PFCHow to use this calculator
Savings grow through both deposits and interest. Use this calculator to separate the money you contribute from the growth produced by a constant annual percentage yield over your selected period.
- Enter your starting savings balance and planned monthly deposit.
- Enter an APY and the number of years you want to model.
- Review the projected balance, total contributions, interest, and monthly schedule.
Illustrative example
Starting with $10,000.00, depositing $250.00 each month, and earning 4% APY for 10 years produces an estimated $51,476.41, including $11,476.41 in interest.
These example values are for explanation. They are not current market quotes or personalized recommendations.
Calculation method
The equivalent monthly rate is (1 + APY)^(1/12) − 1, using APY as a decimal. Each month, interest is applied to the opening balance and then the new deposit is added. Interest is rounded to cents.
Assumptions and limitations
APY is converted to an equivalent monthly rate, with interest rounded to cents monthly and deposits made at month end. APY stays constant. Results are nominal dollars before taxes, fees, withdrawals, and inflation. This is a growth illustration, not a guaranteed return.
Savings growth calculator FAQs
Choose a question to read the answer, then try your own numbers in the free calculator.
How does compound interest grow savings?
Compound interest means earning interest on both your deposits and previously earned interest. This calculator converts your APY into an equivalent monthly rate and applies it to the opening balance each month before adding the new deposit.
Should I enter APY or an interest rate?
Enter APY, the annual percentage yield that already reflects compounding. The calculator converts that annual yield to a monthly rate; entering a quoted interest rate instead of APY can give a different result.
Are deposits made at the beginning or end of the month?
This model makes deposits at month end, so a new deposit starts earning interest the following month.
Does this adjust for inflation or tax?
No. The result is in nominal dollars before taxes and fees. Purchasing power and after-tax interest may be lower.
Will my savings account keep the same APY?
Not necessarily. The calculator holds APY constant for comparison; it does not predict future bank rates.
PFC provides mathematical planning estimates. Tax and retirement rules in these tools are for 2026 and do not update automatically. Check the cited sources and the terms that apply to your situation.