THE NUMORIX GUIDE
How to use the Paycheck Calculator
Last reviewed September 14, 2026
What this calculator does
The UI converts an annual salary to gross pay for the selected frequency, then the engine reconstructs annual salary using 52 weekly, 26 biweekly, 24 semi-monthly, 12 monthly, or 1 annual period.
Formula and method
The UI converts an annual salary to gross pay for the selected frequency, then the engine reconstructs annual salary using 52 weekly, 26 biweekly, 24 semi-monthly, 12 monthly, or 1 annual period. It applies its hardcoded 2025 federal bracket table, a flat state-rate table, Social Security at 6.2% up to $168,600, and Medicare at 1.45%, then subtracts those period-level deductions from gross pay.
Variables and inputs
Enter annual salary, pay frequency, and a two-letter state code. Supported state rates include CA 9.3%, NY 6.85%, TX/FL/WA 0%, IL 4.95%, PA 3.07%, OH 4.79%, GA 5.49%, NC 4.5%, and a 5% default for an unrecognized code. No filing-status or deduction fields are present.
Worked example
For the default $75,000 annual salary, biweekly pay, and CA, gross pay is $75,000 / 26 = $2,884.62. The engine estimates $438.99 federal tax, $268.27 state tax, $178.85 Social Security, and $41.83 Medicare per check, for about $927.93 of deductions and $1,956.69 net pay.
How to interpret the result
This is a simplified gross-to-net estimate using the route's stored tax assumptions. Effective tax rate is the modeled deductions divided by gross pay; it is not a marginal rate, a tax-return liability, or a payroll statement.
Common mistakes to avoid
Enter annual salary even when viewing a monthly or biweekly result. Use a state abbreviation that the table recognizes, and remember that an unknown code silently uses the 5% default. Do not add a second federal deduction for a standard deduction that this engine does not model.
Assumptions and limitations
The federal brackets and Social Security wage base are hardcoded, state tax is flat, and the calculation omits filing status, standard or itemized deductions, credits, local tax, unemployment tax, benefits, retirement contributions, garnishments, overtime, and bonuses. The displayed tax estimate is not current-law payroll advice without review.