What your savings grow to
Enter what you have, what you add each month, and a return. Inflation shows buying power in today's dollars.
- Starting amount$10,000.00
- Deposits (240 months)$120,000.00
- Growth from returns$162,465.03
- Value in today's dollars (3% inflation)$161,930.80
- Future value$292,465.03
How investment growth works
Money invested earns returns, and those returns earn returns of their own. That is compounding. Adding money every month speeds up the process, because each deposit starts growing right away.
Returns here are an assumed yearly rate that stays the same. Real investments move up and down, so treat results as a planning range. For the pure compounding math, see the compound interest calculator. To plan for independence, try the FIRE calculator.
Worked examples
| Years | Value | You put in | Today's dollars (3% inflation) |
|---|---|---|---|
| 10 | $85,525.87 | $60,000 | $63,639.28 |
| 20 | $253,768.19 | $120,000 | $140,505.29 |
| 30 | $584,726.30 | $180,000 | $240,899.49 |
The first 10 years add $85,525.87. The last 10 years add about $331,000, since growth builds on a larger base. Time is the strongest lever in the model.
Reaching $500,000 from $10,000 with $500 a month at 7% takes 26 years and 6 months. To hit $1,000,000 in 30 years from zero, the monthly deposit is $855.10.
Future dollars vs today's dollars
Prices rise over time, so a dollar in 20 years buys less than a dollar today. The calculator shows both numbers: the future value in future dollars, and the same amount adjusted by your inflation assumption. At 3% a year, $292,465.03 in 20 years buys what about $161,930.80 buys today.
Common mistakes
- Treating an assumed return as a promise. Real returns are uneven and can be negative.
- Ignoring inflation. A big future number may buy less than it seems.
- Forgetting fees and taxes, which reduce the real return.
- Waiting to start. Early deposits have the longest time to grow.
Frequently asked questions
How much will $500 a month grow to in 20 years?
At an assumed 7% a year from a $10,000 start, it grows to $292,465.03. Without a starting amount, $500 a month reaches $253,768.19. Real returns vary, so treat the number as a scenario.
How do I calculate investment growth with monthly contributions?
Grow the starting amount by the monthly rate for each month and add the deposit at the end of each month. The closed form is start × (1 + r)^n plus deposit × ((1 + r)^n − 1) ÷ r.
How long to save $500,000 investing $500 a month?
Starting with $10,000 and earning an assumed 7% a year, it takes 26 years and 6 months. A higher return or a bigger deposit shortens the time.
How much do I need to invest each month to reach $1 million?
To reach $1,000,000 in 30 years from zero at an assumed 7% a year, deposit $855.10 a month. Use the Monthly amount needed tab for your own goal.
What is the difference between nominal and real investment value?
Nominal is the dollar amount you will have. Real is that amount adjusted for inflation, so it shows buying power in today's dollars.
What return should I use?
No one can know the future. Use a cautious number, and test a low and a high case. The 7% in the examples is only an assumption.
Sources and review
- Standard future value of an annuity formula with monthly compounding