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Savings Interest Calculator

Use this savings interest calculator to estimate future balance and interest earned from a starting balance, monthly deposits, APY, and time.

Planning estimate

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.

Use this as a planning estimate. Taxes, fees, rates, account terms, provider policies, local rules, and timing can change real-world results.

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.

How to use

Steps

  1. Enter starting balance.
  2. Enter monthly deposit.
  3. Enter APY and years.
  4. 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

  • Estimating savings, budget, debt, tax, interest, retirement, or net-worth scenarios before changing a money plan.
  • Comparing monthly contributions, withdrawals, balances, interest rates, payoff order, or tax assumptions with the math visible.

Before relying on it

Check first

  • Treating an estimate as tax filing advice, investment advice, guaranteed return, or an official account balance.
  • Leaving out fees, taxes, inflation, irregular bills, employer benefits, penalties, changing rates, or timing differences.
  • Comparing scenarios with different time horizons, compounding assumptions, or gross versus after-tax amounts.

Details

What to know before using the result

APY inputCompounding included

APY already reflects compounding over a year. This calculator turns the APY into a monthly projection for planning.

Deposit timingSteady monthly additions

The estimate assumes the same monthly deposit throughout the period. Irregular deposits should be averaged or tested separately.

Rate changesNot locked

Savings APYs can change, so long projections are best treated as scenarios rather than guarantees.

Source notes

References used for this calculator

Investor.govProvides a compound interest calculator with initial investment, monthly contribution, time, interest rate, and compounding frequency inputs.FDICExplains savings accounts and deposit account basics.

Benchmarks

How to read the result

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 time: More compounding.

Interest matters more as the balance and time horizon grow.

Calculator accuracy

Methodology and assumptions

Formula, inputs, limitations and review record
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

Money results are planning estimates. Actual taxes, account terms, rates, fees, timing, local rules, and provider policies can change the real-world result.

Review record

Catalog QA baseline on June 6, 2026. This date marks the catalog-wide automated and editorial QA baseline, not a tool-specific expert review.

Cite this page

Toolkit Shelf. Savings Interest Calculator. 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.