Savings and investing guide
APY vs. Interest Rate: How to Compare Savings Accounts
The interest rate describes the rate used to calculate interest on a deposit. Annual percentage yield (APY) reflects both that rate and compounding over a year. When comparing deposit accounts, APY is a useful disclosed measure, but fees, rate changes, balance requirements, and access rules still matter.
What the two rates mean
A deposit account’s stated interest rate is the rate applied under its terms. APY expresses the annual yield after accounting for how often interest compounds, assuming the balance and rate meet the disclosure assumptions. For the same nominal rate and a positive balance, more frequent compounding can produce a higher annual yield. A variable account can still change its rate after you open it.
The basic APY formula
For a constant nominal annual rate r compounded m times per year, a simplified formula is APY = (1 + r/m)^m − 1. Use rates as decimals: 4.8% becomes 0.048. This formula assumes the rate stays constant, interest remains in the account, there are no fees or withdrawals, and the period is a standard year. Banks calculate and disclose APY under applicable account-disclosure rules, which may use more specific day-count assumptions.
A hypothetical $1,000 example
Suppose an account has a 4.8% nominal annual rate compounded monthly for a year. The simplified formula gives (1 + 0.048/12)^12 − 1, or about 4.91% APY. On $1,000 kept in the account for that year, that is about $49.07 in interest before fees and taxes. This is a math illustration, not a current rate offer or a prediction of what a variable-rate account will pay.
How to compare real accounts
Compare APYs for the same date and similar account types, then read the disclosures. Check whether the rate is introductory or variable, the minimum balance needed to earn it, monthly maintenance fees, withdrawal limits, and any minimum opening deposit. A slightly higher APY can be outweighed by fees or requirements you cannot consistently meet. Confirm whether the account is held at an FDIC-insured bank and understand which institution holds the deposit.
APY is not an investment return forecast
APY is used for deposit accounts and reflects stated account terms. It does not establish that an investment will earn that return. Market investments can lose value, and projected returns are uncertain. A calculator can show how a balance might grow under a fixed-rate assumption, but it cannot guarantee the rate will remain available or account for every fee, tax, or withdrawal rule.
Read the balance and rate conditions
Some accounts offer a stated APY only above a minimum balance, in one balance tier, or for a limited introductory period. A fee can reduce the dollars you keep even when the quoted APY is accurate. Check whether the rate is variable and when the bank may change it. If you compare accounts on different dates, record the date because a published APY is not a permanent rate commitment.
A useful comparison worksheet
For each account, record the APY, whether it is fixed or variable, the minimum balance, opening deposit, maintenance fee, access conditions, and the institution holding the funds. Then compare the dollar result on the balance you actually plan to keep, not just the largest advertised percentage. The compound-interest calculator is useful for a fixed-rate scenario, while the account disclosure determines the actual product terms.
Frequently asked questions
Is APY the same as APR?
No. APY is a deposit-account yield that reflects compounding. APR is commonly used to disclose borrowing costs under applicable rules; compare the definitions and product terms rather than treating them as interchangeable.
Can a savings APY change?
Yes, a variable-rate account may change its rate. Check the account disclosures and current rate.
Sources and further reading
Try the calculator
Use the Compound Interest Calculator to explore your own numbers with the assumptions shown in the tool.
Related guides
Educational content only; not individualized financial, tax, or legal advice.