🏦 Effective Interest Rate
Convert APR to effective APY for any compounding period, then compare bank deposit terms in real money: interest at maturity, monthly or upfront.
Compare deposit terms (rolled over for a full 12 months)
Effective rate: APY = (1 + r/m)^m − 1; continuous: e^r − 1. A k-month deposit at r%/yr with interest d = r·k/12 per term: paid at maturity and rolled over, APY = (1 + d)^(12/k) − 1; paid monthly (not compounded), APY = r; paid upfront, you receive d the day you deposit and redeposit principal plus that interest at the next term, so the 12-month total also equals (1 + d)^(12/k), only paid earlier. Banks quote a lower upfront rate than the at-maturity rate; always enter the rate quoted for the payout type you pick. Terms that do not divide 12 (9, 13, 18, 24 months) show an annualised figure: the deposit has not matured at month 12 and early withdrawal only earns the demand-deposit rate. Interest uses equal months (k/12 of a year), while banks accrue on actual days over a 365-day year (Circular 14/2017/TT-NHNN), so statement figures differ by a few thousand đồng.