A savings account rewards two habits: putting money in regularly and leaving it alone. This calculator models both. Enter an opening deposit, a recurring deposit, the account’s rate and a time frame, and it builds the balance one deposit period at a time — so you can see exactly how much of the ending figure is money you added and how much the bank paid you.
How to use the savings calculator
- Enter your initial deposit — the amount already in the account or the amount you will open it with.
- Enter the regular deposit and how often you make it (weekly, every two weeks, monthly and so on).
- Choose whether deposits land at the end of each period (typical for automatic transfers after payday) or the beginning.
- Enter the interest rate and say whether it is an APY or a nominal APR. If you pick APR, also choose the compounding frequency.
- Enter the number of years, and optionally a yearly raise to your deposits if you plan to save more as your income grows.
The result shows the ending balance, total deposits, total interest, a stacked chart of deposits versus interest, and a year-by-year table.
How the balance is calculated
The calculator converts the yearly rate into a rate per deposit period, then applies it period by period:
where p is the number of deposits per year. With level deposits D, an opening balance B and n periods, the closed-form version is:
Deposits made at the start of each period are multiplied by one more factor of (1 + r). When you add a yearly raise, each year’s deposits are compounded separately, which the table shows row by row.
Worked example
You open a high-yield savings account with $5,000, add $200 at the end of every month, and earn 4% APY for 10 years.
- Monthly rate: 1.041/12 − 1 = 0.327374%
- The opening $5,000 grows to $5,000 × 1.0410 = $7,401.22
- The 120 deposits grow to $200 × (1.0410 − 1) ÷ 0.00327374 = $29,339.18
- Ending balance: $36,740.41, of which $29,000 is your money and $7,740.41 is interest
What moves the ending balance most
Starting from the example above, here is what changes when you adjust one input at a time:
| Change | Ending balance | Interest earned |
|---|---|---|
| None (baseline) | $36,740.41 | $7,740.41 |
| Rate 5% APY instead of 4% | $39,017.11 | $10,017.11 |
| Deposit $300 instead of $200 | $51,410.00 | $10,410.00 |
| Save for 15 years instead of 10 | $57,936.13 | $16,936.13 |
| Raise deposits 3% each year | $40,715.51 | $8,202.20 |
| Deposit at the start of each month | $36,836.46 | $7,836.46 |
The pattern is typical for savings: over a decade, the size of your deposits matters more than a one-point difference in rate. Time is the multiplier that eventually makes interest a meaningful share of the balance.
APY, APR and compounding
APR is the nominal yearly rate before compounding; APY is the yield you actually earn after a year of compounding. A 4% APR compounded daily works out to about 4.081% APY, while a 4% APY is simply 4% for the year. Because the Truth in Savings Act requires banks to quote APY, comparing accounts by APY is the cleanest apples-to-apples test, and it is the default here.
Keeping savings safe and realistic
Deposits at FDIC-insured banks (and NCUA-insured credit unions) are protected up to $250,000 per depositor, per institution, per ownership category. Online banks often pay noticeably more than traditional branches for the same protection. Remember that savings rates float with the market, and that inflation erodes buying power — the inflation calculator shows how much. For a fixed rate locked in for a set term, compare against a CD; to work backward from a target amount, use the savings goal calculator.
Results are estimates for planning only and are not financial advice. Actual interest depends on your bank's rate changes, crediting schedule and fees.
Frequently asked questions
Should I enter APY or APR?
Enter whatever your bank quotes and pick the matching option. US banks must disclose APY on deposit accounts under the Truth in Savings Act, and APY already includes the effect of compounding, so you do not need to choose a compounding frequency when you enter it.
Does it matter whether I deposit at the start or end of the month?
A little. A deposit made at the start of a period earns one extra period of interest. Over 10 years with $200 a month at 4% APY, depositing at the start of each month instead of the end adds about $96.
Is savings account interest taxed?
Yes. In the US, interest from savings accounts, money market accounts and CDs is taxed as ordinary income in the year it is credited, and banks report it on Form 1099-INT once it reaches $10. The calculator shows pre-tax growth.
Why is my bank balance different from the calculator?
Savings rates are variable and can change at any time, banks credit interest on specific dates, and some accounts have tiered rates or fees. The calculator assumes one steady rate, so treat the result as a projection rather than a statement.
How much of my balance will be interest?
Over short periods, very little — most of the balance is your own deposits. The interest share grows with time and rate: $5,000 plus $200 a month at 4% APY is about 21% interest after 10 years and about 29% after 15.