W-2 Wage Calculator: Calculate W-2 Wages From Your Pay Stub

What your final pay stub can (and can't) tell you about your W-2

Your last stub of the year carries the same year-to-date accumulators payroll feeds into your W-2, so the numbers are all sitting there. The catch is that a stub reports gross earnings and a W-2 reports taxable wages. Those are not the same thing. Getting from one to the other means adding the taxable fringe benefits that never hit gross pay, subtracting the cafeteria-plan items exempt from both income tax and FICA, and then subtracting your traditional retirement deferrals, in that order.

Because those subtractions happen in stages, one starting number ends up producing three different answers. That is why Box 1, Box 3, and Box 5 almost never match. Boxes 3 and 5 fall out of the second stage. Box 1 falls out of the third. The reconciliation ladder up top walks the same stages with your own numbers in them, so you can see where yours split apart.

Treat the result as an estimate. The W-2 your employer issues is the document of record, and plenty can move it after your last stub prints: imputed income posted in a year-end adjustment run, a manual correction, third-party sick pay reported by an insurer, a stub cutoff that falls on a different date than the pay date. Box 2 is a pass-through here. Federal withholding is the running total of a year of W-4 driven deductions, not something you can derive from wages. If that is the number that looks off, the mechanics of federal withholding explain where it comes from.

Which pre-tax deductions reduce which W-2 boxes

Most calculators dump every pre-tax deduction into a single field, which quietly hands anyone with a traditional 401(k) a wrong Box 3 and Box 5. The deductions really fall into three groups, and the group decides which boxes shrink:

• Federal income tax only: traditional 401(k), 403(b), and 457(b) deferrals, plus SIMPLE IRA contributions. They cut Box 1 and leave Boxes 3 and 5 untouched, so you still pay 6.2% Social Security and 1.45% Medicare on every dollar you defer. Source: IRS Pub. 15, Section 15.
• Federal income tax and FICA: Section 125 health, dental, and vision premiums, HSA contributions run through payroll, health FSA contributions, dependent care FSA up to the exclusion limit, and Section 132(f) commuter and parking benefits. They cut all three boxes. Source: IRS Pub. 15-B (2026), Cafeteria Plans and Transportation Benefits.
• Neither: Roth 401(k) contributions and post-tax garnishments. They come out of net pay and reduce nothing on the W-2.

The traffic runs the other way too. Employer-paid group-term life coverage above $50,000 creates imputed income under IRC Section 79, valued off the Uniform Premium Table I, and personal use of a company car is a taxable fringe benefit. Neither one shows up in gross earnings, and both add to Boxes 1, 3, and 5. Group-term life imputed income also lands in Box 12 with code C. If the Box 5 minus Box 1 gap is what brought you here, the 401(k) Paycheck Impact Calculator and our breakdown of the 401(k) impact on take-home pay work the same split from the paycheck side.

Why Box 3 stops at the Social Security wage base

Social Security tax only applies up to an annual wage base: $184,500 for 2026, up from $176,100 for 2025. At the 6.2% employee rate, Box 4 tops out at $11,439.00 for 2026. Medicare has no cap at all, so the moment your FICA wages clear the wage base, Box 3 freezes while Box 5 keeps climbing. That one rule is the most common reason a high earner gets a wrong answer out of a generic pay-stub converter. There is more on the timing in when Social Security tax stops.

The cap is per employer, not per person. Change jobs or work two of them and each employer restarts the count, so two W-2s can each show a full $184,500 in Box 3 and leave you over-withheld. You claim the excess back as a credit on Form 1040, Schedule 3. Nobody nets it out for you.

Above the cap, the 0.9% Additional Medicare Tax layers on top of Box 5. Your employer starts withholding it once your wages with that employer pass $200,000, flat, with no regard for how you file and no employer match. You settle up against your real filing-status threshold on Form 8959, which is where a married-filing-jointly couple with two sub-$200,000 salaries can find out they owe surtax nobody withheld. The employer half of FICA is covered in the employer FICA match explained.

How to check your W-2 against your pay stub before you file

The check itself is quick. Run your YTD numbers through the calculator, then compare the calculated Box 4 against 6.2% of Box 3 and the calculated Box 6 against 1.45% of Box 5 plus any surtax. Drop the FICA amounts actually withheld into the optional fields and the tool runs that comparison for you. A gap under a dollar is rounding drift: payroll rounds to the cent on every paycheck, and 26 of those roundings pile up over a year. Anything bigger is worth a question, though not an accusation. An off-cycle correction or a mid-year wage-base reset explains plenty of real gaps.

If the difference holds up, ask payroll for a corrected W-2c before you file, not after. Amending a return you have already filed is a lot slower than fixing the form. For the other side of the reconciliation, the Pay Stub Generator builds the YTD columns this tool reads, the Form 941 Quarterly Payroll Tax Calculator covers the employer-side quarterly totals that must foot to the annual W-2 and W-3, and the W-4 Paycheck Withholding Calculator is the obvious next step if Box 2 was the surprise.

If you would rather carry these wage bases forward next year than rebuild them from stubs, the WorkLogs44 Payroll Calculator app tracks per-employee year-to-date Social Security and Medicare wages as you run payroll, so the wage-base cap and the $200,000 surtax threshold get applied on the paycheck instead of discovered in January. One last reminder: this page gives you an estimate, your employer-issued W-2 is the document of record, and boxes 15 through 20 for state and local wages are out of scope here.