
No. You can run the free public calculator without signing up. It models a stock, bond and cash allocation in US dollars over 20, 25, 30, 35 or 40 years. The separate signed-in workstation has a broader set of portfolio tools; its features should not be confused with this simple calculator.
What does a retirement survival rate mean?
It is the share of the tested paths in which the portfolio meets the calculator's survival definition. A historical rate describes the periods tested; a Monte Carlo rate describes the simulated paths under that model. Neither is a guarantee or a directly observed probability of your own future retirement succeeding. Review spending, taxes, fees, inflation and the length of retirement alongside the percentage.
Try a spending scenario
Run the free calculator, then change one input and compare the results.
Open the retirement calculatorRelated
Educational tools cannot replace a plan that accounts for your own circumstances. Product features can change; follow the linked providers for their current options. Full disclaimer.