Investment Calculator for Compound Growth, Goals and S&P 500
Investment Calculator
Investment growth over time
Results summary
30 Years investing
| Year | Contributions | Growth | Balance |
|---|---|---|---|
| 1 | $11,200 | $632.65 | $11,832.65 |
| 2 | $1,200 | $742.61 | $13,775.26 |
| 3 | $1,200 | $859.17 | $15,834.43 |
| 4 | $1,200 | $982.72 | $18,017.15 |
| 5 | $1,200 | $1,113.68 | $20,330.83 |
| 6 | $1,200 | $1,252.51 | $22,783.34 |
| 7 | $1,200 | $1,399.65 | $25,382.99 |
| 8 | $1,200 | $1,555.63 | $28,138.62 |
| 9 | $1,200 | $1,720.97 | $31,059.59 |
| 10 | $1,200 | $1,896.23 | $34,155.82 |
| 11 | $1,200 | $2,082 | $37,437.82 |
| 12 | $1,200 | $2,278.93 | $40,916.75 |
| 13 | $1,200 | $2,487.65 | $44,604.40 |
| 14 | $1,200 | $2,708.92 | $48,513.32 |
| 15 | $1,200 | $2,943.45 | $52,656.77 |
| 16 | $1,200 | $3,192.06 | $57,048.83 |
| 17 | $1,200 | $3,455.58 | $61,704.41 |
| 18 | $1,200 | $3,734.92 | $66,639.33 |
| 19 | $1,200 | $4,031.01 | $71,870.34 |
| 20 | $1,200 | $4,344.88 | $77,415.22 |
| 21 | $1,200 | $4,677.56 | $83,292.78 |
| 22 | $1,200 | $5,030.22 | $89,523 |
| 23 | $1,200 | $5,404.04 | $96,127.04 |
| 24 | $1,200 | $5,800.27 | $103,127.31 |
| 25 | $1,200 | $6,220.29 | $110,547.60 |
| 26 | $1,200 | $6,665.51 | $118,413.11 |
| 27 | $1,200 | $7,137.44 | $126,750.55 |
| 28 | $1,200 | $7,637.69 | $135,588.24 |
| 29 | $1,200 | $8,167.95 | $144,956.19 |
| 30 | $1,200 | $8,730.02 | $154,886.21 |
About this investment calculator
This investment calculator is a free tool for estimating compound interest growth, planning savings goals, and testing ideas against historical S&P 500 returns. It is an investment calculator, a compound interest calculator, and an investment growth calculator in one place. It brings three calculators together on one page so you can compare a classic growth projection, a goal focused planner that estimates how many years it may take to reach a target, and an S&P 500 backtest that uses real market history. Enter a starting amount, choose how often you invest, and set an expected annual return. The calculator shows a growth chart and a yearly table so you can see how much value comes from your contributions and how much comes from investment growth. You can also include transaction costs and a Total Expense Ratio to see how fees may reduce long term results.
Calculator modes and use cases
- Classic — Estimate portfolio growth over a fixed number of years based on your return assumption, contribution schedule, and fees.
- Goal — Estimate how many years it may take to reach a target amount and test how changes in contributions or return assumptions move the timeline.
- S&P 500 backtest — Apply historical S&P 500 returns to your plan to see how it would have behaved across past market cycles, then use your assumed return after the last data year.
How the calculations work
The calculator converts the annual return into an effective monthly rate and compounds it each month. Contributions from different frequencies are placed on a monthly timeline so results are comparable. A transaction cost is deducted from each contribution, and the Total Expense Ratio reduces the effective annual return. In Goal mode the calculator evaluates progress year by year until the target is reached or 100 years is reached. In S&P 500 mode it applies historical index returns for the selected years and then switches to your assumed return after the last data year.
Practical guidance for planning
How to interpret the results
The growth chart shows how your total value changes over time and separates your own contributions from investment growth. The yearly table breaks each year into contributions, growth, fees, and ending balance so you can see the path to the final value.
In Goal mode the summary tells you the estimated number of years to reach your target or the highest value reached within 100 years.
Choosing the right mode for your question
- Classic helps you compare scenarios over a fixed period such as saving for a down payment or retirement.
- Goal helps you estimate the time needed to reach a specific target and how much to contribute to get there.
- S&P 500 lets you test the same plan against historical market cycles and then extend it with your own return assumption.
Contributions and increases
Choose monthly, quarterly, or yearly contributions and the calculator converts them to a monthly timeline for compounding. If you increase contributions each year the calculator grows your deposits over time to reflect rising savings capacity.
Why fees change long term results
Transaction costs reduce each contribution before it is invested, while the Total Expense Ratio reduces your effective annual return. Small fees can add up over long periods because the reduced balance also compounds.
How the S&P 500 backtest works
The backtest applies historical S&P 500 performance to your contribution plan for the years you select. This shows how the same behavior would have performed across different market environments.
After the last available data year the calculator switches to your assumed return so you can extend the projection beyond history.
Choosing realistic assumptions
- Use a return assumption that matches your asset mix and time horizon rather than a best case number.
- Consider inflation separately if you want to estimate future buying power.
- Adjust contributions until the plan feels realistic for your monthly budget.
Example you can model
Start with $10,000, invest $250 per month, assume a 6 percent return, add a 0.20 percent TER, and compare 20 years in Classic with the Goal timeline. Then switch to the S&P 500 mode to see how the same plan would have performed in past decades.
Notes and limits
- This calculator is for education and planning and does not provide financial advice.
- Taxes, bid ask spreads, and account specific rules are not included.
- Results are estimates and real markets can differ from any model.
Learn more
Visit the Investment Guide for deeper explanations, examples, and common investing mistakes.