How each calculator works.

Paycheck Calculator

Take-home pay = gross pay − federal income tax − state income tax − Social Security (6.2%) − Medicare (1.45%) − any pre-tax deductions (401k, HSA, health premiums).

Federal income tax

Calculated using progressive brackets from IRS Rev Proc 2025-32 (the 2026 inflation-adjustment publication). Standard deductions for 2026are $16,100 (single), $32,200 (married filing jointly), and $24,150 (head of household). These are subtracted before bracket math. Each portion of taxable income is then taxed at its bracket's marginal rate.

FICA (Social Security and Medicare)

Social Security: 6.2% on wages up to the 2026 wage base ($184,500). Medicare: 1.45% on all wages. Additional Medicare Tax: 0.9% on wages over $200,000 (single) or $250,000 (married filing jointly). Source: SSA Cost-of-Living Adjustment publication.

State tax

For each state we use that state's actual tax structure — flat rate, progressive brackets, or zero — sourced from each state revenue department's official publications. The 9 no-income-tax states (TX, FL, TN, NV, WY, SD, AK, WA, NH) return $0 in state tax.

Known limitations

• Does not include local/city income tax (NYC, Philly, San Francisco, Detroit, etc.)
• Does not include state-specific additions like California SDI
• Does not apply tax credits (Child Tax Credit, EITC, etc.)
• Computes actual tax owed, not employer withholding (which can differ based on W-4)

1099 Tax Calculator

Self-employment tax = (gross income − expenses) × 0.9235 × 15.3%, with the Social Security portion (12.4%) capped at the SS wage base. Federal income tax is then calculated on (net profit − half-SE tax deduction − QBI deduction − standard deduction) using the same brackets as the paycheck calculator.

QBI (Qualified Business Income) deduction is the simplified 20% of net business income for filers below the phase-out threshold. Above the threshold our calculator applies a tapered deduction; for exact figures (especially for SSTBs like consulting and law) consult a CPA.

401(k) Calculator

Standard compound-growth model: each year, balance grows by (start_balance + contributions/2) × return_rate, approximating contributions made evenly through the year. Employer match is calculated as min(match_percent, cap_percent) × salary.

The model uses constant nominal dollars — it does not adjust for inflation. To convert future dollars to today's purchasing power, mentally apply ~3% annual inflation.

Mortgage Calculator

Standard fixed-rate amortization formula: Monthly P&I = (Loan × Monthly Rate × (1 + Monthly Rate)^N) / ((1 + Monthly Rate)^N − 1), where N is the total number of payments.

PITI breakdown: P&I from amortization, T from property tax %, I from annual home insurance / 12. PMI auto-applied at 0.5% of loan amount per year when down payment is below 20% (real PMI varies 0.3-1.5% based on credit score and LTV).

Social Security Calculator

Simplified estimate. The official SSA calculation requires your full 35-year wage history indexed for inflation. Our calculator approximates AIME (Average Indexed Monthly Earnings) from your recent income, then applies the standard SSA bend-points formula and claim-age adjustments.

• AIME ≈ min(annual income, SS wage base) / 12
• PIA = 90% × first $1,286 + 32% × next $6,463 + 15% above (2026 bend points from SSA)
• Age 62: 70% of PIA. Age 67 (FRA): 100% of PIA. Age 70: 124% of PIA
• COLA: 2.5% per year applied to lifetime totals when toggle is on (2026 SSA-announced rate)

For your exact projected benefit, log into ssa.gov/myaccount — the official portal shows your real benefit estimate based on actual SSA records.

Student Loan Calculator

Standard plan: same amortization formula as the mortgage calculator. Graduated plan: payments ramp linearly from ~60% of standard to ~150% over the term. Income-Based Repayment (IBR): 10% of monthly discretionary income, with forgiveness at 25 years (taxable as ordinary income).

Note: the SAVE plan replaced REPAYE for most borrowers, with rules continuing to evolve. Federal loan rules change; check studentaid.gov for current plan availability.

AI Summaries

Each calculator's plain-English summary is generated by Claude (Anthropic's AI), constrained by a strict system prompt: 3-5 sentences, no advice (never "you should" or "we recommend"), no jargon, always ending with the disclaimer line. Same inputs produce the same cached summary, ensuring consistency. If the AI is unreachable, a deterministic template fallback runs in its place.

What this site does NOT do

• Provide individualized financial, tax, or legal advice
• Account for tax credits (Child Tax Credit, EITC, AOTC, etc.)
• Account for AMT (Alternative Minimum Tax) — applies to a small number of high earners
• Account for capital gains separately from ordinary income
• Predict actual investment returns — projections use your input assumption