Interest Calculator
Estimate simple or compound growth with regular deposits, tax, and inflation assumptions.
Formatting only. Enter your own rate and tax assumptions; no conversion or local tax rules are applied.
Growth assumptions
Deposits are made monthly and annually at the selected timing. Tax and inflation are optional estimates, not jurisdiction-specific calculations.
Balance and deposits
Ending balance share
Annual accumulation schedule
| Year | Deposit | Interest | Ending balance |
|---|
Detailed Breakdown
Simple vs. compound
Simple interest applies earnings to the starting principal only. Compound interest adds each period's net interest to the balance so later periods earn interest on prior growth.
Deposits and timing
Monthly contributions follow the selected month timing; the annual deposit is added at year end. Beginning-of-month monthly deposits receive one additional month of growth compared with end-of-month deposits.
Tax and inflation
The optional tax percentage is subtracted from each interest period. Inflation-adjusted value divides the ending balance by the assumed cumulative price growth. These are simplified estimates, not local tax advice.
Limits
Rates are assumed fixed. Account fees, changing rates, withdrawal restrictions, contribution limits, and account-specific tax rules are not modeled.
Examples
With a 10,000 starting balance and a steady 5% annual rate, compound interest earns returns on prior interest; simple interest applies the rate only to original principal. Recurring deposits and tax assumptions change the projection.
FAQ
How are simple and compound interest different?
Simple interest is based on original principal. Compound interest is calculated on the accumulated balance, including prior interest.
When are recurring deposits added?
The selected timing determines whether each monthly deposit starts earning in that period or the next.
Are tax results jurisdiction-specific?
No. The tax field is a simple assumption, not local tax advice or an account-specific tax calculation.
Related Calculators
- Simple Interest Calculator — calculate interest on original principal.
- Compound Interest Calculator — inspect compounding and equivalent rates.
- Savings Calculator — project deposits and account growth.
Internal links: compare the Simple Interest Calculator with the compounding model in the Compound Interest Calculator.