Do these numbers assume a 401(k), an IRA, or a taxable account?

None specifically — the projection is account-agnostic compounding math. Account type changes taxes, contribution limits, and whether an employer match exists, but the growth arithmetic of a monthly deposit at an assumed return is the same everywhere. Taxes and fees will reduce what you keep, which is one more reason to treat the output as an estimate.

What if I already have savings — do I still need the full monthly amount?

No. An existing balance compounds for the entire period and replaces part of the required deposit. The from-scratch figures here are the worst case; enter your actual balance in the calculator and the required monthly amount falls, often substantially if you are young.

Is 7% a safe return to assume?

It is a common planning assumption drawn from long-run U.S. stock averages before inflation, not a safe promise. Diversified portfolios with bonds have historically earned less, and any given decade can land well above or below the average. Running the projection at a couple of lower rates is the honest way to see your range of outcomes.

Why is my required amount higher in inflation-adjusted terms?

Because holding purchasing power steady is a harder goal than hitting a nominal number. Using a real return (the assumed return minus expected inflation) makes the engine target $1 million in today's buying power, which at an illustrative 4% real return takes $846.05 a month over 40 years instead of $380.98.

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How much do I need to save each month to retire with $1 million?

By RetireLab · Published June 10, 2026 · Updated June 10, 2026

At an assumed 7% annual return with no starting balance, reaching $1 million by age 65 takes about $380.98 a month starting at 25, $819.69 a month starting at 35, or $1,919.66 a month starting at 45.

The answer at three starting ages

All three figures come from the RetireLab projection engine, which compounds monthly and adds each deposit at the end of the month. With nothing saved yet and an assumed 7% annual return, a 25-year-old who deposits $380.98 a month for 40 years is projected to finish at $1,000,001.41. A 35-year-old needs $819.69 a month for 30 years to land at $999,998.03. A 45-year-old needs $1,919.66 a month for 20 years to reach $1,000,002.07.

These are projections from a level deposit and a constant assumed return, not a guarantee — real markets do not return the same percentage every year, and your actual path will wobble around any smooth curve. Treat the monthly amounts as planning estimates to react to, not a promise, and re-run them whenever your situation or assumptions change.

Why waiting ten years more than doubles the bill

Moving the start date from 25 to 35 raises the required deposit from $380.98 to $819.69 — about 2.15 times as much. Waiting until 45 raises it to $1,919.66, roughly 5 times the 25-year-old's number. The penalty is steeper than the lost years alone suggest because the dollars you skip are the ones with the longest time to compound: a deposit made at 25 has 480 months of growth ahead of it, while one made at 45 has at most 240.

The same effect shows up in total out-of-pocket cost. The 25-year-old contributes $182,870.40 across the 40 years; the 35-year-old pays in $295,088.40; the 45-year-old pays $460,718.40 — two and a half times the early starter's total for the same $1 million finish line. Starting early does not just lower the monthly payment, it shrinks the entire lifetime bill.

Who actually builds the million — you or compounding

Splitting each projected balance into deposits and growth makes the head start visible. For the 25-year-old, $817,131.01 of the final balance is investment growth — almost 82 cents of every dollar. For the 35-year-old, growth supplies $704,909.63, about 70%. For the 45-year-old, growth contributes $539,283.67, just under 54%, with deposits doing nearly half the work.

That share is the practical meaning of "time in the market." The early starter recruits compounding as the senior partner and personally funds less than a fifth of the target; the late starter has to be the senior partner themselves. If the monthly figure for your age looks heavy, the levers in rough order of power are starting sooner with any amount, raising the deposit later, and retiring a little later.

The nominal-versus-real caveat

Every figure above is nominal — it counts future dollars, and a million of them in 2066 will not buy what a million buys today. Consumer prices have historically risen a few percent a year, so a 7% market return might translate to roughly 4% of real purchasing-power growth. If you want $1 million in today's dollars, run the projection at a real return instead of a nominal one.

At an illustrative 4% real return, the engine says the 40-year saver needs $846.05 a month, the 30-year saver needs $1,440.82, and the 20-year saver needs $2,726.47 — in each case more than double the nominal-target deposit. Neither framing is wrong; they answer different questions. The nominal numbers hit a headline figure, while the real numbers hold its buying power steady.

What can shrink these monthly numbers

The scenarios assume you start from zero and save alone. Any existing balance compounds the whole way and directly reduces the required deposit, so enter your real starting balance in the calculator rather than using the from-scratch figures. An employer match helps even more: every matched dollar is a deposit you did not have to make, and the 401(k) view of the calculator adds the match to the projection automatically.

The assumed return matters as much as any deposit decision. These examples use 7% because it sits inside the historical long-run range for U.S. stocks before inflation, but a conservative mixed portfolio may earn less and any single decade can stray far from the average. Checking the required deposit at 5% and at 9% shows how wide the realistic band around "about $381 a month" actually is.

Turning the target into your own plan

One million dollars is a clean benchmark, not a personal verdict. The classic 4% rule of thumb would draw roughly $40,000 in the first year from a $1 million balance, which may be plenty alongside Social Security for one household and thin for another. Work backward from the yearly income you want, then size your own target before fixating on the round number.

From there, the calculator does the iteration for you: enter your age, balance, and deposit, then nudge the deposit until the projection crosses your target. These results are estimates for planning, not financial advice — revisit the inputs after raises, market swings, or a change in your retirement date, and bump your deposit when the projection drifts below the line.

Questions

Do these numbers assume a 401(k), an IRA, or a taxable account?: None specifically — the projection is account-agnostic compounding math. Account type changes taxes, contribution limits, and whether an employer match exists, but the growth arithmetic of a monthly deposit at an assumed return is the same everywhere. Taxes and fees will reduce what you keep, which is one more reason to treat the output as an estimate.
What if I already have savings — do I still need the full monthly amount?: No. An existing balance compounds for the entire period and replaces part of the required deposit. The from-scratch figures here are the worst case; enter your actual balance in the calculator and the required monthly amount falls, often substantially if you are young.
Is 7% a safe return to assume?: It is a common planning assumption drawn from long-run U.S. stock averages before inflation, not a safe promise. Diversified portfolios with bonds have historically earned less, and any given decade can land well above or below the average. Running the projection at a couple of lower rates is the honest way to see your range of outcomes.
Why is my required amount higher in inflation-adjusted terms?: Because holding purchasing power steady is a harder goal than hitting a nominal number. Using a real return (the assumed return minus expected inflation) makes the engine target $1 million in today's buying power, which at an illustrative 4% real return takes $846.05 a month over 40 years instead of $380.98.