High-yield savings account calculator

What your result actually means

The headline figure is two piles of money stacked on top of each other. One pile is yours: the opening balance plus every monthly deposit. The other is what the bank paid you for keeping it there. Only the second pile is a return.

Take the default scenario. Start with $10,000, add $250 a month, earn 4.00% APY, and after five years you have $28,711.28. You deposited $25,000 of that. The bank contributed $3,711.28. That is a real gain for doing nothing, and it is also less dramatic than the phrase "compound interest" tends to suggest over a five-year window.

Stretch the same plan to twenty years and the split changes character. You would deposit $70,000 and finish with $112,871.66. Interest becomes $42,871.66, which is now a serious share of the total rather than a rounding difference. Compounding is not fast. It is patient.

What moves the number most

People usually arrive here wanting to know whether to chase a better rate. It is worth knowing how much that is actually worth relative to the other levers.

Rate shopping helps, but less than the marketing implies. Park $25,000 for five years at 4.20% and you finish with $30,709.91. At 3.75% you finish with $30,052.50. Chasing that 0.45 of a percentage point is worth $657.41 over five years, or about $11 a month. Worth an afternoon of paperwork, not worth checking rate tables every week.

Your monthly deposit does far more heavy lifting. In the default scenario, raising the monthly deposit from $250 to $350 adds roughly $6,600 over five years, which dwarfs anything a rate change can do at that balance. If you have a fixed amount of attention to spend, spend it on the deposit, not the bank.

Time is the lever nobody wants to hear about, because it cannot be sped up. It is also the only one that changes the shape of the curve rather than just its height. The bar chart above shows this directly: the darker band is interest, and it barely registers in year one before becoming the fastest-growing part of the stack.

Where a 4% rate comes from

The FDIC publishes a national average rate for savings accounts, and as of August 17, 2026 it sits at 0.38%. Most of that average comes from large branch banks that have no reason to compete on rate, because their customers do not move.

Online banks and credit unions compete on rate because it is the only thing they can compete on without branches. That is where the 3.75% to 4.20% range comes from. Nothing exotic is happening. The bank has lower overhead and passes some of it back to hold your deposit.

The gap between those two numbers is the entire argument for moving your money. On $10,000 left alone for a year, 4.00% pays $400 and the national average pays $38. Over ten years, the same $10,000 becomes $14,802.44 at 4.00% and $10,386.56 at 0.38%.

Why this calculator sometimes shows less than others

Run $10,000 at 4.00% APY for one year through this page and you get $10,400.00. Run it through several popular savings calculators and you get $10,407.42. Ours is the correct one, and the reason matters if you are comparing accounts.

APY is already an annual figure with compounding built into it. That is the entire point of the number and why federal disclosure rules require banks to publish it. A calculator that takes your 4.00% APY, divides it by twelve, and then compounds it monthly has applied compounding twice. The error is $7.42 in the first year on a $10,000 balance. Over thirty years it grows to $701.01.

To advance a balance by one month, this site multiplies by (1 + APY)^1/12 rather than adding APY divided by twelve. That inverts the compounding correctly, which is also why changing the compounding frequency here would not change your answer. The methodology page shows the full formula and the worked example.

What this calculator assumes

Every projection is a model, and it is only useful if you know where it bends away from reality. This one assumes four things.

It holds your APY steady for the whole term. No variable-rate savings account has ever done that. Treat a twenty-year projection as an illustration of how compounding behaves, not as a forecast of your balance in 2046.

It adds your monthly deposit at the end of each month, so a deposit earns nothing in the month it lands. Some banks are slightly more generous and start accruing the day the money clears. The difference is small and this choice keeps the estimate conservative.

It assumes you never withdraw, and that interest stays in the account rather than being swept somewhere else. It also ignores tax unless you enter a rate in the section above, which matters more than most people expect once the balance gets large.

Common questions about high-yield savings accounts

How much interest will $10,000 earn in a high-yield savings account?

At 4.00% APY, $10,000 earns exactly $400 over one year if you leave it alone. The first month pays about $32.74, and each month after that pays slightly more because the interest joins the balance. In an account paying the 0.38% national average, the same $10,000 earns $38 for the year.

Is a high-yield savings account worth it?

For cash you might need within a few years, yes. Moving $10,000 from an account paying the 0.38% national average to one paying 4.00% is worth $362 in the first year and $4,415 over ten years, with no extra risk as long as both banks are FDIC insured. For money you will not touch for decades, a savings account is the wrong tool because the rate barely outruns inflation.

How does compound interest work in a savings account?

The bank pays interest on your balance, then that interest becomes part of the balance and earns interest itself. Most banks calculate interest daily and pay it into the account once a month. The effect is small at first and grows the longer you leave the money alone. Over five years, $10,000 at 4.00% APY earns $2,166.53, against $2,000 if the interest never compounded. That $166.53 gap is compounding, and it widens every year after.

Is my money safe in a high-yield savings account?

If the bank is FDIC insured, your deposits are protected up to $250,000 per depositor, per insured bank, for each account ownership category. Credit unions carry equivalent NCUA coverage. Check that the institution is insured before you open the account, because some fintech apps route deposits through a partner bank and the coverage rules differ.

Do I pay taxes on high-yield savings interest?

Yes. The IRS treats savings interest as ordinary income in the year it is credited to your account, taxed at your marginal rate. Your bank sends Form 1099-INT if you earned $10 or more. In the 22% bracket, a five-year plan that earns $3,711 in interest costs about $805 in federal tax.

Can the bank lower my APY after I open the account?

Yes, and it will. Savings rates are variable and banks change them whenever they want, usually within weeks of a Federal Reserve move. A rate you open today is a snapshot, not a promise. If you need a rate locked for a fixed period, a CD does that instead.

How often does interest get paid into my account?

Almost always monthly, on a fixed statement date. Many banks accrue the interest daily and then credit the total once a month, which is why your balance jumps on the same day each month rather than creeping up. This calculator compounds monthly to match.

Does daily compounding beat monthly compounding?

Not when you are comparing APY figures. APY already includes the effect of compounding, whatever the frequency, which is exactly why banks are required to publish it. Two accounts advertising 4.00% APY pay the same amount over a year even if one compounds daily and the other monthly. Compare the APY and ignore the compounding schedule.

Sources

1. FDIC, National Rates and Rate Caps . National average savings rate of 0.38%, updated August 17, 2026
2. FDIC, Deposit Insurance . Coverage limits and ownership categories
3. IRS, Topic no. 403, Interest received . Interest is ordinary income and Form 1099-INT is issued at $10 or more
4. Consumer Financial Protection Bureau, savings account basics