Investment Growth Calculator: Compound Interest Over Time
Calculate how your investment grows over time using compound interest, with optional regular contributions.
Formulas Used
Future Value of Lump Sum (Compound Interest):
FVprincipal = P × (1 + r/n)n×t
Future Value of Regular Contributions (Annuity):
Effective rate per period: i = (1 + r/n)n/f − 1
FVcontributions = PMT × [((1 + i)f×t − 1) / i]
Total Future Value:
FVtotal = FVprincipal + FVcontributions
Where: P = principal, r = annual interest rate (decimal), n = compounding frequency per year, t = time in years, f = contribution frequency per year, PMT = regular contribution amount.
Assumptions & References
- Contributions are made at the end of each contribution period (ordinary annuity).
- The interest rate remains constant throughout the investment period.
- Compounding and contribution frequencies are independent and handled via effective rate conversion.
- No taxes, fees, or inflation adjustments are applied — results are nominal (pre-tax) values.
- Formula reference: Compound Interest — Investopedia; Time Value of Money — CFA Institute.
- For periods exceeding 50 years, the year-by-year table is truncated to 50 rows for readability.