How to enter your information correctly, what the numbers mean, and the assumptions the calculator makes behind the scenes. Jump to any topic below.
RetirFi needs no account and no login. Everything you enter saves automatically to your browser's local storage. Your data never leaves your device unless you choose to back it up.
Because your plan lives in the browser, clearing your cache or switching to a different device or browser will lose it. Use Save Plan in the header to email yourself a restore link, or copy a shareable link to reopen the same plan anywhere.
On your first visit, a short guided wizard collects the essentials so you get a result quickly. You can load a fully worked example any time with Load Sample (the Alex & Jordan household) to see how a complete plan looks, then Reset to start from blank.
↑ Back to topTwo inputs drive much of the projection: your retirement age and your monthly income goal (your target retirement spending). The spending goal is required. Without it, there's nothing for the simulation to fund. Enter what you'll need per month in today's dollars, and RetirFi inflates it forward for you.
RetirFi estimates your Social Security benefit from your income and years worked using the SSA's PIA formula. It's a reasonable approximation, but your real benefit depends on your full 35-year earnings record. For accuracy, look up your number at ssa.gov/myaccount and switch the card to Manual to enter it directly.
Your claim age (62 to 70) changes the benefit: claiming earlier means smaller checks, later means larger ones. The break-even between claiming at 62 and 70 is usually around age 80–82. On the Monte Carlo simulation itself, you have the option to pick any age between 62 and 70, and you can even compare the results of different ages with the "Compare a Scenario" run.
Turn on "Include spouse" to model a married couple. The plan then runs until the second death. When the first spouse dies, Social Security switches to the higher survivor benefit, household spending drops by a percentage you set, and the tax filing status changes to single.
↑ Back to topThis is where most mistakes happen, and where a few simple rules keep your projection accurate.
⚠ The most common mistake. Enter your loan information only in the Liabilities section. Don't also add them as expenses.
Enter every loan (mortgage, car, student debt) in the Liabilities section. RetirFi amortizes each one and subtracts the payment from your cash flow automatically, then stops the payment once the loan is paid off. If you also list that payment as an expense, it gets counted twice, and your free cash flow and projection will be wrong.
Your Expenses section should hold only living costs: groceries, utilities, insurance, travel, and so on. Property tax and homeowner's insurance belong in the mortgage's escrow field, not as separate expenses, unless of course you own your home free and clear.
Whatever is left of your take-home pay after living expenses, debt payments, and account contributions is your excess cash flow. By default the simulation treats it as spent. The Excess Cash Flow Allocation card lets you invest some or all of the surplus instead. You can split it by percentage or fixed dollars across your accounts, and it would be added on top of your contributions in every pre-retirement simulation year. I set the default to spend the surplus for two reasons. First, unexpected, one-time, or emergency expenses usually don't make it into the budget line items. Second, in my professional experience, most people spend excess cash flow if they've already built savings into the budget.
The surplus cash card lives in two places: on the Income & Expenses page below your expense list, and on the Dashboard behind ⚙ Configure allocation. They're the same setting, so a change in either place updates both.
Now here's where I contradict myself. If you entered your income and monthly spending in the setup wizard, the default is to direct 100% of your surplus to your first taxable account, falling back to your first cash account, then your first account of any kind. Only if you entered no assets at all does it create a new $0 "Brokerage" account to receive the surplus. You can adjust the split any time. The reason for the discrepancy is more psychological. The setup wizard is for a quick setup, and users enter less information this route, with more rounding and assumptions such as income − expenses = savings. So here I default to savings and not spent.
Add the account itself first. On the Assets page, create a retirement account (401(k), IRA, Roth, or similar) and enter its current balance. The balance is what you have today; contributions are what you add each year, and RetirFi treats them separately.
You have two ways to tell RetirFi about ongoing contributions. The simple way is to type a flat dollar amount into the account's Annual Contribution field, for example $12,000 per year. The better way is to link the account to your paycheck. On the Income page, open your salary and add a contribution link to the account, either as a percentage of that income or as a fixed amount. A linked contribution rises with your raises and stops automatically when that income ends at retirement, which is exactly how a real 401(k) behaves.
Use one method or the other, not both. Once an income is linked to an account, the link takes over. The account's Annual Contribution field becomes read-only and displays the amount coming from the linked income, and the simulation uses the linked amount instead of the flat number, so nothing gets double-counted. To go back to a flat contribution, remove the link on the Income page.
If your employer matches, turn on the employer-match option and set two numbers:
The match equals your contribution, capped at salary × match-up-to %, multiplied by the match %. So a 50% match up to 6% of a $100,000 salary (with you contributing at least $6,000) adds $3,000 per year on top of your own contribution in every simulation year. The match settings appear on both the account and the linked income; they're one setting, so a change in either place updates both.
However you enter contributions, RetirFi caps them at the IRS annual limit for the account type (401(k) vs. IRA), including age-based catch-up amounts, so an oversized entry can't inflate your savings. Note that 529 college-savings accounts count toward your net worth but are excluded from retirement drawdown, since they're earmarked for education.
Add your home as a real-estate asset and link it to its mortgage in the Liabilities section. Your net worth then correctly nets the home value against the loan balance, and the home isn't treated as a liquid account. Only cash, brokerage, and retirement accounts are spent down in retirement, and real estate stays on the balance sheet.
↑ Back to topThe bar at the top of the Monte Carlo tab sets your assumptions: dollar mode, retirement spending, lifespan(s), inflation, and number of simulations. More simulations give a more precise model. 200 is a good balance, and 1,000 is the most precise. Press Run to simulate.
It's the share of simulated futures in which your portfolio doesn't run to zero before the end of your plan. An 85% result means your money lasted in 85 of every 100 simulated market histories. Financial planners commonly target 80–90%. Higher isn't always better, since a 99% result often means you're underspending and will likely leave a large amount unspent. Additionally, if worse economic conditions persist over the long term (the bottom 20% of scenarios), you would adjust your spending and savings habits accordingly, bringing your percentage back up. A financial plan is dynamic and ever changing, not static. In real life, we make adjustments.
Nominal dollars are the raw future numbers your statement will show. Real dollars are inflation-adjusted to today's purchasing power. At 2.5% inflation, $1 million in 30 years buys roughly what $480,000 buys today. Toggle between the two in the control bar.
These are my favorite features. Compare a scenario lets you build a "Scenario B" (retire earlier, claim Social Security later, or spend differently) and overlays it on your current plan so you can see the difference side by side. Plan Insights works backward from a target success rate to find your maximum safe spending, your earliest retirement age, and some suggested changes that move your odds the most.
↑ Back to topOnce you've run a simulation, the Year by Year tab in the calculator's sidebar replays it as a timeline you can read line by line.
The tab reads your latest Monte Carlo run, so run a simulation first; it stays empty until you do. The chart stacks your account balances over the whole plan, colored by tax type, so you can watch taxable money spend down first while Roth is preserved for last, exactly the drawdown order the engine follows.
The table below flips the usual layout. Accounts are rows and years are columns, stepping in five-year jumps. Milestone years (retirement, each planned event, the first death, plan end) are always included and tagged so the important columns never fall between steps. Use the ‹ › arrows or the dots to page through five columns at a time.
Click the Portfolio, Income, or Spending row to expand it. Portfolio breaks out each account, Income splits into your income sources plus Social Security and RMDs, and Spending itemizes your expenses and debt payments. A Taxes row runs along the bottom.
The Scenario picker chooses which simulated future you're viewing, from Bull (90th percentile) down to Bear (10th). The default, Median (50th), is the middle outcome, with half the simulated futures doing better and half worse. Switch to Bear to see the same plan under persistently poor markets; that view is the stress test that matters most, because it shows whether the plan survives the futures that drag your success rate down.
The Dollars toggle works like the one on the Monte Carlo tab. Nominal shows the raw future dollars a statement would show; Today's $ discounts every figure by your inflation assumption so amounts stay comparable to your current budget.
Every column is one representative simulated path from your latest run, not an average of all runs. Retirement-year figures (Social Security, RMDs, taxes, spending) come straight from that simulation. For working years the simulation tracks only balances, so the table rebuilds your earned income from your Income entries, applying their growth rates and start, end, and stop-at-retirement settings, and estimates tax from your effective take-home rate.
Expense line items are prorated. The engine models one spending total per year, and the table splits it across your expense entries by their share of the budget. And because each run draws fresh random returns, the numbers shift slightly every time you re-run the simulation. That's normal for Monte Carlo, and the more simulations you run, the steadier the percentile paths get.
↑ Back to topThe IRA Calculators tab holds two what-if tools, a Contribution comparison (Roth vs. Traditional) and a multi-year Roth Conversion planner. Both are read-only; nothing you do there changes your plan.
Every input auto-fills from your plan, and the small badge next to each field says where the value came from ("your marginal rate", "retire at 65", "Monte Carlo median"). Type over any field to test a what-if; the badge flips to overridden · reset ↺, and clicking it relinks the field to your plan value.
The retirement tax rate is the one field that improves with a Monte Carlo run. With a run available, it uses the effective federal rate along your median simulated path, which is total retirement tax divided by the gross income that funded your retirement spending. Without a run, it falls back to an estimate from your spending goal, Social Security, and the tax brackets.
The tool answers one question. For the same yearly dollars into each account, which leaves more after-tax spending money at retirement? Five inputs drive it, and each defaults from your plan. They are your annual contribution, years until retirement, growth rate, tax rate today, and tax rate in retirement.
The model puts the same dollars into each account every year, so both grow to an identical pre-tax balance. Roth withdrawals come out tax-free. The Traditional balance is taxed at your retirement rate on the way out, but the deductible contribution also saves you tax today (contribution × current rate). The checkbox decides what happens to that saving. Invest some or all of it in a taxable side account (gains taxed at a 15% capital-gains rate) and it counts toward the Traditional column; spend it and it's gone.
The bottom row, Total after-tax value, is the verdict. The usual pattern holds. A higher tax rate today than in retirement favors Traditional, the reverse favors Roth, and whether you actually invest the tax savings often decides close cases.
A Roth conversion moves money out of a Traditional (pre-tax) account into Roth, paying ordinary income tax now to avoid it later. The planner needs a Monte Carlo run first, because it reads your median path year by year (income, tax bracket, pre-tax balance) to find the years where converting is cheapest.
The banner highlights your low-income window, the years after you retire but before RMDs begin, when your taxable income and bracket dip. Each eligible year appears as a chip; click chips to add or remove years, and the "best" tags mark the years with the most bracket room. Pick an auto-fill target and every selected year converts just enough to reach the top of that bracket after its other income (earned income, RMDs, and the taxable share of Social Security, computed with the IRS provisional-income tiers). You can also type an exact amount into any row of the schedule; rows flagged in red exceed the pre-tax balance the projection says is still available that year.
Leave pay the conversion tax from outside cash checked to let the full conversion keep compounding tax-free. Uncheck it and the tax comes out of the converted amount itself, so less lands in the Roth.
The payoff table compares two futures at your plan's end. Converted dollars grow tax-free with no RMDs. Dollars left in Traditional face RMDs from age 73 or 75, each forced withdrawal taxed at that year's bracket on top of your simulated income and the after-tax remainder reinvested in a taxable account; whatever is still inside at the end is taxed at your blended retirement rate. If you'd have paid the conversion tax from outside cash, the leave-in column keeps and invests that cash too, so both paths compare equal dollars. A positive benefit means the schedule pays for itself; a negative one means you're converting too much or filling too high a bracket.
Both tools use 2024 federal brackets and standard deductions for your filing status, a single blended 15% capital-gains rate on taxable side accounts, and SECURE 2.0 RMD rules. They ignore state income tax, IRMAA Medicare surcharges, ACA premium subsidies, the Roth five-year rule, IRA deduction phase-outs, and the step-up in basis at death. Treat the output as an educational estimate, not tax advice, and talk to a professional before an actual conversion.
↑ Back to topInstead of assuming one fixed return, RetirFi runs up to 1,000 simulations of future economic conditions with randomized year-to-year market shocks, capturing the sequence-of-returns risk that fixed-rate calculators miss. For the full explanation, see Monte Carlo simulation, explained.
In retirement, accounts are spent down tax-efficiently in this order: Taxable → Cash → Traditional → Roth. This preserves tax-advantaged growth for as long as possible. Pre-tax (traditional) contributions also reduce your taxable income while you're still working.
Required Minimum Distributions from traditional accounts begin at age 73 or 75 (per SECURE 2.0, based on your birth year) and are modeled automatically, including their tax impact. Take-home pay is derived from federal and FICA taxes for your filing status.
RetirFi is an educational tool, not financial advice.
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