A million dollars is an arbitrary round number, but it is a useful one: it maps to roughly $40,000 of annual spending at a 4% withdrawal rate, and it is large enough that the arithmetic of reaching it is instructive.
This guide shows the monthly contribution required across different horizons and return assumptions, explains what changes the answer, and covers what to do when the required figure is out of reach.
What the Monthly Deposit Needs to Be
Rearranging the future value of an annuity for the payment gives the required deposit:
PMT = FV × (r/n) ÷ [(1 + r/n)nt − 1]
With FV of $1,000,000, a 7% nominal return and monthly compounding, the figures work out as follows. All rows assume no starting balance.
| Years invested | At 5% return | At 7% return | At 9% return |
|---|---|---|---|
| 10 years | $6,440/mo | $5,780/mo | $5,170/mo |
| 20 years | $2,430/mo | $1,920/mo | $1,500/mo |
| 30 years | $1,200/mo | $820/mo | $550/mo |
| 40 years | $655/mo | $380/mo | $215/mo |
Two observations do most of the work. First, the horizon dominates: moving from 20 years to 30 at 7% cuts the required deposit by 57%, while moving from 7% to 9% over 20 years cuts it by 22%. Second, the total amount you personally deposit falls dramatically as the horizon lengthens — $460,800 over 20 years at 7%, but only $182,400 over 40.
Test your own numbers, including any balance you already hold, in the compound interest calculator.
Four Things That Change the Answer
- An existing balance. A $50,000 starting portfolio at 7% for 30 years becomes roughly $406,000 on its own, cutting the required monthly deposit from about $820 to around $490.
- Employer contributions. Match and profit-sharing contributions count toward the same target. A 5% employer match on a $70,000 salary is $292 a month you do not have to find.
- Inflation. $1 million in 30 years buys roughly what $412,000 buys today at 3% inflation. If the goal is a million in today's purchasing power, use a real return of about 4% instead of 7% — which raises the 30-year requirement to roughly $1,440 a month.
- Contribution growth. Increasing deposits with your salary changes the picture substantially. Starting at $500 a month and raising it 3% a year reaches about $895,000 over 30 years at 7%, versus $610,000 for a flat $500.
When the Required Amount Is Out of Reach
If the number in the table is larger than your entire disposable income, the target is not wrong — the framing is. Four adjustments, in order of usefulness:
- Extend the horizon. This is by far the strongest lever because time carries the exponent. Five additional years at 7% reduces a 25-year requirement by roughly a third.
- Question the target. A million is only meaningful relative to spending. A household spending $32,000 a year needs about $800,000 at a 4% withdrawal rate; one spending $60,000 needs $1.5 million. Set the number from your actual budget.
- Start with any amount and escalate. $200 a month for 40 years at 7% still produces about $525,000. Beginning small and raising the figure annually beats waiting for the "correct" amount.
- Raise income before cutting further. Below a certain point, expense reduction has a floor while income does not. A $6,000 annual raise fully invested adds $500 a month to the plan.
A realistic sanity check
A household investing 15% of a $90,000 combined income contributes $1,125 a month. At 7% over 30 years that reaches about $1.37 million nominal, or roughly $565,000 in today's purchasing power. That is a solid outcome, and it is also a reminder to read every seven-figure projection in real terms before celebrating it.