Invest 500 a Month: What It Grows To in 10, 20, 30 Years

Invest 500 a month at a 7% average return and you end with about 86,500 after 10 years, 260,000 after 20 and 610,000 after 30. Your own money in those pots is 60,000, 120,000 and 180,000, and the math is the same in dollars, euros or pounds. With a 0.2% fund fee and 2.5% inflation, the 30-year pot is worth about 280,000 in real terms.

Drop the return to 5% and the 30-year pot is 416,129. Pay 1.5% a year for an active fund instead of 0.2% for a world ETF and it ends about 130,000 lower.

What 500 a month grows to: the table

How compound interest works walks through the formula. The free compound interest calculator uses the same method, so you can run your own numbers there, no sign-up.

MFFT computation: 0 start, 500 a month deposited at month end, annual rate divided by 12 each month, no fees, nominal.

Put in 6,000 once at the end of each year instead of 500 a month, and 7% gives 566,765 after 30 years rather than 609,985, because each monthly 500 starts compounding the month it lands.

Investing for 30 years instead of 20 at 7% takes 60,000 more of your own money and ends 349,522 higher.

Data: MFFT computation; 500 a month, end-of-month deposits, monthly compounding, 7% return, no fees, no inflation.

Which return should you assume?

Since 1928 the S&P 500 with dividends has returned a geometric average of 10.02% a year through 2025, nominal and for the US only, using Aswath Damodaran's annual return table. The UBS Global Investment Returns Yearbook 2026 puts US equities at 6.6% a year after inflation over 1900-2025, and the UBS press release gives developed-market equities as a group 8.5% a year since 1900.

A world ETF holds the US plus Europe, Japan and the rest, so it won't track the S&P 500 year by year. In 2022 the MSCI World index fell 18.1%, according to the iShares Core MSCI World factsheet page. The same Damodaran series includes years like 1931 (-43.84%) and 2008 (-36.55%).

What fees and inflation leave you

The iShares Core MSCI World charges 0.20% a year and the Vanguard FTSE All-World UCITS ETF 0.14%, as of November 2026. For active equity funds sold to EU retail investors, ESMA's 2025 cost report found ongoing costs of 1.39% a year over a 10-year horizon, against 0.26% for equity ETFs, with entry fees on top.

The 2.5% inflation figure sits a little above the 2% targets of the ECB (over the medium term) and the Federal Reserve (over the longer run).

MFFT computation: 500/month, 7% gross return minus the fee (0.2% for a world ETF, 1.5% for an active fund); after inflation = nominal divided by 1.025 to the power of the years.

The gap between the two fees is 5,843 after 10 years, close to a full year of deposits, then 129,646 after 30 years and 370,441 after 40.

Eurostat's flash estimate put euro-area inflation at 4.0% in October 2026, well above 2.5%, and the US Bureau of Labor Statistics reported CPI up 3.7% in the 12 months to September. If prices averaged 3.5% for the whole 30 years, the same 586,452 would be worth about 209,000 after inflation instead of 279,587. In the calculator, try 2.5 and then 3.5 in the inflation field and compare.

Data: MFFT computation; 500 a month, end-of-month deposits, monthly compounding, 7% gross return, fees 0%, 0.2% and 1.5%, inflation 2.5%.

When monthly growth passes the 500 deposit

At 7%, the growth earned in a single month first beats your 500 deposit in month 121, when the balance is 86,542, just after year 10. Counted by calendar year, year 10 earns 5,613 against the 6,000 you put in. Year 11 earns 6,452, the first full year in which growth exceeds the 6,000 deposited. At 5% it takes until month 168, at the end of year 14. Total growth only exceeds total deposits in year 19 at 7%, and in year 26 at 5%.

Data: MFFT computation; 500 a month, end-of-month deposits, monthly compounding, 7% return, no fees, no inflation.

In year 3 at 7% the whole pot earns 1,125 in growth, while raising the transfer from 500 to 600 adds 1,200 that year, so early on the size of the deposit moves the balance more than the return does. The post on savings rate vs investment returns works out when returns take over from deposits.

With the same 500 a month run through actual S&P 500 years from Damodaran's annual S&P 500 returns, a saver who started in 1989 had 313,025 at the end of 2007 and 203,527 a year later, after the -36.55% year, about 110,000 less, with 120,000 deposited in total. A saver who started in 1999 ended 2018 at 273,601, about 25% above a smooth path at the same 5.57% average return, because the monthly deposits made through the 2000-2002 and 2008 crashes bought shares at low prices.

Is investing 500 a month enough?

Someone who starts at 35, puts 500 a month into a 0.2% fund and earns 7% gross reaches 65 with 279,587 after 2.5% inflation. Under the 25x rule (the inverse of a 4% withdrawal rate) that supports about 11,200 a year, roughly 930 a month on top of any state pension. Starting at 25, 462,172 supports about 18,500 a year.

MFFT computation: 500/month to age 65, 7% gross return, 0.2% fee, after inflation at 2.5%.

To check your own case, multiply the yearly spending you'd need in retirement by 25 and compare it with the after-inflation column for your starting age. How much you should save for retirement works backwards from that spending figure to a monthly amount.

Where to put 500 a month

The whole 500 can go into one broad world ETF, such as the Vanguard FTSE All-World at 0.14% or the iShares Core MSCI World at 0.20%. Pick the accumulating share class so dividends are reinvested, and set the broker's savings plan to buy on payday.

Once a year, put a date in your calendar to lift the monthly transfer by at least the 2.5% inflation used in these numbers. Increasing your monthly investment every year shows what those yearly steps do to the end balance.

For cash you already hold, the lump sum vs dollar-cost averaging calculator compares putting it in at once with spreading it out.

Run it with your own numbers

Open the compound interest calculator and type: starting balance 0 (or what you already have), monthly contribution 500, years 30, annual return 7, inflation 2.5. Under "Show advanced (fund fees)" enter your fund's expense ratio: 0.2 for a world ETF, or whatever your bank fund actually charges. Then switch on the real (inflation-adjusted) view. Change one input at a time (return to 5, inflation to 3.5, years to 20) and note the year your growth passes your deposits in its year-by-year table.