Investment Calculator
Project how your investments grow over time with compound returns, recurring contributions, and customizable compounding frequency.
Investment Growth Calculator
Estimate future portfolio value from a starting balance, monthly contributions, and expected annual return.
Formulas
FV = P(1 + r/n)nt + PMT × [((1 + r/n)nt − 1) / (r/n)]
How to use this investment calculator
- Starting amount: Enter your current portfolio balance or initial lump-sum investment.
- Return & timeline: Set the expected annual return rate and number of years to project.
- Contributions: Add a monthly contribution amount and choose whether deposits occur at the beginning or end of each period.
- Review results: See ending balance, a breakdown donut chart, and annual or monthly accumulation schedules.
Investment growth formulas
A = P(1 + r/n)nt + PMT × [((1 + r/n)nt − 1) / (r/n)]
Where P is the starting principal, PMT is the periodic contribution, r is the annual rate (decimal), n is compounding periods per year, and t is years.
Example: $20,000 starting balance plus $1,000/month at 6% for 10 years grows to roughly $195,000 — with contributions and compound growth both playing major roles.
Real-world uses
- Retirement planning: Model 401(k) or IRA growth with regular payroll contributions.
- Brokerage accounts: Estimate long-term returns on index fund or ETF portfolios.
- Goal setting: See how increasing monthly contributions accelerates reaching a target balance.
- Timing comparison: Compare beginning-of-period vs end-of-period contributions to quantify the difference.
Frequently Asked Questions
Returns compound at the frequency you select. Monthly contributions are added each month, and interest accrues on the growing balance. Beginning-of-period contributions earn interest for the full period; end-of-period contributions do not.
Historical U.S. stock market averages are often cited around 7–10% before inflation, but past performance does not guarantee future results. Conservative planners often use 5–7% for diversified portfolios.
Yes. Contributions at the beginning of each period start earning returns immediately, producing a slightly higher ending balance than end-of-period contributions over the same timeline.
No. This calculator shows pre-tax, pre-fee projections. Actual results depend on expense ratios, capital gains taxes, and account type (Roth vs traditional).