Start with principal
Your starting amount gets every month in the projection to compound. A larger base produces more growth dollars at the same percentage return.
Investing
Investment calculator
See what a starting balance and steady monthly contributions could grow into, how much comes from deposits, and how much comes from returns.
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Your investment
Build a growth scenario
Contribution timing
Choose when the monthly deposit reaches the investment. A deposit at the beginning gets one extra month to grow.
Balance over time
Year-by-year investment growth
Deposits build the base. As that base gets larger, the same return rate can add more dollars each year through compounding.
| Year | Starting balance | Contributions | Growth | Ending balance |
|---|---|---|---|---|
| 1 | $20,000.00 | $12,000.00 | $1,569.13 | $33,569.13 |
| 2 | $33,569.13 | $12,000.00 | $2,406.04 | $47,975.17 |
| 3 | $47,975.17 | $12,000.00 | $3,294.58 | $63,269.75 |
| 4 | $63,269.75 | $12,000.00 | $4,237.91 | $79,507.66 |
| 5 | $79,507.66 | $12,000.00 | $5,239.43 | $96,747.09 |
| 6 | $96,747.09 | $12,000.00 | $6,302.69 | $115,049.78 |
| 7 | $115,049.78 | $12,000.00 | $7,431.60 | $134,481.38 |
| 8 | $134,481.38 | $12,000.00 | $8,630.09 | $155,111.47 |
| 9 | $155,111.47 | $12,000.00 | $9,902.50 | $177,013.97 |
| 10 | $177,013.97 | $12,000.00 | $11,253.41 | $200,267.38 |
Know the number
How investment growth works
An investment balance changes through three forces: the money already in the account, the new money you add, and the gains or losses produced by what you own. This calculator holds the return steady so you can see how those pieces interact.
Real returns do not arrive in a straight line. A portfolio may rise one year and fall the next, even when its long-run average is positive. The smooth line here is useful for planning scenarios, but it is not a map of what markets will do.
Add contributions
Regular deposits matter because each one becomes new principal. Automating the contribution can make consistency easier than trying to time a perfect entry.
Let returns compound
Growth stays invested and can produce growth of its own. In a long projection, that compounding share can eventually outweigh what you deposited during the same year.
Investment terms worth knowing
- Principal
- The money already invested before any new return is earned. This calculator calls it the starting amount.
- Rate of return
- The gain or loss on an investment over a period, shown as a percentage of the amount invested.
- Compound growth
- Growth earned on both your deposits and earlier growth. Time gives this effect more chances to repeat.
- Time horizon
- How long the money can stay invested before you expect to need it. A longer horizon can absorb more short-term movement.
- Volatility
- How sharply an investment moves up and down. A smooth average in a calculator does not show the real path returns may take.
- Expense ratio
- An annual fund fee charged as a percentage of assets. Fees reduce the return that reaches your balance.
Different tools, different jobs
Common investment types
The formula accepts one smooth return, but the assets underneath that number behave very differently. Match the risk to when the money is needed, not just to the highest return you can type.
Savings accounts and CDs
Cash products usually trade lower return potential for steadier value and easier access. They can fit emergency funds and near-term goals better than investments that move with a market.
Bonds and bond funds
Bonds lend money to a government or company. Interest rates, credit quality, and maturity all affect their return and price, so they are not risk free even when they move less than stocks.
Diversified stock funds
Index funds, exchange-traded funds, and mutual funds can spread money across many companies. Diversification reduces company-specific risk, but the whole market can still fall.
Individual stocks and alternatives
A concentrated company, property, commodity, or crypto position can move much more than a diversified portfolio. One average-return field cannot capture liquidity, concentration, or total-loss risk.
Use a range
Turn one projection into a better plan
A single ending balance can look certain even when every input is an assumption. Build a range, then focus on the levers you can actually control.
Scenarios worth testing
- Lower return. Test a disappointing market instead of making the plan depend on the best case.
- Higher contribution. Add the amount from a raise or a paid-off debt and see the long-term effect.
- Longer time horizon. One or two more years adds deposits and gives the whole balance more time to compound.
- Higher inflation. Compare the account balance with what that balance may actually buy.
What this tool leaves out
- Market sequence. The same average return can create different outcomes when gains and losses arrive in a different order.
- Taxes and account rules. A 401(k), Roth IRA, and taxable brokerage do not turn the same balance into the same spending money.
- Fees and trading costs. Subtract them from the expected return if you want a closer net estimate.
- Changing deposits. The monthly contribution stays level for the full projection, even though real budgets change.
Common questions
Investment calculator FAQ
What does an investment calculator tell me?
An investment calculator estimates how a starting amount and recurring contributions could grow at an assumed rate over time. The result is a scenario, not a prediction. Use it to compare choices such as saving for longer, contributing more each month, or testing a lower return assumption.
How does compound interest work on investments?
Compounding means each period starts with the deposits and growth accumulated before it. If $10,000 grows 6% in one year, the next year begins with $10,600. Future growth can then be earned on that extra $600 too. Repeating that cycle is why time matters so much.
What expected return should I enter?
Use a rate that fits the kind of investment, its fees, and your time horizon. Cash, bonds, and stocks have different risk and return patterns. Running a lower, middle, and higher scenario is usually more informative than trusting one optimistic number. This calculator does not recommend a rate.
Why do beginning-of-month contributions grow more?
A contribution made at the beginning of the month is present when that month's growth is calculated. A contribution made at the end starts earning in the following month. The difference is one month of growth per deposit, which can add up across a long investment period.
Does compounding monthly mean returns arrive every month?
No. Monthly compounding is a modeling convention that spreads the annual return evenly across 12 periods. Real investments move unevenly and can lose value for months or years. The calculator uses a steady path so the effect of each input is easy to compare.
Why show the result in today's dollars?
Inflation changes what a future dollar can buy. The nominal ending balance is the amount the account could show in the future. The today-dollar figure discounts that balance by the inflation rate you entered, which makes it easier to compare with prices you know now.
Does this investment projection include taxes and fees?
No. Account fees, fund expenses, trading costs, and taxes all reduce what you keep. You can account for recurring fees approximately by lowering the expected return, but taxes depend on the account type, income, holding period, and transactions. A taxable account and a Roth account can finish with different spendable amounts even when their pretax balances match.
Can an investment finish below the amount I contributed?
Yes. Investments can lose value, and a fixed positive return assumption does not display that risk. Short time horizons, concentrated holdings, high fees, and selling during a decline can all produce a result below total deposits. Money needed soon may call for a different risk level than money with decades to remain invested.
The compound growth formula
FV = P(1 + r)n + C x ((1 + r)n - 1) / r
FV is future value, P is the starting principal, C is the monthly contribution, r is the monthly return, and n is the number of months. Beginning-of-month deposits multiply the contribution part by one additional (1 + r).
- Monthly compounding
- Contribution timing modeled
- Inflation-adjusted value
This calculator provides an estimate for education and planning. It is not financial, investment, tax, or legal advice, and it does not predict or guarantee returns. Actual investments can lose value. The projection assumes a fixed return and fixed monthly contribution and excludes taxes, fees, trading costs, and account rules. Consider a qualified professional for guidance about your situation.
Keep the plan moving
The balance gets easier to understand when every account is in view.
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