26 checks a year is not 24 checks a year
This is the reason most people arrive here, even if it is not what they typed. Somebody starts a job, the first check lands, and it is smaller than the last one at the old place on a salary that was supposed to be higher. Nothing is wrong and nobody is skimming.
Every two weeks is 26 checks a year. Twice a month is 24. Same annual money, cut differently, so each biweekly check is about 7.7% smaller than each semi-monthly one. Over the year the two land in exactly the same place. Two job offers quoting an identical salary can produce checks that look hundreds of dollars apart, and the difference is arithmetic rather than generosity.
The comparison above shows both on whatever figure you enter, because seeing them side by side is the only thing that settles it.
And the biweekly one gives you two odd months
Twenty-six does not divide into twelve. So if you are paid every two weeks, twice a year a calendar month holds three paydays rather than two.
That sounds like a bonus and it is not: it is your own money arriving in a lumpier pattern. What it actually breaks is monthly budgeting. Two checks a month is the right assumption for ten months of the year and understates the other two, which is why a rent-and-bills spreadsheet built on it drifts. People paid twice a month never meet this, because their dates are pinned to the month instead of to a two-week cycle.
The state is not a detail, it is most of the answer
A federal-only paycheck figure is wrong for most Americans, and wrong by thousands of dollars a year. Nine states take nothing at all from wages: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington and Wyoming. California tops out at 13.3% and Hawaii at 11%.
On the same salary that spread is a five-figure difference over a few years, and it is the single biggest thing missing from the calculators that hand you one number and no state selector. Washington deserves its footnote: it charges 7% on large capital gains and nothing on wages, so it behaves as a no-tax state for a salaried person and does not for somebody selling stock.
What a 401(k) does and does not reach
A traditional 401(k) or an HSA comes off your pay before federal and state income tax. It does not come off before Social Security and Medicare, which are charged on the pay you had before the deduction. So contributing more moves two lines on this page and leaves two exactly where they were.
That surprises people, and it is the same shape as a UK net-pay pension arrangement surprising somebody who expected National Insurance to fall with it. A Roth 401(k) reduces nothing today, because it is funded out of pay that has already been taxed.
Withholding is a guess. The bill is a fact.
Everything above is what comes off the check. What you owe is worked out once a year on your return, and the two only match by accident. A raise in July, a second job, a bonus withheld at a flat rate, or a W-4 you filled in for a life you no longer have all pull them apart.
A refund is not a windfall: it means you over-withheld and lent the government money for a year at no interest. A bill means the reverse. Line 4c of the W-4 lets you deliberately over-withhold, which is a reasonable way to avoid an April surprise as long as you know that is what it is.
Why this is its own page
There is a UK version of this on take-home pay and it is a different tool, not this one with the currency swapped. A British salary is annual and paid monthly, so the question there is what a rise or a pension change is worth, and the marginal rate is the headline. An American paycheck is biweekly or semi-monthly, so the question is what lands on Friday.
The deductions do not line up either: FICA, a state layer and a W-4 against PAYE, National Insurance and a tax code issued by HMRC. Neither is a translation of the other, and a single page covering both would carry half the fields nobody needs beside half the answers nobody asked for. Four separate pages is more work and it is the only version that is any use.
Fifty-one sets of figures, and where each one came from
Federal brackets, the standard deduction, the Social Security wage base and the FICA rates are from irs.gov and ssa.gov. State brackets, standard deductions and personal exemptions come from a consolidated table that cites the underlying statutes, which is a secondary source rather than fifty departments of revenue, and this page says so rather than implying otherwise.
Local and city income taxes are not included, and several cities levy their own. Neither are wage garnishments, union dues, insurance premiums or anything else your particular employer takes, because no calculator can know those. Your own stub is the authority on your own check; this page is for working out whether it looks right.
Common questions
Why is my biweekly check smaller than a friend's semi-monthly one on the same salary?
Because the same annual money is being cut into 26 pieces instead of 24. Every two weeks is 26 checks a year; twice a month is 24. On $78,000 that is roughly 7.7% less per check and exactly the same over the year. Nothing is being taken from you and nobody is underpaying you. It is the single most common reason somebody thinks a new job pays less than the offer said.
What is a three-paycheck month?
If you are paid every two weeks you get 26 checks a year, and 26 does not divide into 12. So twice a year a calendar month contains three paydays instead of two. Budgeting two checks a month is correct for ten months and understates two of them. People paid twice a month never get this: it is always exactly two, because the dates are fixed to the month rather than to a two-week cycle.
Does a 401(k) contribution reduce Social Security and Medicare?
No, and this is worth being clear about because half of the internet says otherwise. A traditional 401(k) or an HSA reduces income before federal and state income tax, which is why those lines move when you enter one. Social Security and Medicare are charged on pay before that deduction, so they do not move at all. A Roth 401(k) reduces nothing now, because it comes out of taxed pay.
Which states take nothing out of a paycheck?
Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington and Wyoming charge no income tax on wages. Washington is the one worth a footnote: it levies 7% on large capital gains and nothing on wages, so for a salaried person it behaves as a no-tax state and for somebody selling stock it does not. At the other end California tops out at 13.3% and Hawaii at 11%.
Is what comes off my check the same as what I owe?
Rarely exactly. Withholding is an estimate your employer makes from the W-4 you filed; the liability is settled on your return. A mid-year raise, a second job, a bonus withheld at a flat rate or a W-4 completed for a different situation all pull the two apart. A refund means you over-withheld and lent the money to the IRS interest-free for a year. A bill means you under-withheld.
What is W-4 line 4c for?
Extra withholding you ask for voluntarily, on top of what the tables produce. It lowers every check and comes back as a refund, so it is a savings account with the IRS as custodian and no interest. People use it to avoid an April bill, which is a reasonable thing to want, but it is worth knowing that is what it is rather than thinking of it as tax.
Why is there a separate page for this and not one calculator with a country switch?
Because a paycheck is not a translation of a British payslip. The unit is different: Americans are paid on a biweekly or semi-monthly schedule and ask what the check is, where a UK salary is annual and paid monthly. The deductions are different: FICA, a state layer and a W-4 against PAYE, National Insurance and a tax code. And the traps are different, which is most of the point. A page trying to cover both would carry half the fields nobody needs and half the answers nobody asked for.
Does anything I type here get sent anywhere?
No. The whole calculation runs in your browser. There is no account, nothing is uploaded and nothing is stored. Turn your network off and it still works, which is the easiest way to check that claim rather than take it on trust.