How to use this savings calculator
- Pick a question. “Future balance” projects what you will have, “Time to goal” shows how long a target takes, and “Monthly needed” tells you what to set aside each month.
- Enter what you have now and what you will add. The initial deposit can be $0. Monthly deposits are assumed to arrive at the end of each month.
- Enter your account’s APY. The default is 4%, a typical rate among top online high-yield savings accounts in late September 2026; use the APY your bank shows you.
- Add details if you like. Under “Deposit increase & taxes” you can raise your monthly deposit each year and apply your tax rate on interest. Results update as you type, and “Copy link” saves the scenario.
Savings formulas
Savings accounts advertise an APY (annual percentage yield), which already includes compounding. To work month by month, convert it to an equivalent monthly rate and grow the starting balance and each deposit:
FV = P × (1 + r)^n + D × ((1 + r)^n − 1) ÷ r, where r = (1 + APY)^(1/12) − 1
- FV
- balance after n months
- P
- initial deposit
- D
- deposit at the end of each month
- r
- monthly rate: (1 + APY)^(1/12) − 1
- n
- number of months
Worked example
With the default inputs, P = $5,000, D = $200, APY = 4% and n = 60 months. The monthly rate is (1 + 0.04)1/12 − 1 = 0.003274, and (1 + r)60 = (1 + APY)5 = 1.216653. The starting balance grows to $5,000 × 1.216653 = $6,083.26. The deposits grow to $200 × (1.216653 − 1) ÷ 0.003274 = $13,235.80. Together that is $19,319.07, matching the calculator.
Time to reach a goal
Solving the same equation for n gives the number of months to reach a goal G:
n = ln((D + G × r) ÷ (D + P × r)) ÷ ln(1 + r)
For a $25,000 goal with the same inputs, n = 80.89 months, so the balance first reaches the goal with the deposit at the end of month 81 (6 years 9 months). Rearranged for the deposit instead, D = (G − P(1 + r)n) × r ÷ ((1 + r)n − 1): reaching $25,000 in exactly 5 years from $5,000 takes $285.84 a month.
How much will monthly savings grow?
Balance from monthly deposits alone (starting at $0) at 4% APY, deposits at the end of each month, before taxes. Your own rate will change over time, so use the calculator for your exact numbers.
| Monthly deposit | 1 yr | 3 yrs | 5 yrs | 10 yrs | 20 yrs |
|---|---|---|---|---|---|
| $50 | $611 | $1,907 | $3,309 | $7,335 | $18,192 |
| $100 | $1,222 | $3,814 | $6,618 | $14,670 | $36,384 |
| $200 | $2,444 | $7,628 | $13,236 | $29,339 | $72,768 |
| $500 | $6,109 | $19,071 | $33,090 | $73,348 | $181,921 |
| $1,000 | $12,218 | $38,141 | $66,179 | $146,696 | $363,842 |
High-yield savings vs. the national average rate
The rate you earn varies a lot between banks. The FDIC’s national average savings rate was 0.37% as of Sep 21, 2026 (FDIC national rates), an average of the rates paid by insured banks and credit unions, weighted by each institution’s share of deposits. Top online high-yield accounts were paying around 4% APY on Sep 28, 2026, according to Bankrate’s list of high-yield savings accounts. Here is what that gap means over time:
| Scenario | At 4% APY | At 0.37% (national avg.) | Difference |
|---|---|---|---|
| $10,000 left for 5 years | $12,167 | $10,186 | $1,980 |
| $200 a month for 10 years | $29,339 | $24,445 | $4,894 |
| $5,000 plus $500 a month for 20 years | $192,876 | $129,907 | $62,969 |
A single $10,000 deposit earns $1,980 more over 5 years at the higher rate. Rates on savings accounts are variable and can drop at any time, so compare the current APY, fees and minimum balance before moving money, and confirm the bank is FDIC-insured.
How much should you keep in an emergency fund?
The Consumer Financial Protection Bureau says the right amount depends on your situation, and suggests starting from the kinds of unexpected expenses you have faced before and what they cost (CFPB emergency fund guide). Even a small cushion helps if your income varies or you live paycheck to paycheck. The CFPB describes a bank or credit union account as generally one of the safest places to keep it.
Use “Time to goal” to plan it. For example, setting aside $100 a month at 4% APY reaches a first $1,000 cushion in 10 months; then raise the target step by step. Automatic transfers on payday make the habit easier to keep.
Ways to grow your savings faster
- Deposit more before chasing rate. In the default example, deposits make up $17,000 of the $19,319 balance; the amount you save matters most over short periods.
- Earn a competitive APY. At 4%, a lump sum doubles in about 17.7 years; at the 0.37% national average it would take about 188 years.
- Lock in a rate for money you will not touch. A certificate of deposit pays a fixed rate for a set term; compare with our CD calculator.
- Plan for taxes. Interest is taxed as ordinary income each year. For long-term goals, see how tax-free growth changes the picture with the compound interest calculator.
- Mind inflation. A balance that grows more slowly than prices loses buying power; check it with the inflation calculator.
Frequently asked questions
How much will I have if I save $200 a month?
Saving $200 a month at 4% APY with nothing to start builds $13,236 in 5 years, $29,339 in 10 years and $72,768 in 20 years, assuming the rate stays the same and deposits arrive at the end of each month. Savings rates are variable, so treat long projections as estimates and recheck them when your rate changes.
How is interest on a savings account calculated?
Banks figure interest every day on the balance, using a daily rate of at least 1/365 of the interest rate under Regulation DD, and then credit it on a schedule such as monthly. The APY folds that compounding into one annual number. This calculator converts the APY to an equivalent monthly rate, (1 + APY)1/12 − 1, which is 0.3274% a month at 4% APY.
How long will it take to save $25,000?
Starting with $5,000 and adding $200 a month at 4% APY, you reach $25,000 in 6 years 9 months. Interest does some of the work: without it, the same deposits would take 8 years 4 months.
What is the difference between APY and the interest rate?
The interest rate is the annual rate before compounding; the annual percentage yield (APY) includes the effect of compounding over a 365-day year. Regulation DD requires banks to disclose the APY, which makes it the fair way to compare accounts. Because this calculator asks for the APY, you do not need to know how often your bank compounds.
Is the interest on my savings account taxable?
Yes. The IRS treats interest from bank savings, money market accounts and CDs as taxable income, and your bank sends Form 1099-INT if it paid you $10 or more. In the example above, a 24% tax rate trims the interest from $2,319 to about $1,729. Enter your rate under “Deposit increase & taxes” to see your own after-tax balance.
Is money in a high-yield savings account safe?
Deposits at an FDIC-insured bank are protected up to $250,000 per depositor, per insured bank, for each account ownership category, including savings and money market deposit accounts. Many high-yield accounts are offered by online banks; check that the bank itself (not just an app or partner) is FDIC-insured, and keep balances within the coverage limits.