Roth IRA Growth Calculator
Roth IRA growth is what annual contributions compound to inside an account whose qualified withdrawals are not taxed. Contributions are made with money already taxed, so the value of the wrapper is the growth — and on a long horizon the growth is most of the balance.
What the wrapper is worth
Defaults are $7,000 contributed each year for 30 years at an assumed 7%.
Contributions are assumed at the end of each year, which is the conservative convention. Annual contribution limits and income eligibility are set by statute and change — check the current figures before using them as inputs.
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How the number is built
The arithmetic is an ordinary annuity. What makes it a Roth question is which part of the answer is taxable, and on a long horizon the untaxed part is most of it.
Balance = contribution × ((1 + r)^n − 1) ÷ r
Every contribution compounds only from the year it arrives. The first one has 30 years to work and the last has none, which is why the early years matter far more than they feel like they do.
A worked example
Take the defaults: $7,000 a year for 30 years at an assumed 7%.
You contribute 7,000 × 30 = 210,000.
The balance is 661,226.
So 451,226 is growth — 68% of the final balance is money nobody contributed, and in a qualified Roth withdrawal that portion is not taxed.
That 451,226 is the whole case for the wrapper, and it is why the account gets more valuable the longer it is left alone rather than the more that is put in.
Time is the input that matters
Run the same contribution over different horizons and the sheltered share changes shape.
Over 10 years, $7,000 a year reaches 96,715 against $70,000 contributed — growth is 28% of it.
Over 20 years it reaches 286,968 against 140,000 — growth is 51%.
Over 30 years it reaches 661,226 against 210,000 — growth is 68%.
Which means a short horizon shelters very little. The tax advantage is not a feature you switch on; it is something that accumulates, and it accumulates slowly at first.
Which end you pay at
The comparison people want is against a pre-tax account, and it has one clean form. Contribute the same nominal amount to each, and the pre-tax version ends with the same 661,226 — but that balance is taxable on withdrawal, while the Roth balance is not.
At a 22% rate in retirement, the pre-tax 661,226 nets 515,756. At 12% it nets 581,879. At 32% it nets 449,634. The Roth number does not move, because the tax was settled on the 210,000 rather than on the 661,226.
So the whole question is which rate is higher: yours now, or yours then. A Roth wins when the later rate is higher and loses when it is lower, and nobody knows their future bracket — which is the honest reason for holding some of each rather than a hedge against having to decide.
What the rules actually restrict
Three separate restrictions apply and they are often confused. There is an annual contribution limit, an income range above which direct contributions phase out, and conditions a withdrawal must meet to be qualified. All three are set by statute and revised, so treat any figure you read — here or anywhere — as needing a check against the current year.
Contributions and growth are treated differently on the way out. Contributed amounts have already been taxed and can generally be withdrawn; growth is the part with conditions attached. This is educational, not tax advice, and the treatment depends on your circumstances.
What erodes it
A tax wrapper does not shelter you from fees. On this site’s arithmetic, 20 basis points a year removes 5.8% of a thirty-year pot, 75 removes 20.2% and 150 removes 36.5%. On the default balance, 75 basis points is roughly 133,000.
Trading inside the account is free of tax and not free of cost. The spread and the commission are charged the same as anywhere.
The original data
Of the 24,971 unique videos in this site’s search study, 24 have Roth IRA in the title, at a median of 95,293 views across 15 channels — and 4% are calculator-shaped. The 401k appears in 22 at 81,626 and retirement targets in 17 at 87,636.
Twenty-four videos at a 95,293 median and almost none of them a calculator. The subject that gets covered is eligibility; the number people actually want is what the sheltered growth becomes.
The question: Contribute now, or wait until income is higher?
The answer is that waiting costs a year of compounding you cannot buy back later. Contribution limits are annual and do not carry forward, so a skipped year is gone. And a higher income can put direct contributions out of reach entirely — the eligibility range runs the opposite way to the intuition that earning more makes saving easier.
When it fails
The failure this calculator cannot show is that the growth might not arrive. A wrapper that exempts growth from tax is worth exactly nothing on a balance that did not grow, and a decade of flat returns leaves you having paid tax up front for a benefit that never materialized. The smooth 7% line hides that entirely, and it is the honest limit of the arithmetic rather than a footnote to it.
The second failure is assuming your tax rate will be higher later. A Roth wins if it is and loses if it is not, and nobody knows.
A third is treating the limits as fixed. They are revised and eligibility phases out by income.
A fourth is contributing without investing. Cash in a Roth shelters nothing.
A fifth is ignoring fees. The wrapper does not exempt you from them.
And a sixth is withdrawing growth early. That is the part with conditions, and the penalties are the mechanism the whole shelter depends on.
Related
Roth IRA covers the account’s rules in full. Compound interest is the engine producing the untaxed portion. And index funds is what the balance is usually invested in.
The helpful reframe is that you are not choosing between paying tax and not paying tax — you are choosing which end to pay it at. A Roth pays now on a small number, and a pre-tax account pays later on a much larger one. Which is better depends on rates you cannot know, which is why holding some of each is a reasonable answer rather than an indecisive one.
— Michael Whitman
This page is educational, not financial advice. Test every idea on your own charts before risking money.