Algebra 2 Intermediate

Compound Interest

Calculate future value with periodic or continuous compounding using exponential growth formulas.

Live Calculator · Step-by-Step · Algebra 2
Compounding Setup
A = 1000(1 + 0.05/12)^(12·5)
Uses A = P(1 + r/n)^(nt). Enter rate as a percentage (e.g., 5 for 5%).
Examples — effect of compounding frequency
A = 1000·e^(0.05·5)
Uses A = Pe^(rt). Continuous compounding — the theoretical maximum for a given rate.
Examples
Result
Enter values above and press Calculate to see the future value, interest earned, and APY.
Future Value A
Interest Earned
Effective APY
Periodic vs Continuous
Step-by-Step Solution
Growth Curve
—— Periodic   —— Continuous   Computed point   Principal
Formula Variables
A = P(1 + r/n)^(nt)
VariableMeaning
PPrincipal — initial amount invested or borrowed
rAnnual interest rate as a decimal (e.g. 5% → 0.05)
nNumber of times interest compounds per year
tTime in years
AFinal amount (principal + interest)

Common n values:

Annually = 1  ·  Semi-annually = 2  ·  Quarterly = 4  ·  Monthly = 12  ·  Daily = 365

The effective APY (annual percentage yield) accounts for compounding and is always slightly higher than the nominal rate r:

APY = (1 + r/n)^n − 1

Always convert the percentage rate to decimal form before plugging into the formula: r = given% ÷ 100.
Continuous vs Periodic
A = Peʳᵗ   (continuous)

As n → ∞, the periodic formula (1 + r/n)^(nt) approaches the natural exponential e^(rt). This is the mathematical limit of compounding more and more frequently.

Continuous compounding always gives a slightly higher return than any finite n, but the difference shrinks as n grows larger.

For 5% annually over 5 years with $1,000:

Monthly (n=12): $1,283.36

Daily (n=365): $1,284.00

Continuous: $1,284.03

  • Continuous compounding is used in many finance and calculus models.
  • In practice, banks use daily or monthly compounding.
  • The difference between daily and continuous is negligibly small.
  • APY is the fair comparison number across different compounding methods.

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