Biweekly vs semimonthly pay

People treat “paid twice a month” as one thing. Payroll does not. Biweekly is every two weeks: 26 checks in a typical year, 27 in some calendars. Semimonthly is two checks a month on fixed dates (often the 15th and last business day): 24 checks, every year. The same salary produces different check sizes and a different federal line on this site because the annual wage is split by a different period count.

What this calculator does with frequency

If you type an annual salary, the paycheck calculator divides the annual federal tax and FICA by 52, 26, 24, or 12 depending on the button you picked. If you type a per-check amount, it multiplies first (×26 for biweekly, ×24 for semimonthly) and then taxes the implied year. Mixing those two is the usual mistake: pasting a biweekly stub amount while leaving the control on semimonthly invents a year that is too small, so federal tax looks light.

A worked example (illustrative)

Take $72,000 salary, single, no dependents, 2026 rules on this site. Annualize is already $72,000 either way. Subtract the $16,100 single standard deduction. Taxable is $55,900. Federal brackets apply to that year, then the annual tax is divided by 26 or by 24. The biweekly federal line is smaller per check; the semimonthly line is larger per check. Annual federal tax in this model is the same. FICA is 6.2% Social Security (under the wage base) plus 1.45% Medicare on the wages, also split by period count. The “take-home per check” changes. The “tax for the year” should not, except rounding.

What does change in real payroll is timing. A biweekly calendar sometimes has three checks in a month. Semimonthly does not. Those third checks still withhold. They are not a bonus and they are not extra salary. They are the 26th and 27th slices of the same year. If a friend says they get “two extra paychecks,” they usually mean two months with three biweekly deposits. Annual pay did not jump 8%.

Hourly and overtime

This site has no overtime field. A biweekly stub that includes 8 hours of overtime is not 1/26 of salary. If you want a closer federal estimate for a typical week, use a typical week’s gross × 26 (or 24), not the holiday week with overtime. Supplemental bonuses are often withheld at a flat rate; this calculator does not do that. See why a stub will not match.

What to enter

• Offer letter as annual salary: leave the amount on annual, pick the frequency you will actually be paid.
• A clean stub with no overtime: enter that check amount and the matching frequency.
• Two jobs: this page still treats one wage as the only wage. See two jobs and withholding.

Related: Form W-4 and federal withholding. Educational estimate, not payroll software.