What this calculator does
See how much your savings could grow to over the years. A savings account grows in two ways: the money you add, and the interest the bank pays on what's already there. This calculator uses the rate your bank advertises, called the APY. It shows what a starting deposit plus a steady saving habit can add up to.
You can save weekly, every two weeks (handy if you save from each paycheck), monthly or yearly. You can also raise your deposits a little each year as your income grows. Optional boxes take out tax on the interest and show the final balance in today's dollars. You'll see the final balance, how much of it you put in, how much is interest, and a year-by-year table and chart.
Where it's used
Why this math matters outside the classroom:
- Regular deposits. Depositing $200 a month for 5 years at a 4% APY grows to about $13,235.80.
- Deposit frequency. Savers compare weekly, biweekly and monthly deposits of the same yearly total to see how timing changes growth.
- After tax and inflation. Subtracting tax on interest and adjusting for inflation shows what a balance could buy in today's dollars.
- Stepping up deposits. Raising the deposit a little each year shows how growing contributions add to the final balance.
Grade level and standards: Grades 11–12; Common Core State Standards for Mathematics HSA.SSE.B.4, HSA.SSE.B.3.c. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Enter what you're starting with and how much you plan to add each time. Then choose how often you save, and whether each deposit goes in at the start or the end of the period.
- Enter the APY from your bank or account offer, and the number of years. Part years are rounded to the nearest whole deposit.
- If you like, raise your deposits by a percent each year. You can also enter a tax rate on interest, or an inflation rate to see the result in today's money.
- Read the final balance and how it splits between your deposits and interest. Then scroll the table to watch the balance build year by year.
What the inputs mean
- Deposit every
- How often you add money. The calculator turns the APY into a matching rate for each period. So changing this only changes when your deposits arrive, not what you earn in a year.
- Deposits are made at the
- A deposit at the start of a period earns interest for that period. One at the end starts earning in the next period.
- Annual percentage yield (APY)
- APY (annual percentage yield) is what you earn in a year, including interest on your interest. That interest on interest is called compounding. US banks must advertise savings accounts this way. Since compounding is already built into the APY, there's no separate setting for it: a full year always grows by exactly the APY.
- Raise deposits each year by
- How much to raise your deposit each year, for example 3% to keep up with pay raises. The raise starts at the beginning of each new year.
- Tax rate on interest
- Interest in an ordinary savings account is usually taxed as income each year. Enter your marginal rate (the tax rate on your last dollars of income) to see the after-tax result. Leave it blank for an account where interest isn't taxed along the way.
- Inflation
- How much you expect prices to rise each year, on average. The calculator uses it to show what your final balance would buy in today's money.
Formula and method
rate per period: i = (1 + APY)^(1 ÷ p) − 1 after tax: i′ = i × (1 − tax rate) number of periods: n = years × p starting deposit: P × (1 + i′)^n deposits at end of period: D × ((1 + i′)^n − 1) ÷ i′ deposits at start of period: D × ((1 + i′)^n − 1) ÷ i′ × (1 + i′) today's dollars = balance ÷ (1 + inflation)^years
In the formulas, P is your starting deposit, D is each regular deposit, and p is how many deposits you make in a year. That's 52 for weekly, 26 for every two weeks, 12 for monthly and 1 for yearly. The rate i is what you earn in each period, i′ is that rate after tax, and n is the total number of deposits.
The first formula turns the APY into a rate for each period. Done this way, 12 monthly interest payments, or 52 weekly ones, add up to exactly the advertised APY over a year.
Your balance is your starting deposit after it grows, plus all your regular deposits after they grow. If your deposits rise each year, there's no single shortcut formula. So the calculator adds interest and deposits one period at a time instead, and the yearly table shows that running total.
Interest is the final balance minus everything you put in. If you enter a tax rate, the tax on each interest payment is taken out before it can earn more interest. That comes very close to paying tax on your interest once a year.
Worked example
You open a high-yield account with $5,000. You add $300 at the end of every month and earn 4% APY for 10 years, without raising your deposits.
- Monthly rate: 1.04^(1/12) − 1 ≈ 0.00327374, or about 0.3274% a month.
- Starting deposit: $5,000 × 1.04^10 ≈ $7,401.22.
- Monthly deposits: 120 deposits of $300 grow to about $44,008.78.
- Final balance: $7,401.22 + $44,008.78 = $51,410.00.
- You put in $5,000 + 120 × $300 = $41,000.
Result: After 10 years the account holds about $51,410.00. About $10,410.00 of that is interest.
Understanding the result
The interest figure shows how hard your money is working. At first, nearly the whole balance is your own deposits. In the chart, the gap between the balance line and the deposits line grows each year as your interest starts earning interest too.
If you entered inflation, compare the today's-dollars figure with your total deposits. An account that earns less than inflation keeps your money safe and easy to reach. But it slowly loses buying power. That's why cash savings suit short-term goals and emergency funds better than long-term growth.
Assumptions and limitations
- The APY stays the same the whole time. In real life, savings and money market rates can change at any time.
- You make every deposit on schedule and take nothing out.
- Interest is paid each time you deposit, at the rate that matches the APY. Banks may pay it daily or monthly instead, which gives the same growth over a year.
- If you enter a tax rate, it's a flat rate taken from interest as you earn it. Fees aren't included.
- This is an estimate to help you plan. It isn't financial advice or a quote from any bank.
- Banks round each interest payment to the cent and may count days differently. So your real statements can differ by small amounts.
- It doesn't cover deposit insurance limits, minimum balance rules, promotional rates or limits on withdrawals.
Frequently asked questions
How is this different from the compound interest calculator?
The compound interest calculator starts from a stated interest rate, before compounding, and lets you choose how often interest is added. This one starts from the APY, the figure savings accounts actually advertise. It also adds savings features: weekly or every-two-weeks deposits, yearly raises, tax on interest and a today's-dollars view.
Should I enter the APY or the interest rate?
Enter the APY. The interest rate (sometimes shown as APR) is the rate before compounding. The APY is what you actually earn in a year. If you only know the interest rate, the APY calculator can convert it for you.
Do weekly deposits earn more than monthly ones?
Only a little, and mostly because your money goes in sooner. $300 a month and $69.23 a week add up to nearly the same amount each year, and the balances end up close. Saving more in total matters far more than how often you save.
Is interest on savings taxable?
In the US, interest from ordinary savings accounts is generally taxed as income in the year it's paid. Some retirement and education accounts delay that tax or skip it entirely. Enter your tax rate to estimate your after-tax balance, and check your own situation with a tax professional.
How much should I keep in savings?
It depends on your costs and goals. Many people start with an emergency fund that covers a few months of essential bills. Then they save toward specific goals. The emergency fund and savings goal calculators can help you size those targets.
How this calculator is checked
Method: Effective-rate conversion i = (1 + APY)^(1/p) − 1; future value of a lump sum and of an ordinary annuity or annuity due; period-by-period recursion when deposits step up yearly. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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