Methodology

Every calculator on this site runs in your browser using published formulas. This page summarizes how they work and where our data comes from.

Loans and mortgages

Fixed-rate payments use the standard amortization formula M = P × r(1+r)ⁿ / ((1+r)ⁿ − 1) with a monthly rate r = annual rate ÷ 12. Amortization schedules apply interest to the remaining balance each month; the final payment is adjusted for rounding. The mortgage calculator adds property tax, insurance and HOA dues, and applies PMI only when the down payment is under 20%, removing it when the scheduled balance reaches 80% of the home price.

Savings and compound interest

Compound growth uses A = P(1 + r/k)^kt. Savings contributions are assumed at the end of each month.

Retirement accounts (2026 limits)

• 401(k): $24,500 elective-deferral limit; $8,000 catch-up at age 50+; $11,250 higher catch-up for ages 60–63 (SECURE 2.0); $72,000 Section 415(c) total additions limit. Sources: IRS IR-2025-111, IRS COLA table, IRS catch-up contributions.
• IRA / Roth IRA: $7,500 limit ($8,600 at age 50+, $1,100 catch-up). Roth MAGI phase-out: $153,000–$168,000 single/head of household, $242,000–$252,000 married filing jointly, $0–$10,000 married filing separately. Reduced amounts follow the IRS worksheet (round up to $10, $200 minimum). Sources: IRS IRA contribution limits, IRS IR-2025-111.
• Projections hold limits at 2026 levels, assume a constant return and salary growth, monthly contributions with monthly compounding, and full vesting. Balances are shown before taxes on withdrawal and in future (not inflation-adjusted) dollars.

Credit cards, student loans, CDs and inflation

• Credit card payoff: monthly interest at APR ÷ 12, no new charges or fees. The minimum-payment comparison uses interest + 1% of balance with a $25 floor (issuer formulas vary).
• Student loans: fixed-rate standard amortization; extra payments applied to principal. Income-driven plans, forgiveness and deferment are not modeled.
• CDs: APY = (1 + APR/n)ⁿ − 1; value = deposit × (1 + APY)^years; held to maturity with no penalties.
• Inflation: future cost = amount × (1 + i)^t, purchasing power = amount ÷ (1 + i)^t, at a rate you choose. No historical CPI data is embedded; for history use the BLS CPI Inflation Calculator.

Home buying, HELOCs and mortgage prepayment

• FHA loans: upfront MIP 1.75% of the base loan amount (financed); annual MIP from HUD Mortgagee Letter 2023-05 / Handbook 4000.1 Appendix 1.0 (e.g. 0.50% or 0.55% for terms over 15 years at base loans up to the national conforming limit; 11 years when LTV ≤ 90%, otherwise the loan term), charged on each year's average scheduled balance of the base loan (excluding financed UFMIP); the year-1 monthly figure is base loan × annual rate ÷ 12. The large-loan threshold uses the 2026 national conforming loan limit of $832,750 (FHFA). Minimum down payment 3.5% with a decision credit score of 580+, 10% with 500–579 (HUD). County FHA loan limits are not checked. Sources: HUD ML 2023-05 (PDF), HUD credit score / LTV rules (PDF), FHFA 2026 conforming loan limits.
• VA loans: purchase funding fee 2.15% (first use) / 3.3% (subsequent use) with under 5% down, 1.5% with 5%+, 1.25% with 10%+; exemptions as listed by VA. Rates effective April 7, 2023. Source: VA.gov funding fee and closing costs.
• Rent vs. buy: monthly simulation; property tax and maintenance as a % of current value, appreciation and investment returns compounded monthly, rent raised annually; the cheaper path invests the monthly difference; buyer equity is net of selling costs. Income taxes, PMI and the mortgage-interest deduction are not modeled.
• HELOC: max line = value × CLTV − mortgage; full draw at the start, interest-only during the draw period, then level amortization over the repayment period at a constant rate (real HELOC rates are usually variable).
• Extra mortgage payments: month-by-month simulation; yearly extras applied in months 12, 24, …; all extra payments applied to principal immediately with no prepayment penalty.

APR, simple interest, budgeting, net worth and percentages

• APR: the monthly rate that equates the net amount received (loan minus prepaid fees, or the full loan when fees are financed) with the present value of the payments, solved numerically and multiplied by 12 (actuarial method). Which fees count as finance charges under Regulation Z varies; Loan Estimate APRs may differ slightly.
• Simple interest: I = P × r × t with t in years (months ÷ 12, days ÷ 365).
• Budget: 50/30/20 split of take-home pay. Net worth: assets − liabilities as entered. Percentages: X% of Y = X/100 × Y; X/Y × 100; change = (new − old) ÷ |old| × 100.

Debt payoff

Debts are simulated month by month. The comparison tool rolls freed-up minimum payments to the next target (avalanche: highest rate first; snowball: smallest balance first).

Paycheck calculator (2026)

• Federal brackets and standard deduction: 2026 figures from IRS Revenue Procedure 2025-32 and the IRS announcement of 2026 inflation adjustments — standard deduction $16,100 (single), $32,200 (married filing jointly), $24,150 (head of household); rates 10%–37%. Sources: IRS newsroom, Rev. Proc. 2025-32 (PDF).
• Social Security: 6.2% on wages up to the 2026 wage base of $184,500. Source: SSA 2026 announcement.
• Medicare: 1.45% on all wages plus the 0.9% Additional Medicare Tax above $200,000 (single, head of household) or $250,000 (married filing jointly). These thresholds are set by statute and not indexed. Note: employers withhold the additional 0.9% once wages exceed $200,000 regardless of filing status; we estimate your actual liability.
• State taxes — flat/simple states with verified 2026 rules: for these states the calculator applies the official 2026 rate and, where noted, the state deduction/exemption or zero-tax threshold:
  • Georgia 4.99% flat (HB 463, retroactive to Jan 1, 2026), $15,000/$30,000 standard deduction — Georgia DOR
  • North Carolina 3.99% flat — NCDOR tax rate schedules (NC standard deduction $12,750 single / $25,500 joint / $19,125 HoH)
  • Montana 4.7% up to $47,500 (single) / $95,000 (joint) / $71,250 (HoH), 5.65% above, on federal taxable income — Montana DOR (HB 337)
  • Indiana 2.95% (county taxes not included) — Indiana DOR
  • Kentucky 3.5%, $3,360 standard deduction — Kentucky DOR
  • Mississippi 4.0% on taxable income above $10,000 — Mississippi DOR
  • Ohio $332 + 2.75% of nonbusiness income above $26,050 (personal exemptions not modeled) — Ohio Rev. Code 5747.02
  • Utah 4.45% with the taxpayer credit (see below) — Utah Code 59-10-104
  • Idaho 5.3% above $4,811 / $9,622 of taxable income — Idaho State Tax Commission
  • Illinois 4.95%, $2,925 exemption per person — Illinois DOR IL-700-T
  • Colorado 4.4% of federal taxable income — Colorado DOR DR 0104EP (2026)
  • Iowa 3.8% flat — Iowa DOR
  • Louisiana 3.0% flat — Louisiana DOR
  • Michigan 4.25% — Michigan Treasury
  • Arizona 2.5% of taxable income, as used in the 2026 estimated-tax worksheet — Arizona DOR Form 140ES (2026)
  • Pennsylvania 3.07% of compensation (401(k) deferrals are not deductible in PA) — statutory flat rate, confirmed by the Tax Foundation 2026 table
  Some deduction/exemption amounts (LA, MI, MS, NC) are taken from state guidance and secondary compilations and should be treated as approximate.
• No wage income tax (0%): Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington and Wyoming.
• Fully modeled graduated states (2026): standard deduction, personal/dependent exemptions or credits and brackets, from each state's official 2026 publication. The data table is in state-tax-2026.js.
  • California: FTB Tax News, 2026 Indexing (tax rate schedules X/Y/Z, standard deduction, exemption credits); EDD 2026 SDI rate 1.3%, all wages subject — Exemption-credit phase-out for high incomes and the renter's credit are not modeled.
  • New York: NYS DTF Form IT-2105-I (2026) rate schedules and standard deductions — NYC/Yonkers local income taxes are not included.
  • Oregon: Oregon DOR Withholding Tax Formulas 150-206-436 (2026) — Uses Oregon's official 2026 withholding formula values; head of household is treated as single, as in the withholding formula. Local transit/Metro/Multnomah taxes are not included.
  • Minnesota: MN DOR press release, 2026 brackets, standard deduction and dependent exemption — Standard-deduction/exemption phase-outs above $244,400 AGI and the refundable child credit are not modeled.
  • New Jersey: NJ Division of Taxation, Tax Rate Schedules (2020 and after) — NJ SDI/FLI/UI employee contributions are not included. NJ treats some pre-tax benefits differently from federal rules.
  • Virginia: Virginia Tax, Deductions (standard deduction $8,750/$17,500); Virginia Tax withholding formula (rates, $930 exemptions) — The higher standard deduction is scheduled to sunset after 2026.
  • District of Columbia: DC OTR income tax rates; DC OTR 2026 D-40ES (standard deductions)
  • Wisconsin: Wisconsin DOR 2026 Form 1-ES instructions (2026 standard deduction schedules and tax rate schedules) — sliding standard deduction and $700 exemptions modeled; Wisconsin income approximated by wages after pre-tax deductions; school property tax and itemized deduction credits not modeled.
  • Utah: Utah TC-40 (2026 draft, 9/28/26), lines 8–18; Utah Legislature 2026 Tax Credit Review
• Graduated states modeled from a compiled 2026 table: for these states the brackets, deductions and exemptions come from the Tax Foundation’s February 2026 compilation of state statutes, forms and instructions, with a link to each state’s revenue department. They have not yet been checked line by line against each state’s own 2026 publication, so treat them as close estimates.
  • Alabama: Alabama DOR individual income tax rates — Uses the minimum standard deduction ($2,500/$5,000), which applies above about $35,000 single / $60,000 joint AGI; lower incomes get up to $3,000/$8,500, so tax is slightly overstated there. Dependent exemption is $500 (AGI $50k-$100k; $1,000 below, $300 above). The deduction for federal income tax paid and local occupational taxes are not modeled.
  • Delaware: Delaware Division of Revenue, personal income tax rate schedule — Wilmington city wage tax is not included.
  • Kansas: Kansas DOR (SB 1, 2024 tax law changes) — Head-of-household standard deduction is from the 2024 law. Local intangibles taxes are not included.
  • Maryland: Comptroller of Maryland, tax rates (Budget Reconciliation and Financing Act of 2025) — State tax only. Exemption phase-outs above $100,000/$150,000 AGI are not modeled.
  • Massachusetts: Massachusetts DOR, personal income tax rates (4% surtax over the indexed threshold) — The PFML payroll contribution (0.46% employee share) and deductions for Social Security/Medicare and rent are not modeled. The 9% rate is the 5% base plus the 4% surtax; the $1,083,150 threshold is the 2025 figure (2026 indexing not yet published).
  • Missouri: Missouri DOR, 2026 withholding and tax rate chart — Missouri's deduction for federal income tax paid (limited for higher incomes) and Kansas City/St. Louis earnings taxes are not modeled.
  • Nebraska: Nebraska DOR, 2026 tax rate schedules (LB 754) — Head of household uses the joint brackets and an estimated $13,000 deduction (Nebraska's HoH schedule differs slightly).
  • New Mexico: New Mexico TRD, 2025+ rate tables (HB 252, 2024) — The $4,000 deduction applies to all dependents except one, as in New Mexico law. Low-income rebates and credits are not modeled.
  • North Dakota: North Dakota Office of State Tax Commissioner, income tax rates — Bracket thresholds are the latest published (indexed annually). HoH uses the single brackets here; North Dakota's HoH schedule is somewhat wider.
  • Oklahoma: Oklahoma Tax Commission (HB 2764, 2025) — Rates and brackets from HB 2764, effective Jan 1, 2026.
  • Rhode Island: Rhode Island Division of Taxation, 2026 tax rate schedule — Deduction and exemption phase-out ($261,000–$290,800 modified AGI) is not modeled. HoH standard deduction is estimated.
  • South Carolina: South Carolina DOR, individual income tax rates — Uses the 6% top rate in effect Jan 1–Jun 30, 2026; it is scheduled to revert to 6.2% on Jul 1, 2026, so tax may be slightly understated. Uses the pre-OBBBA federal standard deduction to which SC conforms ($8,350/$16,700); the dependent deduction is the 2025 figure.
  • West Virginia: West Virginia Tax Division (SB 2033, 2025 rate reduction) — Married filing separately uses half-width brackets in WV; here MFS uses the same brackets.
• Utah taxpayer credit: 6% × (federal standard deduction + $2,167 per dependent), reduced by 1.3% of Utah taxable income above $18,696 (single/MFS), $28,045 (HoH) or $37,392 (joint), per the 2026 TC-40.
• Child tax credit (2026): $2,200 per qualifying child, refundable portion up to $1,700 (15% of earnings above $2,500); $500 for other dependents; phase-out $50 per $1,000 of AGI above $200,000 ($400,000 joint). Source: IRS Rev. Proc. 2025-32. Married filing separately uses the 2026 MFS brackets (35% bracket ends at $384,350) and a $125,000 Additional Medicare threshold.
• Other states (graduated brackets, not yet modeled): AR, CT, HI, ME, VT. A single approximate flat rate is applied to wages after pre-tax deductions and the result is labeled “Estimate: brackets not yet modeled”. It ignores brackets, local income taxes (e.g. Maryland counties), state deductions and credits.
• Assumes the standard deduction, no tax credits, no other income, and that 401(k) deferrals reduce income-tax wages (but not FICA wages) while Section 125 health premiums reduce both.

Limitations

All results are estimates for educational use and are not financial or tax advice. See our terms. Last reviewed: October 19, 2026.