Enter a starting amount, a monthly contribution, an annual rate of return you want to test, a number of years and a compounding frequency. The tool shows the hypothetical ending balance, how much of that came out of your own pocket, and how much is growth — then runs the identical scenario a second time with an annual fee deducted, so you can see what that fee costs over the same horizon in dollars. The rate of return is an assumption you are choosing to test. It is not a forecast by us, and no return is guaranteed.
The return rate below is your assumption, not our projection. Whatever you type is the rate the arithmetic assumes for every single year, with no losing years in it, which is not how investing works. Treat the output as a way of testing an assumption, not a number to plan around. Run it low, run it high, and see which conclusions survive both.
Your scenario
Hypothetical illustration at your assumptions
The same scenario, with the annual fee taken out
Read the last three rows together, because that is the part people miss. The fee dollars deducted are the small number. The gap between the two ending balances is the larger one, and the difference between them is growth those fee dollars never got to earn. A fee is not a one-off charge; it is a permanent reduction in the rate at which the balance compounds. The long version is here.
That default is our own fee. Aduna Capital charges 1.5% to 2.0% of assets per year for investment management, published on our fee page and in our Form ADV Part 2A — so the number this page shows you by default is what we would cost you, not what some cheaper hypothetical firm would. The point is not that low fees are always right — it is that a fee is a real, compounding cost, so you should know its size and decide for yourself whether what you get back is worth it.
Year by year, so the arithmetic is inspectable
Every year for the first ten, then every fifth year, plus the final year. Nothing here is hidden in a black box — you can check any row by hand.
| Year | Contributed to date | Balance, no fee | Balance, after fee | Difference |
|---|
Assumptions used — read these before trusting the number
- The return is constant and positive every year. That is the biggest lie in every compound interest calculator, this one included. Real returns arrive out of order, and the order matters enormously once you are withdrawing — see sequence-of-returns risk.
- Contributions are added at the start of each month; a period’s growth is credited at the end of that period on the balance then in the account. With annual compounding this treats a December contribution as though it had been there all year, which flatters the result slightly. Real accounts credit dividends and interest on their own schedules.
- The monthly contribution never changes. No raises, no inflation indexing, no catch-up contributions, no years you skip. Increasing the contribution with your pay usually matters more than any other input on this page.
- The fee is deducted monthly at one twelfth of the annual rate. Advisory fees are more often billed quarterly and expense ratios accrue daily; that convention difference is small next to the size of the fee itself.
- No taxes. Not on dividends, interest, gains or withdrawals. In a taxable account that is a material omission, and in California a larger one — see California tax and investing.
- No inflation. A balance thirty years out will buy meaningfully less than the same number does today. For a real return, subtract your inflation assumption from the rate you enter.
- No employer match, no fees other than the one you enter, no trading costs, no cash drag, no rebalancing, no contribution limits enforced. For 2026 those limits are $24,500 of 401(k) elective deferral (plus an $8,000 catch-up at 50 and over, or $11,250 at ages 60 to 63) and $7,500 to an IRA or Roth IRA (plus $1,100 at 50 and over). Source: IRS Notice 2025-67. Which account first →
- Nothing here is a recommendation to buy, sell or hold any security, or to save any particular amount. It is arithmetic on figures you supplied.
This is an estimate, not advice. The output above is arithmetic performed on the numbers you entered, under the assumptions printed on this page. It is not a recommendation, not a projection you should rely on, and not a substitute for a conversation with your CPA or a qualified adviser about your own situation.
Common questions
Does the compounding frequency really matter?
Far less than people expect. Switch the selector from annual to monthly at the same rate and horizon and the ending balance barely moves. Now shift the fee field by half a percentage point and watch what happens. The selector is here mainly so you can see how little it changes.
What return should I put in the box?
We are not going to give you one. A rate printed by a firm that also manages money sits uncomfortably close to a performance claim, and it is a claim nobody can stand behind. Run several rates and see which conclusions hold across all of them. If a plan only works at one optimistic rate, it is not a plan.
Why does a 1% fee take so much more than 1% of the ending balance?
Because it is charged every year, on a balance that would otherwise have kept growing. The fee dollars leave, and the growth those dollars would have produced leaves with them, and that missing growth compounds for the rest of the horizon. That is the gap between the “fee dollars actually deducted” row and the “difference” row above. Longer horizons make the gap wider.
So should I just buy the cheapest thing available?
Not necessarily, and this tool does not say so. Cost is one side of the ledger; what you receive for it is the other. What the arithmetic establishes is that the cost is real, compounding and permanent, so it deserves to be measured rather than ignored. Our fee analyzer goes further.
Want this run against your actual accounts?
Your real contributions, your real fund expense ratios, your real tax picture and your real horizon — not a smooth line on a web page. Fee-only, fees published, $0 to open and $50 a month ongoing, nothing to sell you.