Simple Savings Calculator
Enter your starting balance, any regular deposits, interest rate and time horizon to see your future savings balance alongside total interest earned and a year-by-year growth schedule. Choose from nine compounding frequencies, adjust for inflation, and switch between five solve modes to reverse-calculate any unknown. Results update instantly as you type.
How this savings calculator works
Enter your starting balance (initial deposit), any regular contributions and how often you make them, the annual interest rate your account offers, and how long you plan to save. The calculator compounds interest at the frequency you select and adds your periodic deposits at the end of each contribution period. The result is the projected future balance, split into the money you put in (total contributions) and the interest your account has generated for you. If you want to work backward from a savings goal, use the "I want to find my" menu to reverse-solve for any unknown: the initial deposit you need today, the regular deposit amount, the time to reach a target, or the interest rate required.
The compound interest formula
Compound interest grows your balance by earning interest on interest already credited. The future value of a lump sum is: FV = P x (1 + r/n)^(n x t), where P is the principal, r is the annual rate as a decimal, n is the number of compounding periods per year, and t is the time in years. For periodic deposits made at the end of each period, the future value of an annuity adds: FV_deposits = D x [(1 + r_d)^k - 1] / r_d, where D is the deposit amount, r_d is the effective rate per deposit period, and k is the total number of deposits. Your total future balance is the sum of both. More frequent compounding (daily versus annually) increases the effective yield slightly, which is captured by the APY figure shown.
APY versus nominal interest rate
The nominal rate (sometimes called the stated rate or APR) is what banks advertise. The Annual Percentage Yield (APY) is what you actually earn after compounding is applied. For a 4.50% nominal rate compounded monthly, the APY is (1 + 0.045/12)^12 - 1, which is approximately 4.594%. The gap between them widens with higher rates and more frequent compounding. When comparing savings accounts, the APY is the apples-to-apples figure because it already accounts for how often interest is credited.
Inflation and real returns
Your nominal balance is the number on your account statement, but its real purchasing power depends on inflation. If prices rise 2.5% per year and your savings grow 4.5%, your real return is roughly 2.0% per year (more precisely: (1 + 0.045) / (1 + 0.025) - 1). The "real balance" output shows your projected balance expressed in today's dollars, so you can see how much buying power you are actually accumulating. In periods when the savings rate is below inflation, the real return is negative: you have more dollars but they buy less.
Typical savings account APY ranges (U.S.)
| Account type | Typical APY range | Notes |
|---|---|---|
| Traditional bank savings | 0.01% - 0.10% | National average is very low |
| Online HYSA | 4.00% - 5.50% | Best rates for liquid savings in 2024-2025 |
| Money market account | 3.50% - 5.00% | May require higher minimum balance |
| 1-year CD | 4.50% - 5.50% | Rate locked; early withdrawal penalty |
| 5-year CD | 3.50% - 4.50% | Longer lock-in for guaranteed rate |
| I-Bonds (U.S.) | Variable (inflation-linked) | Capped at $10,000/year per person |
Representative rates as of 2025. Rates change frequently - check with your institution.
Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is calculated only on the original principal: if you deposit $1,000 at 5% for 3 years you earn $50 per year, or $150 total. Compound interest is calculated on the principal plus interest already earned, so the same $1,000 at 5% compounded annually grows to $1,157.63 after 3 years because each year's interest is added to the base for the next calculation. Most savings accounts, high-yield savings accounts and certificates of deposit use compound interest.
How often should interest be compounded for the best return?
All else equal, more frequent compounding produces a slightly higher effective yield. Daily compounding beats monthly, which beats quarterly, which beats annual. In practice, the difference for realistic rates is small: at 4.50% nominal, daily compounding yields an APY of about 4.603% versus 4.594% for monthly. The difference is more meaningful at very high rates. When comparing accounts, always compare APY rather than the nominal rate because APY already reflects compounding frequency.
How do I use this calculator to find out how long it takes to reach a savings goal?
Select "Time needed (years)" from the "I want to find my" menu. Enter your current balance, your regular deposit amount, the interest rate, and your target balance. The calculator uses an iterative method to find the number of years at which the projected balance crosses your goal, then displays that duration alongside the full breakdown.
Does this calculator account for taxes on interest?
Yes. Enter your marginal tax rate in the "Annual tax on interest" field. The calculator applies the tax to the interest earned each year before it is reinvested, which reduces the compounding base. This approximates the real-world effect of paying income tax on savings interest annually. If you are saving inside a tax-advantaged account such as a Roth IRA or an ISA (UK), set the tax rate to 0.
What is APY and how is it different from the interest rate?
APY stands for Annual Percentage Yield. It is the effective yearly return you earn after compounding is taken into account. The interest rate (or nominal rate) is what the bank states before compounding. For example, a 4.50% nominal rate compounded monthly produces an APY of about 4.594%. Always compare savings accounts using APY because it captures the full effect of how often interest is credited.
Can I use this to plan for a specific savings goal?
Absolutely. Use the "Required periodic deposit" or "Required initial deposit" solve modes. Enter your target balance, the interest rate you expect, the time horizon, and any amount you already have or plan to contribute regularly. The calculator returns the missing piece you need to reach your goal on schedule.