How the numbers are made
Methodology
Every figure in Promi comes from somewhere specific. This page says where, and what each one assumes.
Where the data comes from
Account balances, transactions and investment holdings come from your own institutions through Plaid, on a read-only connection. Promi cannot move money.
Market history comes from FRED, the Federal Reserve Bank of St. Louis data service. Long-run averages carry a coverage guard: a series that does not cover at least 90 percent of the period being averaged is not shown as an average for that period. Equity and NASDAQ figures are price indexes, so they exclude dividends, and that caveat travels with the number wherever it is displayed.
Budget starting points come from Bureau of Labor Statistics Consumer Expenditure Survey data for your income tier, scaled to your metro's cost of living. Peer comparisons come from the Federal Reserve Survey of Consumer Finances and the US Census Bureau.
How projections work
Projections run in today's dollars. Returns are real returns, expenses stay flat in real terms, and anything fixed in nominal terms (a pension without a cost of living adjustment, for instance) is deflated on the way in. That keeps a projected balance readable as money you understand today.
Real return is computed with the Fisher relation, dividing nominal by inflation rather than subtracting one from the other. The difference is small in a single year and compounds into a materially different answer over thirty.
Retirement outcomes run as a 1,000-path Monte Carlo simulation, reported as the share of paths where the portfolio lasts to age 95. Alongside it, a historical backtest replays your plan through actual market sequences, including the ones that went badly, because the order returns arrive in matters as much as their average.
Households with two people retiring at different times are modeled as such, with the earlier retiree's spending drawn and any claimed benefits flowing in while the other is still working.
How taxes are modeled
Tax on retirement withdrawals is derived rather than assumed. For each year, Promi computes the tax on your other income, then the tax on that income plus the withdrawal, and charges the difference against the withdrawal. Your working-years effective rate is not applied to retirement dollars.
Social Security is treated under IRC section 86, so the taxable share depends on combined income rather than every dollar being taxed as ordinary income. State treatment of benefits is applied only in the states that tax them.
Contributions are modeled by tax character. Pre-tax employee deferrals reduce taxable income, employer match counts toward the portfolio without reducing take-home pay, and Roth contributions do neither.
Tax figures use the 2025 federal bracket tables and standard deduction. Promi is not a tax preparer and these figures are estimates for planning, not filing.
What Promi does not do
Promi does not tell you what to do with your money. It will show you what the numbers say, how you compare to households in a similar position, and what a scenario looks like if you model it. It will not tell you which debt to pay first, where to move money, or what to buy.
That is a deliberate position rather than a missing feature. Promi is not a registered investment advisor, and an app that hands out personalized financial advice without being one is doing something it should not.
Promi also does not sell your data, take affiliate commissions on products it shows you, or run ads. The subscription is the whole business model, which is what makes the first paragraph possible.
Disclosures
Projections are estimates based on historical data and your inputs. Past performance does not guarantee future results. Promi is not a registered investment advisor and does not provide personalized financial advice.
Peer comparisons are drawn from publicly available data sources including the Federal Reserve Survey of Consumer Finances and the US Census Bureau.
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