How the Maturity Value Calculator works
This tool answers a simple question: if you deposit a lump sum today at a fixed interest rate, how much will it be worth when it matures? It uses the standard compound interest formula — the same math behind certificates of deposit (CDs), fixed deposits, and similar term-based savings instruments.
The formula
For a principal P, an annual interest rate r (as a decimal), a compounding frequency n (periods per year), and a term of t years, the maturity value is:
MV = P × (1 + r/n)n×t
Total interest earned is simply the maturity value minus the principal: Interest = MV − P. The calculator also reports the effective annual yield (APY), which converts the nominal rate and compounding frequency into a single true annualized return: APY = (1 + r/n)n − 1. This lets you compare deposits that compound at different frequencies on equal footing.
Worked example
Take a $10,000 deposit at a 5% annual rate, compounded monthly (n = 12), for a 5-year term. The formula gives (1 + 0.05/12)60 ≈ 1.28336, so the maturity value is about $12,833.59 — roughly $2,833.59 in interest on top of the original principal. The effective annual yield works out to about 5.12%, slightly above the nominal 5% rate because monthly compounding lets interest earn interest sooner than annual compounding would.
What moves the maturity value most
- Term length: because growth is exponential, extending the term has a larger effect the longer the deposit already runs — the last few years of a long term add more dollars than the first few.
- Interest rate: maturity value is highly sensitive to the rate, especially over longer terms, since the rate compounds on itself every period.
- Compounding frequency: moving from annual to monthly or daily compounding raises the maturity value, but the effect is modest compared to changes in rate or term — usually a fraction of a percentage point in effective yield.
What this calculator assumes
This model covers a single lump-sum deposit left untouched for the full term at one fixed rate — the way fixed deposits and CDs are typically quoted. It does not model recurring contributions, variable or tiered rates, taxes on interest income, or early-withdrawal penalties. If your account allows additional deposits or the rate can change, treat this result as a baseline rather than a final figure.