How we calculate
Reviewed 23 October 2026. Calculators use the inputs shown on the page. Rounding, dates, units, payment timing, and jurisdiction can change a result.
Percentages
To find a percentage of an amount, multiply the amount by the percentage divided by 100. For example, 15% of 240 is 36. Percentage change divides the change by the original amount; an original amount of zero has no defined percentage change.
Mortgage payments
The standard mortgage tool assumes a fixed annual interest rate and monthly payments. For principal P, monthly rate r, and n payments, the principal-and-interest payment is P × r ÷ (1 − (1 + r)−n). At zero interest, the payment is P ÷ n.
For a $300,000 loan at 6% over 30 years, monthly principal and interest are approximately $1,798.65. Taxes, insurance, fees, and lender rules can add to the amount payable.
Currency conversion
Conversion multiplies the amount by the selected rate. The fee is deducted from the converted amount. The built-in rates are undated illustrative examples, not current exchange quotes. Supply a rate from your bank or exchange provider when planning an actual transaction.
U.S. income-tax estimates
The income-tax tool uses separate 2024, 2025, and 2026 federal brackets, standard deductions, and Social Security wage limits. The 2026 figures come from IRS Revenue Procedure 2025-32 and the Social Security Administration.
The tool estimates selected deductions and nonrefundable dependent credits. It uses adjusted gross income as an approximation of modified adjusted gross income. It does not implement a full tax return, all eligibility rules, alternative minimum tax, net investment income tax, refundable credits, capital-loss carryovers, or every state’s tax rules. Social Security benefit taxation is simplified to 85% of benefits. IRA and student-loan deductions do not model all eligibility phaseouts. Tips and overtime are treated as income; special qualified tips, overtime, and car-loan-interest deductions are not modeled. High-income itemized deduction limits and all 2026 charitable-deduction changes are not fully modeled.
Use the IRS Tax Withholding Estimator or a qualified tax professional for filing and withholding decisions.
Health tools
Health results are educational estimates. Formulas and reference ranges may not fit children, pregnancy, athletes, or people with particular medical conditions. They do not diagnose conditions or prescribe treatment.