Investment Calculator
$
$
8.00%
30 yrs
Future Value$854,537.02
Total Contributions$190,000.00
Total Returns$664,537.02
- Total Balance
- Contributions
This investment calculator projects how a portfolio grows when you combine an initial stake with steady monthly contributions and a compounding annual return. It separates the ending balance into the money you put in versus the gains the market provided, making the power of compounding easy to see. A year-by-year timeline shows the balance climbing as contributions and returns stack up over your horizon.
Formula
FV = P(1+r/12)^(12t) + PMT·[((1+r/12)^(12t) − 1)/(r/12)]
- P
- Initial investment
- PMT
- Monthly contribution
- r
- Expected annual return as a decimal
- t
- Number of years invested
How it works
- Enter your initial investment, the monthly contribution you plan to add, the expected annual return, and the number of years you will stay invested.
- The calculator compounds monthly: it grows the initial stake and treats each monthly contribution as an end-of-month deposit that compounds for the remaining months.
- It reports the future value, the total of everything you contributed, and the investment returns, which are simply the future value minus those contributions.
Worked example
Invest $10,000 upfront and $500 per month for 20 years at a 7% annual return.
- Months: 12 × 20 = 240; monthly rate = 0.07 ÷ 12 ≈ 0.0058333.
- Initial stake grows: 10,000 × (1.0058333)^240 ≈ $40,387.39.
- Contributions grow: 500 × ((1.0058333)^240 − 1) ÷ 0.0058333 ≈ $260,463.33.
- Total contributions: 10,000 + 500 × 12 × 20 = $130,000, so returns = 300,850.72 − 130,000 = $170,850.72.
Future value about $300,850.72, with $130,000 contributed and $170,850.72 earned as investment returns.
Frequently asked questions
- How does this differ from a future value calculator?
- They share the same compounding math, but this tool is framed around investing: it always compounds monthly and breaks the result into total contributions versus market returns to highlight how much of your balance is growth.
- Is the expected return guaranteed?
- No. The expected return is an assumption you choose, and real markets fluctuate year to year. Use a conservative figure and treat the projection as a planning estimate rather than a certainty.
- Are the monthly contributions adjusted for inflation?
- No. Contributions are treated as a constant nominal amount, and the future value is in nominal dollars. To see purchasing power, adjust the result separately with an inflation calculator.
- When are contributions added each month?
- Each contribution is treated as an end-of-month deposit, so the most recent contribution earns no return in its final month. This ordinary-annuity assumption matches how most automated investment plans are modeled.