Model real bank savings-account mechanics - APY vs nominal rate, tiered rates, promotional rates, fees - and compare up to 6 banks side by side.
Recent Calculations
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Rate
Assumption: in APY mode the day-to-day simulation basis is daily compounding (the most common real bank practice). In Nominal mode, the simulation uses the compounding frequency you select.
Optional Features
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The first-tier rate (your APY/nominal rate above) applies to the balance up to the threshold; the second-tier APY applies to the portion above it. Recalculated every period as the balance grows.
The promo APY applies for the first N months, then the account reverts to the regular (or tiered) rate for the rest of the term.
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If the balance is at/above the minimum, no fee applies that month. If below, the fee is deducted from the balance FIRST, then interest is calculated on the post-fee balance (the more conservative/realistic ordering).
Export Details
Optional - blank fields are omitted from the export. Nothing is sent anywhere; all fields stay in your browser.
Final Balance
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Total Contributions
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Total Interest Earned
$0.00
Total Fees Paid
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Effective APY Used
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Growth Chart (Principal + Contributions vs Interest)
Accumulation Schedule (Annual)
Year
Contributions
Interest
Fees
Ending Balance
Rates shown are illustrative and can change at any time at the bank's discretion. FDIC insurance covers up to $250,000 per depositor, per insured bank, per ownership category - balances approaching or exceeding this limit may not be fully insured. Promotional rates expire and revert to the standard rate as modeled above. This calculator is for illustrative purposes only and does not constitute financial advice.
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Same deposit, contribution and term are applied to every bank below so the comparison is apples-to-apples - only each bank's rate/fee/tier/promo terms differ.
You've reached the maximum of 6 banks for this comparison.
Final Balance by Bank
Comparison Table
Bank
Effective APY
Final Balance
Total Interest
Total Fees
Net Interest After Fees
Optional - blank fields are omitted from the export.
Rates shown are illustrative and can change at any time at each bank's discretion. FDIC insurance covers up to $250,000 per depositor, per insured bank, per ownership category. Promotional rates expire and revert to the standard rate as modeled above. This calculator is for illustrative purposes only and does not constitute financial advice.
The APY printed on a savings account’s homepage rarely tells the whole story, promotional rates expire, tiered rates only apply above certain balances, and monthly fees can quietly erode your growth. This calculator models all of that together and lets you compare up to six banks side by side using the exact same deposit, contribution, and term.
How to use this savings account interest calculator
Enter your Initial Deposit, Monthly Contribution, APY, and savings Term.
If your account offers a promotional rate, enable it and enter the Promo APY and how many months it lasts.
If your account charges a monthly maintenance fee, enable it and set the fee amount and minimum balance to waive it.
Review your Final Balance, Total Interest Earned, Total Fees Paid, and Effective APY Used.
Switch to the Compare Banks tab to test the same deposit and contribution across several banks at once.
What this savings account interest calculator does
Beyond a simple compound-interest projection, this calculator layers in the real-world mechanics that determine what you’ll actually earn: promotional rates that step down to a standard rate after an introductory period, and monthly fees that are waived above a minimum balance threshold but otherwise deducted before interest is calculated for that month.
How promotional rates are modeled
Many savings accounts advertise an attractive APY that only applies for an introductory period, commonly 3 to 12 months, after which the rate reverts to a lower standard (or tiered) rate for the remainder of the term. This calculator applies your Promo APY for the number of months you specify, then automatically switches to the regular rate afterward, so the Final Balance reflects the blended reality rather than the promotional headline rate.
How the fee-waiver ordering works
If your balance falls below the minimum required to waive the monthly fee, this calculator deducts the fee from your balance first, then calculates that month’s interest on the resulting post-fee balance. This is the more conservative and realistic ordering, since it mirrors how most banks actually apply fees before crediting interest, rather than assuming you’d earn interest on funds that are about to be deducted.
Effective APY Used = blended rate across promo period + standard/tiered period, after fees
Ending Balance = Prior Balance + Contributions + Interest − Fees (if below minimum balance)
Why the bank comparison tab uses identical inputs
The Compare Banks tab deliberately applies the same initial deposit, monthly contribution, and term across every bank you add, varying only each bank’s rate, fee, tier, and promo terms. This apples-to-apples structure isolates exactly how much of the final balance difference comes from the account terms themselves, rather than from inconsistent assumptions about how much you’re saving.
A note on FDIC insurance
FDIC insurance (US) covers up to $250,000 per depositor, per insured bank, per ownership category. If your projected balance approaches or exceeds this limit at a single bank, part of it may not be fully insured, worth keeping in mind when comparing a high-yield account against spreading savings across multiple insured institutions.
Frequently asked questions
Why is my Effective APY Used different from the rate I entered?
If you enabled a promotional rate, the Effective APY Used blends the higher promo rate during its introductory period with the lower standard or tiered rate for the rest of the term, which will differ from either individual rate on its own.
How are monthly fees applied if my balance drops below the minimum?
The fee is deducted from your balance first, and interest for that month is then calculated on the reduced, post-fee balance. This is the more conservative ordering and mirrors how most banks actually process fees and interest.
Is my full balance always FDIC insured?
FDIC insurance covers up to $250,000 per depositor, per insured bank, per ownership category. Balances approaching or exceeding that limit at a single institution may not be fully covered.
