Quick answer: With a $10,000 initial deposit plus $500 a month at 4% APY compounded monthly for 10 years, you would have about $88,533: $70,000 of your own contributions and $18,533 in interest. Enter your own numbers above to see your projection instantly.
Last reviewed: October 2026
Key facts
- Compound interest means you earn interest on your interest, so growth accelerates over time.
- APY (annual percentage yield) already includes the effect of compounding; APR usually does not.
- More frequent compounding (daily vs annual) grows a balance slightly faster at the same nominal rate.
- Bank deposits in the US are FDIC-insured up to $250,000 per depositor, per insured bank.
A savings calculator projects how your deposits grow with compound interest. Enter an initial deposit, a monthly contribution, the APY, the number of years, and the compounding frequency to see your future value, total contributions, and interest earned.
Most people save without knowing what their money will actually become. A savings calculator turns a vague habit into a concrete projection: it shows how much of your future balance comes from your own deposits and how much comes from interest doing the quiet work in the background. That split is motivating, because once compounding takes over, your money starts earning on its own. This free tool gives you that projection in seconds, with no signup.
How to use this savings calculator
- Enter your initial deposit: the lump sum you are starting with (enter 0 if you are starting from scratch).
- Enter your monthly contribution: the amount you plan to add every month.
- Enter the APY: the annual percentage yield your account pays.
- Enter the number of years you plan to keep saving.
- Choose the compounding frequency: daily, monthly, quarterly, or annually.
- Click Calculate to see your future value, total contributions, and interest earned.
Savings calculator formula
The formula has two parts. The first part grows your initial deposit P at the periodic rate r/n for nt periods. The second part grows your stream of monthly contributions PMT, where each deposit compounds for the time remaining after it lands. The calculator assumes contributions arrive at the end of each compounding period. Total contributions are simply P + (PMT × n × t), and interest earned is the future value minus total contributions.
How the savings calculator handles compounding frequency
Compounding frequency is how often the bank adds interest to your balance. Daily compounding credits interest every day, monthly adds it once a month, and annual compounding adds it once a year. With a nominal rate of 4% on $10,000 over 10 years, the differences are real but modest:
| Compounding | Future value of $10,000 | Extra vs annual |
|---|---|---|
| Annual | $14,802.44 | - |
| Quarterly | $14,888.64 | $86.20 |
| Monthly | $14,908.33 | $105.89 |
| Daily | $14,917.92 | $115.48 |
Frequency matters far less than the rate itself and the amount you contribute. Moving from a 1% account to a 4% high-yield account changes your outcome by thousands; moving from monthly to daily compounding changes it by tens of dollars on a $10,000 balance.
Worked examples
Example 1: $10,000 start, $500 a month, 4% APY, 10 years
Monthly rate r/n = 0.04/12 = 0.003333, periods nt = 120. Growth factor (1.003333)120 = 1.49083. Initial deposit part: $10,000 × 1.49083 = $14,908.33. Contribution part: $500 × (1.49083 - 1)/0.003333 = $500 × 147.25 = $73,624.90. Future value = $88,533.23. Total contributions = $10,000 + ($500 × 120) = $70,000. Interest earned = $88,533.23 - $70,000 = $18,533.23.
Example 2: starting from zero, $200 a month, 3% APY, 5 years
Monthly rate = 0.03/12 = 0.0025, periods = 60. Growth factor (1.0025)60 = 1.16162. Contribution part: $200 × (1.16162 - 1)/0.0025 = $200 × 64.65 = $12,929.34. Future value = $12,929.34. Total contributions = $200 × 60 = $12,000. Interest earned = $12,929.34 - $12,000 = $929.34. Even five years of steady $200 deposits earns nearly a thousand dollars in interest at a modest rate.
Tips for growing your savings faster
- Start early, even with small amounts. Time does more work than extra dollars: Example 2 shows $200 a month growing to nearly $13,000 in five years.
- Compare APYs, not APRs. APY already includes compounding, so a 4.00% APY beats a 4.00% APR compounded monthly.
- Automate the transfer. A monthly transfer on payday removes the decision and keeps contributions consistent, which is what the formula assumes.
- Consider high-yield savings accounts. Online banks typically pay far more than traditional brick-and-mortar accounts, and the money stays FDIC-insured.
- Revisit the rate yearly. Savings rates move with the economy; a rate that was competitive last year may lag today.
Common mistakes to avoid
- Confusing APY with APR. If your bank quotes an APR, the true yearly growth (APY) is slightly higher when interest compounds more than once a year.
- Ignoring taxes on interest. The IRS taxes savings interest as ordinary income, so your after-tax growth is lower than the headline APY.
- Assuming the rate stays fixed. Savings APYs are variable: banks can raise or lower them at any time, so long projections are estimates.
- Forgetting fees. Monthly maintenance fees on low-balance accounts can erase interest entirely; the calculator assumes no fees.
- Stopping contributions. The projections assume every monthly deposit lands on time. Skipped months shrink the result more than most people expect.
Frequently asked questions
What is APY on a savings account?
APY stands for annual percentage yield. It is the yearly return on your savings including the effect of compounding, so it tells you exactly how much $100 grows in one year. A 4% APY turns $100 into $104 after a year, before taxes.
How often is savings account interest compounded?
Most US savings accounts compound daily or monthly and credit the interest monthly. Daily compounding grows a balance slightly faster than monthly at the same nominal rate. The calculator lets you pick daily, monthly, quarterly, or annual compounding to match your account.
Is my money safe in a savings account?
Deposits at FDIC-insured banks are protected up to $250,000 per depositor, per insured bank, per ownership category. If your bank fails, the FDIC covers your balance up to that limit. Credit unions carry equivalent protection through the NCUA.
Do I pay taxes on savings account interest?
Yes. The IRS taxes savings interest as ordinary income in the year you earn it, and banks send Form 1099-INT when interest reaches $10 or more. The calculator shows before-tax growth, so your actual take-home is slightly lower.
How much should I save each month?
A common guideline is the 50/30/20 rule: about 20% of after-tax income toward savings and debt payoff. For a dedicated emergency fund, aim for 3 to 6 months of expenses in an accessible savings account, then redirect new deposits toward longer-term goals.
What is the difference between APY and interest rate?
The interest rate (often quoted as APR) is the nominal rate before compounding is counted. APY folds compounding in, so APY is the number that tells you your true yearly growth. When compounding is more frequent than yearly, APY is always a little higher than the nominal rate.
How long does it take my savings to double?
Use the Rule of 72: divide 72 by your annual rate. At 6%, doubling takes about 72 / 6 = 12 years. Check it: $5,000 at 6% compounded annually for 12 years grows to 5,000 x 1.06^12 = $10,061, very close to a true double. The rule is an approximation, but it is accurate within a year or so for rates between 3% and 15%.
How much must I save monthly to reach $20,000 in 5 years?
Work backwards from the annuity formula. At 4% compounded monthly, the monthly rate is 0.04 / 12 = 0.003333 and there are 60 deposits. The payment needed is 20,000 x 0.003333 / ((1.003333)^60 - 1) = 20,000 x 0.003333 / 0.220997 = $301.66 a month. Saving $302 a month at 4% therefore reaches $20,000 in 5 years with no starting deposit.
Sources
- FDIC: deposit insurance coverage, $250,000 per depositor per insured bank
- IRS: Topic 403, interest received is taxable as ordinary income
Key takeaways
- Bookmark this tool to rerun your projection whenever your rate or contribution changes.
- $10,000 plus $500 a month at 4% APY for 10 years grows to about $88,533.
- Interest earned is future value minus everything you deposited: here, $18,533.
- APY includes compounding; compare APYs when shopping for accounts.
- US bank deposits are FDIC-insured up to $250,000 per depositor.
- Rate matters far more than compounding frequency; contributions matter most of all.
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