Biweekly Paycheck Calculator

Twenty-six fortnights is 364 days, and the missing day is the whole story

A $65,000 salary paid every two weeks is $2,500.00 a cheque, twenty-six times. That is exact, and it is also the source of the only genuinely confusing thing about biweekly pay: twenty-six periods of fourteen days is 364 days. A calendar year has 365, or 366 in a leap year.

So a biweekly payroll cannot line up with the calendar. Each year its paydays slide one day later into the year, two in a leap year, until eventually a twenty-seventh payday is squeezed in before 31 December. Then the schedule resets and the drift starts again.

This is not an edge case and it is not a payroll error. The Office of Personnel Management, which administers federal biweekly pay under statute, says so flatly: “For some agencies, calendar year 1997 also contains 27 pay days instead of the usual 26. Over a period of several years, all agencies can expect to experience 27 pay days in a calendar year.”

Which years get twenty-seven, and why they are not your colleague's years

Work the calendar forward from a Friday payday and the answer is exact. It depends on which Friday your employer's schedule happens to land on, and there are two phases, so two people paid biweekly on a Friday by two different employers can be in different years from each other.

Friday paydays, counted off the 2026 calendar

Two things fall straight out of that table. The first is the interval: roughly eleven years, occasionally twelve. The second is what a twenty-seven-payday year looks like from the outside: a payday in the first two days of January and another in the last two of December. On the first schedule above, 2027 opens on Friday 1 January and closes on Friday 31 December, 364 days apart, which is twenty-six intervals and therefore twenty-seven paydays.

Neither 2026 schedule has twenty-seven. The first one ends its year on 18 December, so there is a thirteen-day gap with no payday in it before the year turns — which is a real cash-flow fact about late December 2026 even though nothing unusual is happening.

What the twenty-seventh cheque actually pays you

Here the two common pay frequencies part company completely, and federal pay law is the clearest place to see it, because it legislates both.

For biweekly pay, the rate is per period. OPM's guidance works it through on a real figure, a 1997 pay rate whose arithmetic is the point: a Senior Executive Service employee at the ES-5 level on an annual rate of $115,700 has an hourly rate of “$115,700 ÷ 2,087 hours = $55.44” and a biweekly rate of “$55.44 × 80 hours = $4,435.20”. Twenty-six of those is $115,315.20. Twenty-seven of them is $119,750.40. And the conclusion is the part nobody expects:

“The employee would be entitled to the full $119,750.40 earned in a calendar year with 27 pay days even though that amount exceeds the annual rate of $115,700.”

OPM states the general rule in one sentence beforehand: “Employees can actually receive more or less than their annual rate of basic pay in a given calendar year.” Note or less. In a twenty-six-payday year that same employee receives $115,315.20, which is $384.80 below the stated annual rate. The annual figure on the offer letter is a rate, not a promise about a calendar year.

Whether a private employer handles it the same way is a question for your employer, not for federal law. Two approaches exist in practice: pay twenty-seven cheques at the usual amount, so the calendar year's gross runs about 3.8% above the annual rate; or recalculate the per-period amount as the annual salary divided by twenty-seven, so each cheque shrinks and the year's total matches the salary. The first is what the rate-per-period logic above implies. The second is what a salary-as-annual-total reading implies. They produce noticeably different cheques, so it is worth asking which one you are on before the year starts.

What a twenty-seventh cheque does to your withholding

Federal withholding tables are built per pay period, and the number of periods is fixed in the method itself. Publication 15-T's worksheets carry a pay-periods table giving “Monthly: 12, Semimonthly: 24, Biweekly: 26, Weekly: 52, Daily: 260”, and the method then says to “Divide the amount on line 2g by the number of pay periods on line 1b” to reach the tentative withholding for the cheque. Biweekly is 26. The publication does not give an alternative figure for a year that contains twenty-seven paydays, and nothing in it tells an employer to recalculate.

So if you receive twenty-seven cheques and each one is withheld as one twenty-sixth of a year, the extra cheque is withheld at your average rate while the income it adds is taxed at your marginal rate. Those differ, and the gap lands on your return. Run $65,000 single through the estimate at the top of this page and the arithmetic is small but one-directional:

Each cheque withholds $216.15, which is correct for a twenty-six-cheque year and leaves the year about $184 short when a twenty-seventh arrives, because the extra $2,500 of wages crosses from the 12% band into the 22% one. It is not a disaster, and it is the right direction to know about: a twenty-seven-payday year makes a refund smaller or a bill larger, not the other way round. If that matters to you, Step 4(c) of the Form W-4 takes a flat extra amount per cheque, and the W-4 withholding estimator is the page for sizing it.

What it does to a percentage 401(k) deferral

A deferral set as a percentage of pay follows the cheques, and an extra cheque means an extra deferral. On a $65,000 salary a 10% election is $250.00 a cheque: $6,500 across twenty-six, $6,750 across twenty-seven.

That only becomes a problem near the annual limit. The IRS gives the 2026 elective deferral limit as “$24,500 in 2026, subject to cost-of-living adjustments”, with catch-up contributions of “$8,000 in 2026” from age 50 and $11,250 for ages 60 to 63. Someone aiming to hit $24,500 exactly by dividing it over twenty-six cheques defers $942.31 each time — and twenty-seven of those is $25,442.31, which is $942.31 over the limit. Plan administrators usually stop the deferral at the cap, but if you contribute to two plans in one year nobody is watching the total for you.

Twenty-four is not twenty-six minus two. It is a different kind of number

Semimonthly pay — the 1st and the 15th, or the 15th and the last day — is twenty-four cheques, and it never has a twenty-fifth, because it is anchored to months rather than to a fourteen-day cycle. Twelve months always contain twenty-four halves.

That difference is visible in statute. The same federal pay law that produces twenty-seven biweekly paydays treats monthly pay as a fraction of the year instead: OPM notes that “5 U.S.C. 5505 specifies that a month's pay is one-twelfth of a year's pay”, and that in twenty-seven-payday years “agencies must ensure that the basic pay earned in a calendar year by employees paid on a semi-monthly basis does not exceed 12 times their monthly rate of pay”. Biweekly pay is a rate per period that the calendar can hand you more of. Semimonthly pay is a slice of a fixed annual total that the calendar cannot change.

The wage regulations use the same split. 29 CFR 778.113(b) converts a semimonthly salary to a weekly wage “by multiplying by 24 and dividing by 52”, and a monthly salary “by multiplying by 12 (the number of months) and dividing by 52 (the number of weeks)”. Both start from a count of months. The biweekly figure never needs converting, because it already is a period rate.

On the same $65,000 the two schedules look like this, and the thing to notice is that the per-cheque gap is not a pay difference at all:

The $208.33 is the usual budgeting bug in both directions. Dividing a salary by 24 when you are actually paid 26 times overstates every cheque by 8.3%; dividing by 26 when you are paid semimonthly understates it by 7.7%. Neither changes the year.

Which schedule you are on is not always the employer's free choice, either. The Department of Labor keeps a table of state payday requirements listing each state's minimum pay frequency, and the entry worth knowing is the one with nothing in it: “Alabama and Florida. No regulations or not specified.”

Three-paycheck months, and the two in 2026

Because twenty-six paydays do not divide evenly into twelve months, two months a year carry three of them. Which two depends on the same schedule phase as the twenty-seventh payday. Counted off the 2026 calendar: a Friday schedule starting 2 January has three paydays in January and July 2026; one starting 9 January has three in May and October 2026. Every other month gets two.

No extra salary arrives in those months. Your annual pay is unchanged and the third cheque is withheld exactly like the other two. What changes is that your monthly outgoings — rent, a mortgage, insurance — are charged twelve times a year while your income arrives twenty-six times, so twice a year the two schedules happen to favour you. Budget on $5,416.67 a month, which is the honest monthly figure, rather than on two cheques of $2,500.00, which is $5,000.00 and understates ten months of the year.

What this calculator does not know

It cannot model twenty-seven paydays. The engine behind this page uses twenty-six biweekly periods and twenty-four semimonthly ones, with no field for a twenty-seventh. In a twenty-seven-payday year, read the per-cheque figures as correct and the annual totals as one cheque short.

Both net rows are built the same way. With a non-zero 401(k) percentage the biweekly row and the semimonthly row both take the deferral out of the cheque, so the two are directly comparable. At 10% on $65,000 the biweekly row reads $1,872.60 and the semimonthly row $2,028.65, a gap of $156.05. Until 3 October 2026 the semimonthly row left the deferral in, which reported that gap as $426.88 — nearly three times the real one, on the single row this page exists to show.

The annual net figure is built from the year's own components. Social Security stops for the year once year-to-date wages reach $184,500, and Additional Medicare Tax starts once they pass $200,000, so neither is level across the year and no single cheque multiplies out to one. The annual row charges Social Security on the base rather than on every dollar, and includes the Additional Medicare Tax a high earner owes. Until 3 October 2026 it multiplied the first cheque, which overstated Social Security by $3,441 and missed $360 of Additional Medicare Tax, a net $3,081 understatement of the year's take-home.

It does not know your pay dates. The twenty-seven-payday years and three-cheque months on this page were counted off the 2026 calendar from the two Friday schedules. If your payday is another weekday, or your employer anchors the schedule differently, count your own: list your paydays, add fourteen days repeatedly, and see where 31 December falls.

The state field is one flat percentage. No state levies income tax that way. Brackets, state deductions, local and county taxes, and states that do not tax wage income at all are all outside this estimate.

It is not withholding. The federal figure is a simplified annual calculation using the 2026 standard deduction and bracket thresholds, divided by the number of periods. It is not Publication 15-T, and it does not read your Form W-4: dependents, a second household income and extra withholding all move the real number.

Sources

• U.S. Office of Personnel Management, CPM 97-03: Guidance on Pay Caps in Calendar Years with 27 Pay Days — that all agencies can expect a 27-payday year, that employees may receive more or less than their annual rate in a calendar year, the ES-5 worked example at $115,700 giving $115,315.20 and $119,750.40, and the 5 U.S.C. 5505 rule that a month's pay is one-twelfth of a year's pay.
• U.S. Office of Personnel Management, Computing Hourly Rates of Pay Using the 2,087-Hour Divisor — the 2,087-hour divisor required by 5 U.S.C. 5504(b), which produces the $55.44 hourly rate in the example above.
• IRS Publication 15-T, Federal Income Tax Withholding Methods — the pay-periods table fixing biweekly at 26 and semimonthly at 24, and the instruction to divide the annual amount by that number of periods. Read on 2 October 2026: it gives no alternative figure for a year containing 27 paydays.
• IRS, Retirement topics — 401(k) and profit-sharing plan contribution limits — the $24,500 elective deferral limit for 2026, the $8,000 catch-up from age 50 and $11,250 for ages 60 to 63.
• 29 CFR 778.113, Salaried employees — general — converting semimonthly and monthly salaries to a weekly wage by multiplying by 24 or 12 and dividing by 52.
• U.S. Department of Labor, State Payday Requirements — the minimum pay frequency each state requires, and that Alabama and Florida specify none.
• IRS Publication 15 (Circular E), Employer's Tax Guide — the 6.2% Social Security rate, the $184,500 wage base and the 1.45% Medicare rate for 2026.
• IRS Topic no. 560, Additional Medicare Tax — the 0.9% rate and the $200,000 wage threshold at which an employer must begin withholding it.

Rates on this page were read against the sources above on 2 October 2026; the payday counts were computed from the 2026 calendar. The calculator runs in your browser and nothing you type is sent anywhere. More: the rest of the PaystubKit calculators.