Quick guide
How to use this calculator
- Enter the balance, rate, timing, fee, or contribution assumptions named by the fields.
- Use one currency and follow the stated nominal, effective, simple-interest, or compounding convention.
- Review the calculator-specific assumptions before comparing accounts or making a savings decision.
Calculation method
Calculation method
Taxable interest = max(gross interest − entered allowance, 0). Tax = taxable interest × entered tax rate. Net interest = gross interest − tax.
Entered fixed decimals are parsed exactly. Compound projections use stable exponential forms and preserve zero-rate cases exactly; money rounds only for display and a supported nonzero amount is not replaced by a misleading zero.
Worked example
Worked example
Gross interest of 1,000 with a 200 allowance and 25% tax rate gives 200 tax and 800 net interest.
Taxable interest = max(gross interest − entered allowance, 0). Tax = taxable interest × entered tax rate. Net interest = gross interest − tax.
Supported inputs
Precision and limits
Visible input limits
Amounts accept up to 30 digits and 12 decimal places and are capped at 1e12 per input. Rates are capped at 1000%. Most projections are capped at 1,200 months or 100 years; narrower whole-number limits appear in field labels.
International scope
No currency, institution, current market rate, deposit-insurance rule, tax system, regulatory disclosure, or jurisdiction-specific product term is assumed.
Decision boundary
Results are arithmetic scenarios from visitor-entered assumptions, not account quotations, forecasts, tax advice, legal determinations, deposit guarantees, or recommendations.
Calculator-specific assumptions
No jurisdiction, tax year, filing status, withholding rule, or legal tax treatment is assumed. Enter a rate and allowance only when they apply to your situation.