Enter your starting balance, monthly contribution, interest rate and time horizon to see exactly how your savings will grow. Results update instantly. Free, no signup required.
Initial Deposit ($) The amount you’re starting with today. If you’re opening a brand new savings account with nothing in it yet, enter 0.
Monthly Contribution ($) How much you’ll add each month. Even a small regular amount — $50 or $100 — makes a significant difference over time due to compounding. Enter 0 if you’re making a one-time deposit only.
Annual Interest Rate (%) The yearly interest rate your savings will earn. For reference: high-yield savings accounts in the US currently pay around 4–5% APY. Standard savings accounts pay much less — often under 1%. Use the actual rate your account offers, not a wishful estimate.
Time Period (years) How long you plan to save. Try different time horizons to see how dramatically compounding changes the outcome at 5, 10 and 20 years.
Compounding Frequency How often interest is calculated and added to your balance. Most savings accounts compound daily or monthly. More frequent compounding produces slightly higher returns — a 5% rate compounded daily yields more than 5% compounded annually.
Suppose you deposit $5,000 today, contribute $200 per month, at an annual rate of 4.5%, compounded monthly, over 10 years.
| Amount | |
|---|---|
| Total contributed | $29,000 |
| Interest earned | $8,947 |
| Final balance | $37,947 |
Of your final balance, almost $9,000 is money you never deposited — it was generated purely by compound interest on your previous interest. That gap between what you put in and what you end up with gets larger every year you stay invested.
Your savings growth is calculated using the standard compound interest formula:
A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) − 1) / (r/n)]
Where:
A = final balance
P = initial deposit (principal)
r = annual interest rate (as a decimal — e.g. 4.5% = 0.045)
n = compounding periods per year (12 for monthly, 365 for daily)
t = time in years
PMT = regular monthly contribution
The first part of the formula calculates growth on your initial deposit. The second part calculates the accumulated value of all your monthly contributions. Combined, they give you the total projected balance.
The same interest rate produces different results depending on how often it compounds:
| Compounding | Effective annual rate on 5% nominal |
|---|---|
| Annually | 5.000% |
| Quarterly | 5.095% |
| Monthly | 5.116% |
| Daily | 5.127% |
The differences are small over one year but compound significantly over decades. A $10,000 deposit at 5% over 30 years:
Compounded annually: $43,219
Compounded monthly: $44,677
Compounded daily: $44,812
Always check whether your savings account quotes a nominal rate or APY (Annual Percentage Yield). APY already accounts for compounding — if your account says APY, use that number directly and select “annually” as your compounding frequency to avoid double-counting.
Run three scenarios, not one. Calculate your result with your current savings rate, then with +$100/month more, then with +$200/month more. The difference at 10–20 years is often striking enough to change saving behaviour.
Be conservative with the interest rate. Use the rate your account actually pays today, not a projected future rate. Rates change. If you’re modelling long-term growth in a market-linked account, consider using a lower rate to build in a safety margin.
The starting amount matters less than the habit. The calculator will show you that $0 initial deposit with consistent $300/month contributions often produces a higher 10-year balance than $10,000 initial deposit with no ongoing contributions. Starting small consistently beats starting big once.
Compound interest means you earn interest not just on your original deposit, but on all the interest you’ve already earned. Each period, your interest is added to your balance — and in the next period, you earn interest on that larger balance. Over time this creates exponential rather than linear growth.
APR (Annual Percentage Rate) is the nominal annual interest rate before compounding. APY (Annual Percentage Yield) already accounts for the effect of compounding and reflects your actual annual return. Most savings accounts advertise APY. If your account quotes APY, use that figure and set compounding to “annually” in this calculator to avoid inflating the result.
The calculations are mathematically precise given the inputs you provide. Real-world results will differ because interest rates change over time, contributions may be irregular, and some accounts have fees or minimum balance requirements that affect the actual return. Use the results as a planning guide, not a guarantee.
No — the result shown is a nominal figure, meaning it doesn’t adjust for inflation. $37,947 in 10 years will have less purchasing power than $37,947 today. For a rough inflation-adjusted estimate, subtract the expected annual inflation rate from your interest rate before running the calculation. For example, if your rate is 4.5% and expected inflation is 2.5%, run the calculator at 2% to see real-terms growth.
A widely used framework is the 50/30/20 rule — 50% of take-home pay on needs, 30% on wants, and 20% on savings and debt repayment. For most people, the priority order is: emergency fund first (3–6 months of expenses), then high-interest debt repayment, then long-term savings. Use this calculator to find a monthly contribution that reaches your target balance within your chosen timeframe.
Use the actual current rate from your savings account or intended account. As a reference point: high-yield savings accounts currently pay approximately 4–5% APY in the US and comparable rates in other markets. Standard bank savings accounts often pay far less. The difference between 0.5% and 4.5% over 10 years on a $10,000 deposit is over $5,000 — choosing the right account matters as much as the contribution amount.
The calculator assumes consistent contributions every month. In practice, missing a payment simply means that month’s contribution doesn’t compound — your final balance will be slightly lower. The most important thing is resuming regular contributions rather than trying to “catch up” with a larger one-off payment.
This calculator shows you the outcome — but understanding how compound interest actually works, why the growth curve accelerates over time, and how to structure a savings plan for a specific goal is covered in detail in our full guide.
👉 How to Save Money: A Practical Guide — emergency funds, account types and a savings framework that works
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