HYSA Interest Calculator
Calculate exactly how much interest you will earn in a high-yield savings account (HYSA) with daily compounding and optional monthly deposits. Compare APY rates and see the difference between a 0.05% big-bank account and a 4-5% online HYSA.
What Is a High-Yield Savings Account?
A high-yield savings account (HYSA) is an FDIC-insured savings account that pays significantly more interest than a traditional big-bank savings account. Where the national average savings rate is often around 0.4-0.6% APY, online banks and credit unions commonly pay 4-5% APY on liquid, no-minimum HYSAs. Interest is typically compounded daily and paid monthly. This calculator takes your starting balance, APY, time horizon, and monthly contributions, then projects your ending balance and total interest earned — so you can quantify the cost of leaving money in a low-rate account.
How HYSA Interest Is Calculated
Most HYSAs compound interest daily using the formula A = P(1 + r/n)^(nt), where P is principal, r is the annual rate as a decimal, n is compounding periods per year (365 for daily), and t is time in years. On a $10,000 balance at 4.5% APY with daily compounding, you earn roughly $460 in the first year — compared with about $5 in a 0.05% big-bank account. Adding monthly deposits multiplies the effect because each new deposit starts earning interest immediately on a compounding base.
APY vs APR — Why the Difference Matters
HYSAs advertise APY (annual percentage yield), which already factors in compounding. APR (annual percentage rate) is the simple interest rate before compounding. A 4.4% APR with daily compounding produces about 4.5% APY. When comparing accounts, always compare APY to APY — not APY to APR — or the higher-compounding account will appear worse than it is. This calculator asks for APY and does the daily-compound math internally, so your projection reflects what you will actually see at year-end.
HYSA vs CD vs Money Market
A HYSA keeps money fully liquid with no withdrawal penalty, which makes it ideal for emergency funds and short-term savings goals. A certificate of deposit (CD) locks money in for a fixed term (3 months to 5 years) in exchange for a slightly higher rate — but early withdrawal forfeits several months of interest. Money market accounts (MMAs) are similar to HYSAs but often include check-writing and debit access. For most savers, a HYSA is the right default because the rate gap versus CDs is usually small and flexibility is worth preserving.