Savings Calculator
See how a savings account grows. Enter a starting balance, a regular deposit and the interest rate, then choose how often interest compounds and when deposits land. Add a tax rate and inflation for an after-tax, todays-money view, or flip to goal mode to find the deposit needed to reach a target.
Formula
Worked example
2,000 start, 200 per month, 4% APY compounded monthly, deposits at end of month, 5 years: F = 1.040742, balance about 15,700, of which 13,700 is the money paid in and roughly 1,700 is interest. At a 22% tax rate you keep about 1,330 of that interest.
How the balance is calculated
The projection adds the future value of your starting balance to the future value of your stream of deposits. First it turns the APY into an effective annual growth factor F based on how often interest compounds, F = (1 + r/m)^m, or e^r for continuous compounding. That factor is converted to a per-deposit factor g so deposits made monthly, every two weeks, weekly or yearly all grow correctly. The starting balance grows by F^t, and each deposit grows from the moment it lands until the end of the term. Subtracting everything you put in leaves the interest the account earned.
Compounding frequency, deposit timing and APY
Compounding frequency controls how often interest is added: daily compounding earns slightly more than monthly at the same nominal rate. Savings accounts usually advertise an annual percentage yield (APY), which already reflects compounding within the year, so entering the APY and choosing a frequency keeps the result close to what the bank quotes. Deposit timing matters too. Money paid in at the start of each period earns one extra period of interest compared with paying at the end, which is why the start of period option produces a slightly higher balance.
Tax, inflation and saving for a goal
Interest on a taxable account is usually taxed, so entering your marginal tax rate shows the interest you actually keep. Inflation quietly erodes buying power, so the calculator also discounts the balance back to todays money at the inflation rate you set, which is the figure that really matters for a future purchase. Switch to goal mode to work the maths backwards: enter a target balance and the term, and the calculator solves for the deposit you need each period. These are planning estimates that assume a constant rate, so revisit them when your rate or savings change.
How compounding frequency changes a 4% rate
| Compounding | Periods per year | Effective annual yield |
|---|---|---|
| Annually | 1 | 4.000% |
| Quarterly | 4 | 4.060% |
| Monthly | 12 | 4.074% |
| Daily | 365 | 4.081% |
| Continuously | ∞ | 4.081% |
Effective annual yield on a 4% nominal rate at different compounding frequencies.
Frequently asked questions
What interest rate should I use?
Use the APY your bank advertises. High-yield online savings accounts often pay several times more than traditional accounts, so it is worth comparing before you enter a figure. Then pick the compounding frequency that matches the account, monthly is a safe default.
How do I work out the monthly deposit to hit a savings goal?
Switch the mode to "Deposit needed to reach a goal", enter the target balance, your starting balance, the rate and the number of years. The calculator solves for the deposit you need each period and shows the year by year path to the goal.
Does this include taxes and inflation?
Both are optional. Enter your marginal tax rate to see the interest you keep after tax, and an inflation rate to see the balance in todays money. Leave them at zero for a tax-free, nominal projection such as a sheltered or retirement account.
How is this different from an investment calculator?
The math is the same, but savings rates are typically lower and far more stable than investment returns. Savings prioritise safety and easy access; investments accept risk for the chance of higher long-run growth.