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NetPay Atlas
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2026 withholding · 130 same-input comparisons

How accurate is this paycheck calculator? 2026 test results

Every published number below is recomputed from our saved test data each time the site is built, so the page cannot drift from the calculator.

In short

NetPay Atlas is a free 2026 paycheck calculator that runs in your browser with no signup. To check it, we entered 130 identical paychecks — 12 states and cities, salaries from $30,000 to $500,000, four pay frequencies, three filing statuses, 27 with a 401(k) — into NetPay Atlas and PaycheckCity. The largest net-pay difference was $0.09 per paycheck (California); everywhere else it was $0.01 or less. Agreement between two tools is not a guarantee that either matches your employer's payroll.

130
same-input comparison cases
12
states and cities tested
$0.09
largest net-pay difference
2026
tax year (check date 2026-03-13)

Results by state

Per-paycheck differences between NetPay Atlas and PaycheckCity for the same inputs. “Largest tax-line difference” is the biggest gap on any single line: federal income tax, Social Security, Medicare, state tax or city tax.

JurisdictionCasesWith 401(k)Largest net-pay differenceLargest tax-line difference
California205$0.09$0.09
Florida102$0.00$0.00
Texas102$0.00$0.00
Nevada102$0.00$0.00
Washington102$0.01$0.00
Illinois102$0.00$0.00
New York State102$0.00$0.00
New York City102$0.00$0.00
Virginia102$0.01$0.01
Missouri102$0.00$0.00
North Carolina102$0.00$0.00
Georgia102$0.00$0.00

How the comparison was run

  • Same inputs on both sides: 2026 check date 2026-03-13, Form W-4 (2020 or later) with no Step 2, no dependents and no extra withholding, zero year-to-date wages, the state allowance shown in each case, and a traditional 401(k) where listed.
  • Spread of cases: salaries $30,000–$500,000; weekly, biweekly, semimonthly and monthly pay; single, married filing jointly and head of household.
  • Checked line by line: federal income tax, Social Security, Medicare, state income tax, city tax (NYC) and net pay — not only the final number.
  • One documented adjustment (11 cases): in PaycheckCity a single “exempt from state” box both removes a 401(k) from state income tax and from state payroll premiums (CA SDI, NY disability and Paid Family Leave, WA Cares and PFML). The state rules keep those premiums on full gross wages, so for 401(k) cases we compare with PaycheckCity's rerun on full gross.
  • Saved and repeatable: the inputs and PaycheckCity outputs are stored in our test suite and rechecked on every build; a test fails if any line moves by $1 or more.

Tests against official worked examples

Matching another calculator cannot catch a mistake both share, so the same suite also checks the government's own published numbers:

  • 66 IRS Publication 15-T (2026) wage-bracket values across four pay frequencies, filing statuses and the Step 2 checkbox.
  • All six California EDD Method B worked examples (A–F).
  • 15 New York worked examples from the 2026 NYS-50-T publications (state, New York City and Yonkers).
  • The published Virginia, Missouri, North Carolina, Georgia and Massachusetts examples, the Illinois IL-700-T formula and Social Security wage-base behavior.

What an accurate paycheck calculator has to handle

  • 2026 federal withholding with Form W-4 Steps 2, 3 and 4(a)–(c).
  • The state's own form: California DE 4, New York IT-2104, IL-W-4, VA-4, NC-4, G-4, MO W-4.
  • FICA: Social Security 6.2% up to $184,500, Medicare 1.45% plus 0.9% above $200,000.
  • State payroll premiums: CA SDI 1.3% with no wage cap, NY disability and Paid Family Leave, WA Cares and Paid Family & Medical Leave.
  • Pre-tax deductions treated correctly: 401(k) skips income tax but not FICA or SDI; California taxes HSA contributions; health, dental and vision premiums.
  • Pay frequency and pay type: weekly, biweekly (26), semimonthly (24) or monthly; salary or hourly with overtime.

Which calculator to use when

  • NetPay Atlas — a quick, private estimate with every tax on its own line, no signup, and published test cases. It does not take year-to-date wages yet.
  • PaycheckCity — detailed per-paycheck inputs such as pay date and year-to-date wages; the reference we compare against.
  • Payroll-provider calculators (ADP, Gusto, OnPay) — a useful second opinion; each says its result is an estimate.
  • IRS Tax Withholding Estimator — the official tool for checking your whole-year federal withholding and filling in a new W-4; it is not a full take-home-pay calculator.

For the closest match to a real pay stub, enter the same pay frequency, W-4, state form and pre-tax deductions your employer uses. Start with the California, New York (incl. NYC), Texas or any-state calculator. Full formulas are on the methodology page.

Frequently asked questions

Which free paycheck calculator is the most accurate?+

No public calculator can promise to match every employer's payroll, and a ranking without same-input tests is only a feature comparison. What you can check is whether a tool uses the 2026 official withholding methods and publishes its tests. NetPay Atlas uses IRS Publication 15-T and each state's published method, and on 130 identical inputs its net pay was within $0.09 of PaycheckCity. That shows the two tools agree; it does not prove either one matches your pay stub.

Why do ADP, PaycheckCity and SmartAsset show different take-home pay?+

Usually because the inputs are not the same: pay date and tax year, pay frequency, W-4 steps, the state form (DE 4, IT-2104 and so on), whether 401(k) or health premiums are pre-tax, year-to-date wages and whether a city tax applies. Rounding rules add a few cents. Enter identical inputs before comparing tools.

Is there a free paycheck calculator with no signup, no email and no ads?+

NetPay Atlas needs no account and no email, shows no ads inside the calculator, and runs the math in your browser — your salary is not sent to a server. It covers Form W-4 Steps 2–4, traditional and Roth 401(k), HSA and health, dental and vision premiums. The site uses Google Analytics for page views, as described in the privacy policy.

Does the calculator use 2026 tax tables?+

Yes. Federal withholding uses the 2026 Publication 15-T percentage method; Social Security is 6.2% up to $184,500; state formulas come from each state's 2026 employer guide, listed in the sources below.

What does this test not cover?+

Year-to-date wages from earlier paychecks, pre-2020 Forms W-4, bonuses inside a regular paycheck (we have a separate bonus calculator), employer-specific benefits and local taxes outside New York City and Yonkers. It also cannot detect a mistake that both calculators share — that is why we test against official worked examples too.

Is NetPay Atlas affiliated with PaycheckCity?+

No. NetPay Atlas is independent. We use PaycheckCity's free public calculator as a second, widely used reference and record its outputs with the inputs we entered.

Last reviewed 2026-10-09 by the NetPay Atlas team.