Money Calculators
Use this savings interest calculator to estimate future balance and interest earned from a starting balance, monthly deposits, APY, and time.
Live calculator
60 monthly compounding periods.
Projected balance minus deposits and starting balance.
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.
Quick answer
Savings Interest Calculator calculates future savings balance from starting balance, monthly deposit, APY, and years. The visible formula is Future balance = starting balance x (1 + r)^n + monthly deposit x (((1 + r)^n - 1) / r).
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
Example
Calculator use
Before relying on it
Details
These notes make the assumptions explicit, especially where the same search query can mean slightly different things.
APY already reflects compounding over a year. This calculator turns the APY into a monthly projection for planning.
The estimate assumes the same monthly deposit throughout the period. Irregular deposits should be averaged or tested separately.
Savings APYs can change, so long projections are best treated as scenarios rather than guarantees.
Benchmarks
The calculator is a decision aid, not a fixed rule. Use the output to compare scenarios and document your assumptions. Benchmark ranges are broad planning heuristics unless this page names a specific source for the range.
Interest growth is modest, so deposits drive most of the balance.
A higher APY can make a visible difference over several years.
Interest matters more as the balance and time horizon grow.
Calculator accuracy
The formula, inputs, example, and limitations are shown so the result is checkable, not just a number in a box.
Future balance = starting balance x (1 + r)^n + monthly deposit x (((1 + r)^n - 1) / r)
Starting balance, Monthly deposit, APY, Years
Money results are planning estimates. Actual taxes, account terms, rates, fees, timing, local rules, and provider policies can change the real-world result.
June 6, 2026
Toolkit Shelf. Savings Interest Calculator. Last reviewed June 6, 2026. https://toolkitshelf.com/tools/savings-interest-calculator
FAQ
Apply the periodic interest rate to the balance over time, adding monthly deposits if you make them.
APY reflects annual yield including compounding. This calculator treats the APY you enter as a monthly compounding estimate.
No. Interest income may be taxable, but this calculator estimates gross interest before taxes.
No. Use it for planning and comparison. Real decisions can change after exact rates, balances, fees, taxes, account terms, timing, and personal details are verified.
Small changes in rates, payment timing, taxes, fees, balances, or income can materially change the result, so the assumptions need to stay visible.
Different tools may use different rounding, assumptions, default rates, methods, formulas, or input timing. Compare the visible method and inputs before relying on the output.