Interest accrues daily, but the bank pays it to you on a schedule

Interest on a savings account is calculated every single day based on your balance, but you don't receive that money immediately. Instead, the bank computes how much interest you've earned, then deposits it into your account on a set schedule — usually monthly, quarterly, or annually, depending on the bank. The amount you earn depends on three things: how much money sits in the account, the interest rate the bank offers, and how long the money stays there.

The daily calculation works like this: the bank takes your balance at the end of each day, multiplies it by the annual interest rate, and divides by 365. That gives you one day's worth of interest. The bank repeats this every day, adding up all those daily amounts. When the posting date arrives — say, the last day of the month — the bank deposits the total into your account at once.

Once interest is posted to your account, it becomes part of your balance. The next day, the bank starts calculating interest on that larger amount. This is called compounding, and it means you earn interest on your interest. The more often the bank compounds (daily, monthly, quarterly), the more you earn over time, even if the interest rate stays the same.

Key Takeaways

  • Interest is calculated on your account balance every day, but posted (added to your account) on a schedule set by your bank, usually monthly or quarterly.
  • The amount you earn each day depends on your balance, the annual interest rate, and the number of days in the year.
  • Once interest is posted, it becomes part of your balance and earns interest itself in the next compounding period.
  • Banks must disclose the Annual Percentage Yield (APY) on savings accounts, which already accounts for compounding and shows you the real annual return.

How the daily calculation actually works

To find out how much interest you earn in a single day, the bank uses this formula: (Your Balance × Annual Interest Rate) ÷ 365 = Daily Interest. If you have $10,000 in the account and the bank offers 4.50% APY, your daily interest is ($10,000 × 0.045) ÷ 365 = $1.23 per day. That's the amount the bank calculates for that one day only.

The bank does this calculation for every day of the month. If your balance stays at $10,000 for 30 days, you'd earn roughly $36.99 in interest that month (30 days × $1.23). But if you deposit an extra $5,000 on day 15, the calculation changes. Days 1–14 earn interest on $10,000, and days 15–30 earn interest on $15,000. The bank adds up all those daily amounts and posts the total when the month ends.

This is why the timing of deposits and withdrawals matters. Money you deposit early in the month earns interest for more days than money you deposit late in the month. Money you withdraw early stops earning interest immediately.

The difference between APR and APY

Banks are required to show you two numbers: the Annual Percentage Rate (APR) and the Annual Percentage Yield (APY). The APR is the raw interest rate — the percentage the bank pays on your balance. The APY is the real return you get after compounding is factored in.

Here's why they're different: if your bank compounds interest monthly, you earn interest on your interest 12 times a year. That compounds your money faster than if interest were paid just once at year's end. The APY number already includes this compounding effect, so it's always equal to or higher than the APR. If a bank advertises 4.50% APY, that's the actual yearly return you'll see, assuming your balance doesn't change.

When you're comparing savings accounts at different banks, always compare the APY, not the APR. Two banks might offer the same APR, but if one compounds daily and the other compounds quarterly, the daily-compounding bank will pay you more.

How often banks post interest to your account

The posting schedule varies by bank. Some post interest monthly (on the last day of the month or a set date), others quarterly (every three months), and a few post annually (once a year). A small number of online banks post interest daily, which means you see the money in your account every single day, though this is uncommon.

The posting schedule doesn't change how much interest you earn — the daily calculation happens regardless — but it does affect when you can see and use that money. If your bank posts monthly, you wait up to 30 days to see the interest added. If it posts quarterly, you wait up to 90 days. The bank's disclosure document (called the Truth in Savings Act disclosure) will tell you the exact posting frequency.

Some banks also offer different posting schedules for different account types. A high-yield savings account might post monthly, while a regular savings account posts quarterly. Check your account agreement or the bank's website to find out your specific posting date.

What happens if you withdraw money before interest posts

If you withdraw money before the posting date, you lose the interest that was calculated for those days. The bank only pays you interest on money that was actually in the account when the interest is posted. If you had $10,000 earning $1.23 per day, but you withdrew $5,000 on day 20 of a 30-day month, you'd lose interest on that $5,000 for days 20–30.

This is one reason people keep emergency funds in savings accounts separate from money they plan to spend soon. The longer money sits untouched, the more interest it earns. If you know you'll need the money within a month or two, the interest earned will be small anyway, so the timing of withdrawals matters less.

Some banks offer a grace period or a minimum balance requirement to earn interest at all. If your balance drops below the minimum, the bank might not pay any interest that month, or it might pay a lower rate. Read your account agreement to understand your bank's specific rules.

How interest rates change and what that means for you

The interest rate your bank offers is not fixed forever. Banks change their rates based on what the Federal Reserve does with its benchmark interest rate. When the Fed raises rates, banks typically raise savings account rates within days or weeks. When the Fed cuts rates, banks usually cut savings account rates just as quickly.

This means the APY you see today might be different next month. If rates are rising, your earnings will grow. If rates are falling, your earnings will shrink. The bank will notify you of any rate change, usually by email or through your online account portal, and the new rate takes effect on a date the bank specifies.

High-yield savings accounts tend to change rates more often than traditional savings accounts because they're designed to track market conditions closely. If you're earning 4.50% today, don't assume you'll earn that forever. Check your account statements regularly to see what rate you're currently earning.

Why your actual earnings might differ from the advertised rate

The APY you see advertised assumes your balance stays constant and you don't make deposits or withdrawals. In real life, most people's balances change. If you deposit money partway through the month, your average balance is lower than it would be if you'd deposited it on day one, so you earn less interest. If you withdraw money, the same principle applies.

Some banks calculate interest based on your average daily balance (the total of all daily balances divided by the number of days), while others use your ending balance (what you have on the last day of the month). The method matters. If you deposit $5,000 on the last day of the month, a bank using ending balance will pay you interest on that full $5,000 starting next month. A bank using average daily balance will pay you less, because your average balance for the month was lower.

Your account agreement will specify which method your bank uses. This is another reason to compare not just the APY, but also the compounding frequency and balance calculation method when choosing a savings account.

Frequently Asked Questions

Can I earn interest on interest before the posting date?

No. Interest is calculated daily, but it doesn't become part of your balance until the posting date. Until then, it exists only in the bank's records. Once it's posted, it becomes real money in your account and earns interest in the next compounding period.

What if my bank posts interest quarterly instead of monthly — do I earn less?

You earn the same total amount over the year, but you have to wait longer to see it. The daily calculation is the same; the only difference is when the bank adds it to your account. Quarterly posting means you wait up to 90 days instead of 30, but the annual total is identical.

Does a higher APY always mean I'll earn more money?

Yes, if your balance stays the same. A 5.00% APY will always earn you more than a 4.50% APY on the same balance. But if you're comparing accounts with different compounding frequencies or balance calculation methods, read the fine print to make sure you're comparing apples to apples.

What happens to my interest if I close the account before the posting date?

Most banks will pay you the interest that was earned up to the day you close the account, even if it hasn't been posted yet. The bank calculates what you're owed and includes it in your final balance. Check with your bank to confirm their specific policy.

Can I move my money to earn interest faster?

No. Interest accrues at the same daily rate regardless of where your money sits. Moving it between accounts doesn't speed up the process. The only way to earn more interest is to have a larger balance, a higher interest rate, or to let the money sit longer so compounding has more time to work.