AER Calculator - Annual Equivalent Rate Converter

The Annual Equivalent Rate calculator converts an advertised nominal interest rate into the effective rate produced after compounding. Banks and investment providers may quote the same nominal rate while crediting interest at different intervals. Because monthly, weekly, or daily credits begin earning interest themselves, their actual one-year returns differ. AER places those products on one annual basis, making savings accounts, certificates of deposit, money-market accounts, and other interest-bearing products easier to compare. The standard formula is AER = (1 + r ÷ n)^n - 1. In that expression, r is the nominal annual rate written as a decimal and n is the number of compounding periods in one year. Annual compounding uses one period, semi-annual uses two, quarterly uses four, monthly uses twelve, weekly uses fifty-two, and daily uses 365. The calculator converts the answer back to a percentage. It also compounds the effective annual rate over the entered investment term to estimate final value, interest earned, and total return. AER is usually slightly higher than the nominal rate unless interest compounds only once per year. The gap is small at low rates but grows as the interest rate or crediting frequency rises. For example, a 5% nominal rate compounded monthly has an AER above 5% because interest posted in the first month participates in every later month. The compounding increase in the result card isolates that difference in percentage points, while final amount shows its monetary effect on the entered principal. Use AER rather than nominal rates when products have different compounding schedules. It can also help evaluate a promotional savings offer, compare deposit ladders, or check an issuer’s effective-rate disclosure. Keep fees, taxes, introductory periods, withdrawal penalties, and changing rates in mind: two accounts with the same AER can still produce different net outcomes. For borrowing, a similar effective-rate calculation describes the cost of compounding, although regulated APR disclosures may follow jurisdiction-specific fee rules. The projection assumes the nominal rate, compounding frequency, and principal remain unchanged and that interest stays invested. It does not model added deposits, withdrawals, tax, account fees, or rate tiers. A bank may use 360-day conventions or compound continuously, so confirm the contract method when precision matters. AER is best treated as a standardized comparison metric and scenario estimate. Review the product disclosure before transferring funds or committing to a long-term deposit.