In plain words: tell the calculator what you have now, how much you will add each month and the interest rate. It shows the balance you could end up with, how much is your own money and how much is interest. Add a goal and it works out the monthly amount you need.
Last updated by Hira Science Academy. Educational tool; see the limitations section below.
What this savings calculator does
This savings calculator projects how an opening balance and regular monthly deposits could grow when interest is added every month. It reports the final balance, how much you paid in, how much interest you earned, and a year-by-year table. If you enter a savings goal, it also works out the monthly deposit you would need and how long your current plan would take. Use it to compare scenarios such as saving more each month, starting earlier or accepting a different rate. For a single lump sum with no deposits, the compound interest calculator is the better fit. To decide how much you can realistically set aside, start with the monthly budget calculator.
How to use the savings calculator
- Enter your opening balance. Use 0 if you have no savings yet.
- Enter the monthly deposit you plan to add at the end of each month.
- Enter the annual interest rate your account pays. The calculator compounds it monthly.
- Enter the savings period in years.
- Optional: enter a savings goal to see the monthly deposit it needs and the time your current plan takes.
- Press Calculate and read the balance, the interest share and the yearly table.
The savings formula
What each symbol means
- \(P\) — opening balance
- The amount you already have at the start.
- \(D\) — monthly deposit
- The amount added at the end of each month.
- \(R\) — annual rate in percent
- For 4%, \(R = 4\) and \(i = 4 / 1200\).
- \(m\) — number of months
- Years multiplied by 12, rounded to the nearest month.
- \(G\) — savings goal
- The target balance you want at the end of the period.
If the rate is 0%, the formula simplifies to \(FV = P + D \times m\).
Worked examples
Example 1: $1,000 opening balance, $200 a month, 4% for 5 years
- Monthly rate: \(i = 4/1200 = 0.003333\). Months: \(m = 60\).
- Growth factor for deposits: \(((1+i)^{60} - 1)/i = 66.2990\).
- Opening balance grows to $1,221.00. Deposits grow to \(200 \times 66.2990 = \) $13,259.80.
- Balance: $14,480.79. You paid in $13,000.00, so interest is $1,480.79.
Example 2: starting from zero with $500 a month at 6% for 10 years
- Months: 120. Monthly rate: \(6/1200 = 0.005\).
- Balance: about $81,939.67.
- Contributions: $60,000.00. Interest: $21,939.67, roughly a third of your own deposits.
Example 3: how much per month to reach $10,000 in 3 years at 3%?
- Months: 36. Monthly rate: \(i = 0.03/12 = 0.0025\). Deposit growth factor: \(((1+i)^{36} - 1)/i = 37.6206\).
- With no opening balance: \(D = 10{,}000 / 37.6206 \approx\) $265.81 per month.
- Total paid in: $9,569.24. Interest supplies the rest of the $10,000.
- Enter 10000 in the goal box to check this yourself.
Example 4: converting an APY of 5% to the nominal rate used here
- This calculator compounds monthly with a nominal rate. For an advertised APY of 5%, use \(R = 1200 \times (1.05^{1/12} - 1)\).
- That gives a nominal rate of about 4.889%. Enter 4.889 in the rate field to reproduce a 5% APY.
How the monthly deposit changes the outcome
The deposit is the lever you control most directly. The table keeps the rate (4%) and period (10 years) fixed, starts from nothing and changes only the deposit.
| Monthly deposit | You pay in | Interest | Final balance |
|---|---|---|---|
| $100 per month | $12,000 | $2,725 | $14,725 |
| $250 per month | $30,000 | $6,812 | $36,812 |
| $500 per month | $60,000 | $13,625 | $73,625 |
Illustrative arithmetic only. Deposits at the end of each month, interest compounded monthly.
Why starting early matters
Time works on every deposit you make. Here the monthly amount ($300) and rate (5%) stay the same and only the length changes. Notice that the extra 10 years from year 20 to year 30 add much more interest than the first 10 years did.
| Period | You pay in | Interest | Final balance |
|---|---|---|---|
| 10 years | $36,000 | $10,585 | $46,585 |
| 20 years | $72,000 | $51,310 | $123,310 |
| 30 years | $108,000 | $141,678 | $249,678 |
Choosing the interest rate to enter
- Savings accounts
- Use the rate the account pays. If it is quoted as an APY or AER, convert it to a nominal rate (see Example 4) or enter a slightly lower rate to stay cautious.
- Variable rates
- Many savings rates change. Run the calculator at a lower and a higher rate to see a range.
- Investments
- Market returns are uncertain and can be negative. Use the calculator for what-if planning, not as a forecast.
- Tax-advantaged accounts
- Accounts such as an IRA in the US, an ISA in the UK or a TFSA in Canada have their own contribution limits and rules. The calculator ignores them, so check official guidance.
Common savings goals the calculator can help plan
- Emergency fund. A common rule of thumb is three to six months of essential spending. Add up your essentials in the budget calculator, then enter that total as your goal.
- Down payment or deposit. Enter the target, the years until you need it and a cautious rate.
- Education fund. Long periods let compounding do more work. Try several deposit levels.
- Travel, wedding or large purchase. Short goals earn little interest, so the monthly deposit does most of the work.
- Paying down a loan instead. Compare the interest you would earn with the interest you would save using the loan repayment calculator's extra-payment option.
Common mistakes to avoid
- Using an APY as the nominal rate. The result will be slightly high. Convert it first.
- Forgetting the deposit timing. Deposits here are made at the end of each month. Depositing at the start of the month earns a little more.
- Entering yearly deposits as monthly. Divide an annual amount by 12.
- Ignoring inflation. A goal of $20,000 in ten years will have less buying power than $20,000 today.
- Assuming the rate never changes. Re-run the numbers when your account rate changes.
- Skipping the goal check. A larger balance is not useful if it still misses the target. Enter the goal to see the gap.
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Assumptions and limitations
- Constant rate and deposit. The rate and the monthly amount stay the same throughout.
- End-of-month deposits and monthly compounding. Starting-of-month deposits or different compounding would change the result slightly.
- No tax, fees or inflation. Real accounts can include them.
- Rounding. Months are rounded to the nearest whole month, and money is shown to two decimal places.
- Privacy. The maths runs in your browser. The numbers you type are not sent to a Hira Academy calculation server. Like the rest of the site, the page loads Google Analytics and advertising scripts; see the Privacy Policy.
Frequently asked questions about the Savings Calculator
How do I calculate savings with monthly deposits?
Use FV = P(1+i)^m + D × ((1+i)^m − 1) / i, where P is the opening balance, D the monthly deposit, i the monthly interest rate (annual rate ÷ 12) and m the number of months. For $1,000 opening, $200 a month, 4% and 5 years the result is about $14,480.79.
How much should I save each month to reach a goal?
Enter your goal in the optional goal box. The calculator solves for the monthly deposit that reaches it by the end of your period. For example, reaching $10,000 in 3 years at 3% from zero needs about $265.81 a month.
What interest rate should I enter?
Enter the nominal annual rate your account pays. If you only know an APY, convert it to a nominal rate or enter a slightly lower figure to stay cautious. For variable or investment returns, test a low and a high rate.
Are deposits made at the start or the end of the month?
The calculator assumes deposits at the end of each month, a common and slightly cautious convention. Deposits at the start of the month would earn one extra month of interest each.
How often is the interest compounded?
Monthly. The annual rate is divided by 12 and applied to the balance each month, then the deposit is added.
Does the calculator include taxes, fees or inflation?
No. Taxes, account fees and inflation reduce real-world results. Treat the figure as a pre-tax, pre-fee estimate and subtract expected costs from the rate if you want a cautious view.
What if my interest rate is 0%?
The balance is simply the opening balance plus all deposits. The calculator handles a 0% rate without dividing by zero.
How big should an emergency fund be?
A common rule of thumb is three to six months of essential spending, but the right amount depends on your job stability, dependants and insurance. Use the monthly budget calculator to total your essentials.
Is it better to save a lump sum or monthly?
Money invested earlier earns interest for longer, so a lump sum available now usually grows more than the same total spread over time. Most people save monthly because that is how income arrives. Compare both with the compound interest calculator and this one.
Are the results guaranteed?
No. They are estimates based on a constant rate and fixed deposits. Real accounts, rates and contributions change.
Is my data stored or sent anywhere?
No. The calculation runs in your browser and the values you type are not sent to a Hira Academy calculation server.
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