What inputs does the Salary / Paycheck Calculator need?

It takes 6 inputs: mode (default annual), annual_salary, hourly_rate, filing_status (default single), pre_tax_deductions_annual (default 0), compare_annual_salary. Outputs returned: grossAnnual / grossMonthly / grossBiweekly, estimatedTakeHomeAnnual / Monthly / Biweekly, taxBreakdown.federalTax, taxBreakdown.ficaTax, taxBreakdown.effectiveTaxRatePercent, comparisonDeltaAnnualTakeHome.

Can I verify the Salary / Paycheck Calculator with a worked example?

Yes. With mode = annual, annual_salary = $100,000, filing_status = single, pre_tax_deductions_annual = $0. the tool returns taxableIncome = $83,900, federalTax = $13,170, ficaTax = $7,650, estimatedTakeHomeAnnual = $79,180, monthly ≈ $6,598.33, effectiveTaxRatePercent = 20.82.

Where does the Salary / Paycheck Calculator get its benchmark data?

Reference data is sourced from: US IRS — federal tax brackets and standard deduction (as of 2026); US SSA Social Security wage base (as of 2026).

What can the Salary / Paycheck Calculator not tell me?

Known limitations: Federal-only: no state, local, SDI, or SUI withholding is modeled. 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 the tool does not add the 0.9% Additional Medicare surtax above $200k single / $250k joint.

Salary Paycheck Calculator: How the Math Works

1. Scope

Converts gross pay to take-home using simplified US federal assumptions: federal income tax brackets plus employee-side FICA. It does not model any state or local tax. It is not tax advice — payroll systems compute withholding differently based on W-4 elections.

2. Inputs and outputs

Inputs

mode enum default: annual

annual | hourly.
annual_salary number (currency)

Used in annual mode.
hourly_rate number (currency)

Used in hourly mode, with hours_per_week, weeks_per_year, and overtime fields.
filing_status enum default: single

single | married_joint. Head-of-household is not modeled.
pre_tax_deductions_annual number (currency/year) default: 0

401(k), HSA, etc.
compare_annual_salary number (currency)

Optional second salary for the take-home delta output.

Outputs

grossAnnual / grossMonthly / grossBiweekly

Gross pay per period.
estimatedTakeHomeAnnual / Monthly / Biweekly

gross − federal income tax − employee FICA.
taxBreakdown.federalTax

Bracketed on gross + other income − pre-tax − standard deduction.
taxBreakdown.ficaTax

min(gross, wage base) × 6.2% + gross × 1.45%.
taxBreakdown.effectiveTaxRatePercent

(federalTax + ficaTax) / gross × 100.
comparisonDeltaAnnualTakeHome

compare-salary take-home − primary take-home.

Engine source: src/lib/salary-calculator/engine.ts

3. Formula / scoring logic

taxable_income = max(0, gross + other_income - pre_tax - standard_deduction)
federal_tax    = bracket_tax(taxable_income, filing_status)
fica           = min(gross, ssa_wage_base) * 0.062 + gross * 0.0145
take_home      = gross - federal_tax - fica

4. Assumptions

Uses 2026 US federal tax brackets and standard deduction (single $16,100 / married-joint $32,200) and the 2026 SSA wage base ($184,500).
There is NO state or local tax line — the tool is federal-only.
Assumes single-job W-2 income with the standard deduction, no dependents or credits.

5. Data sources

US IRS — federal tax brackets and standard deduction as of 2026
US SSA Social Security wage base as of 2026

6. Known limitations

Federal-only: no state, local, SDI, or SUI withholding is modeled.
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 the tool does not add the 0.9% Additional Medicare surtax above $200k single / $250k joint.

7. Reproducibility

Input
mode = annual, annual_salary = $100,000, filing_status = single, pre_tax_deductions_annual = $0.

Expected output
taxableIncome = $83,900, federalTax = $13,170, ficaTax = $7,650, estimatedTakeHomeAnnual = $79,180, monthly ≈ $6,598.33, effectiveTaxRatePercent = 20.82.

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: 68627.5
estimatedTakeHomeMonthly: 5718.96
estimatedTakeHomeBiweekly: 2639.52
overtimeAnnualGross: 0
taxBreakdown.taxableIncome: 68900
taxBreakdown.federalTax: 9870
taxBreakdown.ficaTax: 6502.5
taxBreakdown.effectiveTaxRatePercent: 19.26
taxBreakdown.standardDeduction: 16100
comparisonDeltaAnnualTakeHome: 7035
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]: Take-home nets federal income tax and employee FICA (Social Security 6.2% to the wage base + Medicare 1.45%); it excludes state/local taxes, the employer's payroll taxes, credits, and individualized deductions.

Frequently asked questions

What does the Salary / Paycheck Calculator calculate?: Converts gross pay to take-home using simplified US federal assumptions: federal income tax brackets plus employee-side FICA. It does not model any state or local tax. 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 6 inputs: mode (default annual), annual_salary, hourly_rate, filing_status (default single), pre_tax_deductions_annual (default 0), compare_annual_salary. Outputs returned: grossAnnual / grossMonthly / grossBiweekly, estimatedTakeHomeAnnual / Monthly / Biweekly, taxBreakdown.federalTax, taxBreakdown.ficaTax, taxBreakdown.effectiveTaxRatePercent, comparisonDeltaAnnualTakeHome.
What formula does the Salary / Paycheck Calculator use?: The exact computation is: taxable_income = max(0, gross + other_income - pre_tax - standard_deduction); federal_tax = bracket_tax(taxable_income, filing_status); fica = min(gross, ssa_wage_base) * 0.062 + gross * 0.0145; take_home = gross - federal_tax - fica
Can I verify the Salary / Paycheck Calculator with a worked example?: Yes. With mode = annual, annual_salary = $100,000, filing_status = single, pre_tax_deductions_annual = $0. the tool returns taxableIncome = $83,900, federalTax = $13,170, ficaTax = $7,650, estimatedTakeHomeAnnual = $79,180, monthly ≈ $6,598.33, effectiveTaxRatePercent = 20.82.
Where does the Salary / Paycheck Calculator get its benchmark data?: Reference data is sourced from: US IRS — federal tax brackets and standard deduction (as of 2026); US SSA Social Security wage base (as of 2026).
What can the Salary / Paycheck Calculator not tell me?: Known limitations: Federal-only: no state, local, SDI, or SUI withholding is modeled. 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 the tool does not add the 0.9% Additional Medicare surtax above $200k single / $250k joint.