Compound interest calculator

Client

Estimate how a lump sum grows with a fixed nominal annual rate and a chosen compounding schedule—useful for savings, CDs, and simple projections (not tax or fee advice).

Compound interest inputs

%
?
Nominal annual rate (APR-style) with compound periods per year. For savings or CDs; not a loan payoff—see the loan payment calculator for amortization.

Future value: $16470.09

Interest earned: $6470.09

Effective annual rate (APY): 5.1162%

Common use cases

  • Estimate future value of a lump sum given APR and compounding frequency.
  • Compare nominal APR with effective APY when products quote different rates.
  • Model simple savings growth before adding fees, taxes, or contributions.

Common mistakes to avoid

  • Confusing nominal APR with compounding frequency

    More frequent compounding increases yield at the same nominal rate—compare APY when shopping products.

  • Treating projections as guaranteed returns

    Market and bank products change; this is educational math, not investment advice.

FAQ

Are compound calculations done locally?

Yes. Numbers never leave your browser tab.

Does this include monthly contributions?

It models a single principal with compounding. Add contributions manually or use a spreadsheet for annuity-style schedules.

More tools

Related utilities you can open in another tab—mostly client-side.