How to use
- Start from the sample deposit, rate, and years; adjust to match your account.
- Pick a compounding frequency that mirrors your bank or credit union.
- Results refresh as you type; use "Copy URL" to save or share this scenario.
Calculated in your browser only; nothing is sent to a server.
How it’s calculated
1) Definitions
- P = today’s deposit (principal); r = annual rate (%); m = times interest is added per year; t = years
2) Assumptions
- Inputs must be positive numbers
3) Formulae
- FV = P × (1 + r/m)m×t
- EAR = (1 + r/m)m − 1
- Interest = FV − P
4) Example
P=$10,000, r=8%, m=12, t=1 → FV ≈ $10,830; interest ≈ $830.
FAQ
What do P, r, m, and t mean?
P is the money you deposit now (principal). r is the annual interest rate in percent. m is how many times interest is added in a year (12 monthly, 4 quarterly, 1 yearly). t is the time in years you keep the deposit.
What is the effective annual rate (EAR)?
EAR is the true yearly growth after compounding: EAR = (1 + r/m)m − 1. It lets you compare accounts with different compounding schedules.
Which compounding option should I pick?
Choose the same schedule your bank uses. Savings accounts are often monthly, some CDs are quarterly, and simple term deposits may be yearly. If your account compounds daily, monthly is a close approximation.
What should I do first on this page?
Start with the minimum required inputs or the first action shown near the primary button. Keep optional settings at defaults for a baseline run, then change one setting at a time so you can explain what caused each output change.
Why does this page differ from another tool?
Different pages often use different defaults, units, rounding rules, or assumptions. Align those settings before comparing outputs. If differences remain, compare each intermediate step rather than only the final number.