About the Investment Calculator

What it does

Estimates future value of your money using compound growth. Supports a starting amount, recurring contributions, an annual return rate, compounding, time horizon, and optional inflation or taxes.

Key concepts

• Simple vs. compound growth: Compound growth reinvests earnings, creating growth on growth.
• Compounding frequency: Annual, quarterly, monthly, or daily. More frequent compounding yields slightly more.
• Nominal vs. real return: Real return ≈ nominal return − inflation.

Fields in this calculator

• Initial investment: Lump sum you invest at the start.
• Recurring contribution: Deposit added each period (e.g., monthly).
• Annual return (%): Expected average yearly rate before fees/tax.
• Compounding: How often earnings are compounded (annual/quarterly/monthly/daily).
• Years: Time horizon of the plan.
• Inflation (%) (optional): Used to show results in today’s money.
• Tax on gains (%) (optional): Simple approximation of taxes on investment returns.

Formulas

Let:
  P  = initial investment
  C  = contribution per period
  r  = annual rate (decimal)
  m  = compounding periods per year
  n  = years × m
  i  = r / m

Future value of P:        FV_P = P × (1 + i)^n
Future value of C series: FV_C = C × [((1 + i)^n - 1) / i]
Total future value:       FV   = FV_P + FV_C

Real FV (inflation j):    i_real ≈ ((1+r)/(1+j) - 1)/m ; use i_real in place of i