1. Scope
Converts gross salary to paycheck-level take-home using simplified US tax assumptions (federal brackets + FICA + flat state rate). It is not tax advice — payroll systems compute withholding differently based on W-4 elections.
2. Inputs and outputs
Inputs
- annualSalary number (currency)
- filingStatus enum
single | married-joint | head-of-household.
- payFrequency enum
weekly | biweekly | semimonthly | monthly.
- stateTaxRate percent default: 0
- pretaxDeductions number (currency/year) default: 0
401(k), HSA, etc.
Outputs
- federalIncomeTax
Bracketed on taxable income minus standard deduction and pre-tax.
- ficaTax
7.65% up to OASDI wage base + Medicare 1.45% above.
- stateTax
Flat-rate state tax on taxable income.
- netAnnual
annualSalary − all taxes − pre-tax deductions.
- netPerPaycheck
netAnnual / pay periods.
Engine source: src/lib/salary-calculator/engine.ts
3. Formula / scoring logic
taxable_income = salary - standard_deduction - pretax
federal_tax = bracket_tax(taxable_income, filing_status)
fica = min(salary, ssa_wage_base) * 0.062 + salary * 0.0145
state_tax = salary * state_rate
net_annual = salary - federal - fica - state - pretax4. Assumptions
- Uses 2024 US federal tax brackets, standard deduction, and SSA wage base ($168,600).
- State tax is a flat rate — does not model progressive state brackets, local taxes, or SDI/SUI.
- Assumes single-job W-2 income with standard deduction, no dependents or credits.
5. Data sources
- US IRS — 2024 tax brackets and standard deduction as of 2024
- US SSA 2024 wage base as of 2024
6. Known limitations
- Does not model itemised deductions, above-the-line adjustments, credits (CTC, EITC, education), or AMT.
- FICA cap applies only to OASDI; Medicare has no cap and adds a 0.9% surtax above $200k single / $250k joint which the tool ignores.
7. Reproducibility
Input
annualSalary = $100,000, filing = single, payFrequency = biweekly, stateRate = 5%, pretax = $0.
Expected output
federal ≈ $14,260, fica = $7,650, state = $5,000, net_annual ≈ $73,090, per_paycheck ≈ $2,811 (directional, 2024).
8. Change log
- 2026-04-24 methodology page first published.
Worked example
Run live against the same engine this site ships
(/engines/salary-calculator.js).
The inputs and outputs below are recomputed on every build and
independently re-verified in CI — they are never hand-authored.
Input
- tool
- salary_calculator
- mode
- annual
- hourly_rate
- 38
- annual_salary
- 85000
- hours_per_week
- 40
- weeks_per_year
- 52
- overtime_hours_per_week
- 0
- overtime_multiplier
- 1.5
- filing_status
- single
- pre_tax_deductions_annual
- 0
- other_annual_income
- 0
- compare_annual_salary
- 95000
Output
- grossAnnual
- 85000
- grossMonthly
- 7083.33
- grossBiweekly
- 3269.23
- estimatedTakeHomeAnnual
- 75130
- estimatedTakeHomeMonthly
- 6260.83
- estimatedTakeHomeBiweekly
- 2889.62
- overtimeAnnualGross
- 0
- taxBreakdown.taxableIncome
- 68900
- taxBreakdown.federalTax
- 9870
- taxBreakdown.effectiveTaxRatePercent
- 11.61
- taxBreakdown.standardDeduction
- 16100
- comparisonDeltaAnnualTakeHome
- 7800
- assumptionsEcho.mode
- annual
- assumptionsEcho.hourlyRate
- 38
- assumptionsEcho.annualSalary
- 85000
- assumptionsEcho.hoursPerWeek
- 40
- assumptionsEcho.weeksPerYear
- 52
- assumptionsEcho.overtimeHoursPerWeek
- 0
- assumptionsEcho.overtimeMultiplier
- 1.5
- assumptionsEcho.filingStatus
- single
- assumptionsEcho.preTaxDeductionsAnnual
- 0
- assumptionsEcho.otherAnnualIncome
- 0
- assumptionsEcho.compareAnnualSalary
- 95000
- warnings[0]
- Federal tax estimate uses 2026 bracket and standard-deduction assumptions for planning purposes only.
- warnings[1]
- Estimate excludes state/local taxes, payroll taxes, credits, and individualized deductions.
Frequently asked questions
- What does the Salary / Paycheck Calculator calculate?
- Converts gross salary to paycheck-level take-home using simplified US tax assumptions (federal brackets + FICA + flat state rate). It is not tax advice — payroll systems compute withholding differently based on W-4 elections.
- What inputs does the Salary / Paycheck Calculator need?
- It takes 5 inputs: annualSalary, filingStatus, payFrequency, stateTaxRate (default 0), pretaxDeductions (default 0). Outputs returned: federalIncomeTax, ficaTax, stateTax, netAnnual, netPerPaycheck.
- What formula does the Salary / Paycheck Calculator use?
- The exact computation is: taxable_income = salary - standard_deduction - pretax; federal_tax = bracket_tax(taxable_income, filing_status); fica = min(salary, ssa_wage_base) * 0.062 + salary * 0.0145; state_tax = salary * state_rate; net_annual = salary - federal - fica - state - pretax
- Can I verify the Salary / Paycheck Calculator with a worked example?
- Yes. With annualSalary = $100,000, filing = single, payFrequency = biweekly, stateRate = 5%, pretax = $0. the tool returns federal ≈ $14,260, fica = $7,650, state = $5,000, net_annual ≈ $73,090, per_paycheck ≈ $2,811 (directional, 2024).
- Where does the Salary / Paycheck Calculator get its benchmark data?
- Reference data is sourced from: US IRS — 2024 tax brackets and standard deduction (as of 2024); US SSA 2024 wage base (as of 2024).
- What can the Salary / Paycheck Calculator not tell me?
- Known limitations: Does not model itemised deductions, above-the-line adjustments, credits (CTC, EITC, education), or AMT. FICA cap applies only to OASDI; Medicare has no cap and adds a 0.9% surtax above $200k single / $250k joint which the tool ignores.