📈 Compound Interest Calculator
Estimate how savings and recurring contributions grow over time with compound returns.
Investment Growth Calculator
Use this free investment growth calculator to project how a portfolio can grow with consistent investing and compounding. It targets searches like investment calculator, portfolio growth calculator, and how much will I have if I invest every month.
Interactive calculator
$
$
% / yr
years
Portfolio Value
$512,214
Investment Gains
$357,214
Total Invested
$155,000
Gain %
230.5%
Portfolio growth over 25 years
Value Contributions
How the math works
Formula
FV = PV(1 + r)^t + PMT × [(1 + r)^t − 1] / r
- FVFuture portfolio value
- PVStarting portfolio value
- rAnnual return rate as a decimal
- tInvestment horizon in years
- PMTAnnual contribution
Plain English
This is the same compound growth principle applied annually. Starting early matters more than starting large: $5,000/year from age 25 at 8% grows to about $1.4M by 65 — while $10,000/year starting at age 45 only reaches $495,000 by 65, despite more total dollars contributed.
How to use this calculator
- 1
Enter your starting investment, monthly contribution, annual return assumption, and number of years.
- 2
Review the projected ending portfolio value and the amount attributable to gains.
- 3
Run multiple scenarios with higher or lower contributions and return assumptions.
Why this number matters
Investors often focus on return percentages without modeling the actual path of contributions and time. This calculator makes it easier to compare scenarios and set realistic expectations for wealth accumulation, retirement, and milestone targets.
What this calculator helps you answer
- •How much could I have if I invest $500 per month for 25 years?
- •How much of my ending balance comes from gains versus deposits?
- •How sensitive is my portfolio outcome to different return assumptions?
Frequently asked questions
What is the difference between compound interest and investment growth?+
They are closely related. Investment growth typically models portfolio returns with recurring contributions, while compound interest often focuses on the broader compounding concept.
Should I use nominal or inflation-adjusted returns?+
For purchasing power planning, inflation-adjusted returns are more realistic. For nominal account balance projections, use expected nominal returns.
Can this calculator predict actual market returns?+
No. It is a planning tool based on assumptions. Real market returns are uneven and can differ significantly from a constant annual estimate.
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