How to use the high-yield savings calculator
Enter what is in the account today, how much you plan to add each month, the APY the bank offers and how long you will save. The result shows your ending balance, how much of it is interest, and how much more you earn than you would at the comparison rate. The yearly table shows the deposits and interest for each year, and you can open the month-by-month schedule to see every interest credit.
The comparison rate starts at 0.38%, the national average savings rate published by the FDIC (FDIC National Rates and Rate Caps, October 19, 2026). You can replace it with another bank's APY to compare two offers side by side.
What makes a savings account “high-yield”
There is no legal definition. Banks use the term for savings accounts that pay well above the national average, most often online banks and credit unions with lower costs than branch networks. The gap can be large: $10,000 left for a year earns $400.00 at 4.00% APY, compared with $38.00 at the 0.38% national average.
High-yield savings rates are variable. The bank can raise or lower the APY at any time, usually after changes in the Federal Reserve's interest rate target. That is the main difference from a certificate of deposit, which locks in a rate for a fixed term in exchange for a penalty if you withdraw early. Treat any long-term projection here as an estimate at today's rate.
The formula, with a worked example
Banks must quote savings accounts by annual percentage yield (APY) under the federal Truth in Savings rules (CFPB: Regulation DD (Truth in Savings)). The APY already includes compounding, so the calculator turns it into an effective monthly rate:
Monthly rate = (1 + APY)1/12 − 1, which is 0.3274% a month at 4.00% APY.
Balance after m months = P × (1 + i)m + D × ((1 + i)m − 1) ÷ i, where P is the starting balance, D the monthly deposit and i the monthly rate.
With $10,000 to start, $200 a month and 4.00% APY, you deposit $22,000.00 over 5 years and end with $25,402.33, so $3,402.33 is interest. At the 0.38% average you would have $22,304.04, which means the high-yield account earns you $3,098.29 more. Keep going for 10 years and the balance reaches $44,141.63, with $10,141.63 of interest, because interest is earned on earlier interest as well as on your deposits.
Because the APY includes compounding, daily or monthly compounding makes almost no difference to the result. What matters is the APY itself, how much you deposit and how long you leave it.
Using an HYSA for an emergency fund or a goal
A high-yield savings account suits money you may need at short notice, such as an emergency fund or savings for a car, a move or a down payment. Interest helps a little along the way. Starting with $2,000 and adding $500 a month at 4.00% APY, you reach $15,000 in 25 months, compared with 26 months with no interest at all. The bigger effect still comes from saving regularly, so set up an automatic transfer on payday.
For money you will not touch for several years, compare the rate with a fixed-rate CD in our CD calculator, or with tax-advantaged retirement accounts in the Roth IRA calculator and 401(k) calculator. To check whether your rate is beating rising prices, use the US inflation calculator.
Insurance, withdrawals and taxes
Deposits at FDIC-insured banks are covered up to $250,000 per depositor, per insured bank, for each account ownership category (FDIC deposit insurance). Federally insured credit unions offer the same $250,000 coverage through the NCUA (NCUA share insurance coverage). Some apps and fintechs are not banks themselves, so check which partner bank holds your money and that it is insured.
The Federal Reserve removed the old federal limit of six convenient withdrawals or transfers a month from savings accounts in April 2020 (Federal Reserve: Regulation D amendment (April 24, 2020)), but many banks still set their own limit or charge a fee for excess withdrawals. Check the account terms.
Savings interest is taxed as ordinary income in the year it is credited, and your bank sends Form 1099-INT if you earn $10 or more in a year (IRS Instructions for Form 1099-INT). The balances in this calculator are before tax.
Tips for choosing a high-yield savings account
Compare APYs. The APY is the fair way to compare accounts, because it already includes compounding.
Read the fine print. Look for monthly fees, minimum balances to earn the advertised rate, and introductory rates that drop after a few months.
Check transfer times. Moving money to your checking account at another bank can take one to three business days, so keep a small cushion in checking.
Revisit the rate. Because the APY is variable, check it every few months and move your money if your bank falls well behind other offers.
Updated October 25, 2026 · Sources are linked in the text above · How we build and check our calculators