Roth IRA growth calculator
Project Roth IRA balance at retirement with monthly contributions, expected return, and inflation adjustment. Includes the 2026 contribution cap check and an honest sustainable-withdrawal estimate.
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Project your balance
Total contributed over 35 years: $277,500. Growth: $1,027,318. At a 4% sustainable withdrawal rate, that supports roughly $4,349/month nominal ($1,833/month in today\'s dollars).
How the calculator computes the projection
Starting balance plus monthly contribution, compounded at the stated annual return divided by 12 (monthly compounding). Contribution is added at the start of each month, before that month\'s growth — matching how most US brokerages actually credit recurring transfers. The annualization of the monthly figure is shown next to the input so you can confirm at a glance whether you are inside the 2026 IRS contribution caps ($7,500 for under-50, $8,600 with the catch-up for 50+). If you are above the cap, the widget flags it; the projection still computes the math, but you would not be able to legally execute it inside a Roth IRA.
The inflation adjustment is a simple geometric discount: nominal projected balance divided by (1 + inflation rate)^years. This is the simplest defensible adjustment and it materially changes the felt size of the future balance. Without the adjustment, a $1.5 million projection feels like generational wealth; with a 2.5% inflation adjustment over 35 years, it deflates to roughly $630,000 in today\'s purchasing power. Both numbers are useful, depending on which mental model you are using.
The structural value of Roth treatment
Roth IRAs are funded with post-tax dollars: you pay income tax on the money the year you earn it, and then contribute. From that point on, the money grows tax-free, and qualified withdrawals after age 59½ are entirely tax-free at the federal level. There is no Required Minimum Distribution during the original owner\'s lifetime, which means you can let the Roth balance compound longer than a Traditional IRA or 401(k). For heirs, inherited Roths have a 10-year payout rule but the distributions remain tax-free.
The strategic implication is large for long-horizon savers. A 30-year-old who contributes $7,500/year to a Roth IRA for 35 years has put in $262,500 of post-tax money. At a 7% nominal return, the balance at age 65 is approximately $1.13 million — all tax-free at withdrawal. Compare that to the same money in a taxable account at the same returns, where capital gains, dividends, and eventual withdrawals would erode 20–30% of the terminal value to taxes. The Roth structure is, in dollar terms, the most valuable retirement tax-advantaged vehicle available to a US middle-income earner.
The Roth-vs-Traditional question, briefly
The conventional rule of thumb — "Roth when young, Traditional when old" — is right roughly half the time. The bracket-aware version: contribute to Roth when your current marginal tax bracket is at or below your expected retirement marginal tax bracket; contribute to Traditional when your current bracket is higher. A 28-year-old in the 12% bracket should overwhelmingly favor Roth (the tax cost now is low, and future bracket is almost certainly higher). A 52-year- old in the 32% bracket planning to retire in California at a 22% effective rate should mostly favor Traditional (the tax deduction now is more valuable than the future tax-free withdrawal).
Most savers end up with both, which is the right outcome — the optionality of drawing from either Roth or Traditional in retirement, based on the year\'s tax situation, is genuinely valuable. The tax-advantaged hierarchy guide in the investing section walks through the worked examples at typical brackets, including Social Security taxation thresholds, Medicare IRMAA brackets, and state tax differences between accumulation and retirement.
What the calculator deliberately does not model
Tax-bracket changes. The calculator assumes Roth-style treatment, which is bracket-agnostic in retirement. If you are projecting a Traditional IRA or pre-tax 401(k), the terminal balance is taxable on withdrawal, which means the effective balance you can spend is lower than the nominal projection by approximately your retirement marginal rate. For Traditional projections, mentally multiply the nominal balance by (1 − expected retirement marginal rate) to get a Roth-equivalent figure.
Variable returns. The calculator uses a constant annual return. Actual market returns are sequence-dependent: a bad first decade with a good second decade produces a different terminal balance than a good first decade with a bad second decade, even at the same arithmetic average return. Sequence-of-returns risk matters more for retirees drawing down a portfolio than for accumulators adding to it, but at the very end of accumulation it starts to matter. A conservative practice is to project at slightly below the long-run historical return to allow for sequence risk and elevated current valuations.
Other accounts. The Roth IRA is one piece of a typical US retirement portfolio. Most readers contributing to a Roth IRA are also funding a 401(k), possibly an HSA, possibly a taxable brokerage, possibly a 529 for kids. The full picture requires aggregating across accounts, which is what the 401(k) optimizer and retirement gap analyzer in the investing section are designed to do. This calculator handles the Roth IRA slice cleanly; the full retirement plan needs more inputs.
The most useful application
Where this calculator earns its keep is showing the long-run consequence of contributing or not contributing the cap. The math is stark: the difference between $0/month and $625/month ($7,500/year) into a Roth IRA over 35 years at 7% return is roughly $1.13 million in retirement assets. That is not a tactical decision — it is structural. The single highest-leverage personal finance lever for most US workers, after capturing the full 401(k) match, is consistently maxing the Roth IRA over their working career. Watching the calculator project seven figures of tax-free retirement wealth from a contribution that feels modest each month is the clearest argument for the discipline.
Frequently asked
Why does the calculator flag contribution amounts above $7,500 a year?
Because $7,500 is the 2026 IRS contribution cap for Roth IRAs for individuals under 50, and $8,600 is the catch-up cap for those 50 and over (an extra $1,100). The cap is per person, aggregate across Roth IRA and Traditional IRA contributions in the same tax year. The calculator surfaces the warning if your monthly figure annualizes above the relevant cap, because the projection assumes the contribution actually gets into the account — which the IRS will not allow above the cap. Excess contributions face a 6% per-year penalty until corrected.
What return assumption is reasonable?
For long-horizon retirement projections (20+ years), the academic and industry consensus for US-equity-heavy portfolios is roughly 7% real (after inflation) per year, or 9–10% nominal — based on Robert Shiller's long-run US stock data and Morningstar/Vanguard forecasts. The default in the widget is 7% nominal, which is conservative because it does not bake in the historical equity premium fully. Vanguard's recent capital market assumptions sit in the 4-6% nominal range for US equities over the next decade, reflecting elevated valuations — projections in that range are reasonable for the next 10 years. For 30+ year horizons, 6-7% nominal is a defensible central case. Run the calculator at multiple inputs to see how sensitive your plan is.
Why include the inflation-adjusted balance?
Because future dollars are not worth what today's dollars are worth. A $1 million Roth balance 30 years from now sounds like a lot, but at 2.5% inflation it buys what roughly $475,000 buys today. The nominal projection is what the brokerage statement will eventually show; the real (inflation-adjusted) projection is what the money will actually feel like in purchasing power. Both are useful — the nominal number for setting realistic mental expectations of statement values, the real number for retirement-spending planning.
What does the 4% sustainable withdrawal estimate mean?
The "4% rule" is shorthand for a body of research (originally Bengen 1994, refined by the Trinity Study and subsequent work) suggesting that withdrawing 4% of an initial retirement balance, adjusted upward for inflation each year, has historically had a high probability of supporting a 30-year retirement without depleting the portfolio. It is a rule of thumb, not a guarantee — at high starting valuations and lower expected returns, more recent research suggests a 3.3–3.8% safer rate. The calculator multiplies the projected balance by 4% to give a rough first-order income estimate; treat it as an order-of-magnitude sanity check, not a precise income projection.
Should I contribute to a Roth IRA before maxing my 401(k)?
It depends on the employer match and the relative quality of the 401(k) investment menu. The general hierarchy: 401(k) up to the full employer match first (that is a 50-100% instant return, by far the highest-ROI dollar), then Roth IRA up to the $7,500/$8,600 cap, then 401(k) up to the $24,500/$32,500 cap if you have more capacity. The Roth IRA wins over the 401(k) for the dollars beyond the match because Roth IRAs typically offer much broader investment selection and lower fees than even a good 401(k), and because the Roth tax treatment is structurally favorable. The tax-advantaged hierarchy guide in the investing section walks through the full sequence with bracket-aware math.