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Investment Calculator
What your investments grow to with monthly contributions, or the monthly amount needed to reach a goal.
Calculated in your browser – nothing you enter is sent or stored.
This investment calculator shows what your money can grow to with a starting amount, regular monthly contributions and an expected rate of return. Switch to monthly amount for a goal to find how much you need to invest each month to reach a target such as $1 million. Results are shown in future dollars and in today's dollars after inflation, with a year-by-year table and chart.
How to Use the Investment Calculator
- Enter your starting amount and monthly contribution – or choose the goal mode and enter a goal amount.
- Enter how many years you will invest and the expected annual return.
- Optionally increase contributions each year, for example in line with raises.
- Enter inflation to see what the result is worth in today's money.
Example: $500 a Month for 30 Years
Start with $10,000, add $500 a month and earn 7% a year (compounded monthly). After 30 years you have about $691,150. You put in $190,000 – the $10,000 plus $180,000 of contributions – and $501,150, almost three-quarters of the balance, is growth. With 2.5% inflation that is worth about $329,500 in today's dollars.
| $10,000 + $500/month | 20 years | 30 years |
|---|---|---|
| 7% return | $300,851 | $691,150 |
| 10% return | – | $1,328,618 |
The last 10 years add more than the first 20 – that is compounding at work. To reach $1 million in 30 years at 7% with the same $10,000 start, you would need to invest about $753 a month.
What Return Should I Use?
No return is guaranteed, and investments can lose money. Some reference points for long periods:
- U.S. stocks (S&P 500): roughly 10% a year on average over the long run before inflation, with large swings from year to year.
- A balanced 60/40 portfolio of stocks and bonds: historically lower, often assumed at 6%–7%.
- High-yield savings and CDs: about 3%–4.5% in 2026, without market risk – see the CD calculator.
Using 6%–7% gives a cautious plan; check the inflation-adjusted figure, because that is what the money will actually buy.
Ways to Grow Your Investments Faster
- Start early: a 25-year-old who invests for 40 years needs far less per month than a 40-year-old with 25 years.
- Use tax-advantaged accounts: a 401(k) with an employer match and a Roth IRA let more of the growth compound.
- Keep costs low: a 1% yearly fee can cut a 30-year balance by about a fifth.
- Raise contributions each time your pay goes up.
Sources
- SEC Investor.gov – Compound interest calculator and investing basics
- SEC Investor.gov – How fees and expenses affect your investment portfolio
- SEC Investor.gov – What is compound interest?
Last reviewed: October 2026 by the ShrinkBee team. Results are estimates for planning and education, not financial, tax, legal or medical advice.
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