Investment Calculator
Use this Investment Calculator to estimate how money may grow over time with compound interest, monthly contributions, inflation adjustment, and goal planning.
Background
Investing growth usually comes from two sources: the money you contribute and the growth earned on that money. Over long periods, compound growth can become a major part of the final balance because returns may earn returns of their own.
How to use this calculator
- Choose the investment calculation mode that matches your question.
- Enter your starting amount, monthly contribution, return assumption, inflation assumption, and time horizon or target balance.
- Click Calculate to see the estimated future value, contribution breakdown, inflation-adjusted value, chart, table, and step-by-step explanation.
How this calculator works
- For future value mode, it combines the future value of the starting amount with the future value of monthly contributions.
- For one-time investment mode, it compounds only the starting amount over time.
- For monthly goal mode, it estimates the monthly contribution needed to reach a target balance by a chosen date.
- For time to goal mode, it simulates month by month until the target balance is reached.
- For scenario comparison mode, it runs the same investment plan under conservative, expected, and aggressive return assumptions.
Formulas & Rules Used
Monthly rate: r = annual return ÷ 12
Starting amount future value: FV = PV × (1 + r)^n
Monthly contributions, end of month: FV = PMT × [((1 + r)^n − 1) ÷ r]
Monthly contributions, beginning of month: FV = PMT × [((1 + r)^n − 1) ÷ r] × (1 + r)
Inflation-adjusted value: Today’s value = future value ÷ (1 + inflation)^years
Example Problems & Step-by-Step Solutions
Example 1 — Future value with monthly contributions
- Start with the initial investment.
- Add the monthly contribution every month.
- Apply the monthly equivalent of the expected annual return.
- Repeat for the full investment period.
- Separate the final balance into contributions and estimated growth.
Example 2 — Monthly contribution needed for a goal
- Choose the target balance and investment period.
- Estimate how much the starting amount may grow by itself.
- Calculate the remaining balance that contributions must cover.
- Solve for the monthly contribution needed to reach the goal.
Example 3 — Inflation-adjusted result
- Calculate the future investment balance.
- Estimate how prices may rise over the same period.
- Divide the future balance by the inflation factor to estimate purchasing power in today’s dollars.
Frequently Asked Questions
Q: Is this investment calculator a guarantee?
No. It is an educational estimate. Real investment returns can vary, and investments can lose value.
Q: Why does monthly investing help?
Monthly investing adds more principal over time and gives each contribution a chance to compound.
Q: What is compound interest?
Compound interest means growth can be earned on both the original money and earlier growth.
Q: What does inflation-adjusted value mean?
It estimates what the future balance may be worth in today’s purchasing power after accounting for rising prices.
Q: Should I use the conservative, expected, or aggressive scenario?
Use all three to understand a range of possible outcomes. A single return assumption can make the future look more certain than it really is.
All calculators