Formula
Savings interest formula
Future balance = starting balance x (1 + r)^n + monthly deposit x (((1 + r)^n - 1) / r)This estimate assumes monthly compounding and steady monthly deposits.
Money Calculators
Savings Interest Calculator
Use this savings interest calculator to estimate future balance and interest earned from a starting balance, monthly deposits, APY, and time.
Reviewed May 25, 2026EstimateFormula shown
Live calculator
Savings interest
Future balance$26,402.64
60 monthly compounding periods.
Interest earned$3,402.64
Projected balance minus deposits and starting balance.
Total deposits$23,000.00
Starting balance plus monthly deposits.
How to use
Steps
- Enter starting balance.
- Enter monthly deposit.
- Enter APY and years.
- Compare future balance with deposits to estimate interest earned.
Example
Sample calculation
Starting balance$5,000
Monthly deposit$300
5 years at 4.5%$26,426
Calculator use
Best for
- Quick future savings balance from starting balance, monthly deposit and apy.
- Personal finance scenarios before changing a budget, loan, savings goal, or purchase plan.
- Monthly cash flow, affordability, debt payoff, or future-value estimates.
- Assumption checks before talking with a lender, tax preparer, employer, or financial professional.
Before relying on it
Check first
- Entering starting balance, monthly deposit and apy from different time periods or scenarios.
- Mixing gross income, take-home income, one-time costs, and monthly costs in the same comparison.
- Forgetting taxes, fees, insurance, irregular bills, or minimum payments when using an estimate.
- Treating a planning estimate as a quote, tax filing result, approval decision, or guaranteed return.
Benchmarks
How to read the result
The calculator is a decision aid, not a fixed rule. Use the output to compare scenarios and document your assumptions.
0% - 2%Low yield
Interest growth is modest, so deposits drive most of the balance.
3% - 5%Higher savings yield
A higher APY can make a visible difference over several years.
Longer timeMore compounding
Interest matters more as the balance and time horizon grow.
Calculator accuracy
Methodology and assumptions
The formula, inputs, example, and limitations are shown so the result is checkable, not just a number in a box.
Formula
Future balance = starting balance x (1 + r)^n + monthly deposit x (((1 + r)^n - 1) / r)
Inputs used
Starting balance, Monthly deposit, APY, Years
Limitations
Results are estimates for quick planning and should be checked before important financial, legal, tax, health, or business decisions.
Last reviewed
May 25, 2026
Cite this page
Toolkit Shelf. Savings Interest Calculator. Retrieved May 25, 2026, from https://toolkitshelf.com/tools/savings-interest-calculator
FAQ
Common questions
How do I calculate savings interest?
Apply the periodic interest rate to the balance over time, adding monthly deposits if you make them.
Is APY the same as interest rate?
APY reflects annual yield including compounding. This calculator treats the APY you enter as a monthly compounding estimate.
Does this include taxes?
No. Interest income may be taxable, but this calculator estimates gross interest before taxes.