$51.00 an hour is how much a day?

$51/hour, a day

$408a day, before tax

$321 a day after federal tax and FICA · $106,080 a year

Before tax, a day$106,080 a year ÷ 260	$408
After tax, a dayfederal income tax and FICA only — no state tax	$321
A year, before tax51 × 2,080 hours	$106,080
A year, after tax21.3% withheld	$83,457
Federal income tax	−$14,508
Social Security + Medicare7.65% of wages	−$8,115
Per hour, after taxagainst $51 on paper	$40.12

Notes

$51 an hour is $408 a day before tax, working forty hours a week. The arithmetic is $106,080 a year divided across five days a week, fifty-two weeks.
260 working days is five days a week for all 52 weeks. Public holidays and time off come out of that, and whether they are paid decides whether the yearly figure holds.
After tax it is $321 a day. That is federal income tax of $14,508 and FICA of $8,115 over the year — 21.3% of gross, and it assumes no state income tax. Nine states take none; the rest take between about 2% and 9.3% more, so this figure is the ceiling rather than the average.
FICA is charged from the first dollar. Social Security takes 6.2% and Medicare 1.45%, with no standard deduction shielding either. Income tax does not start until after the $16,100 standard deduction, which is why the total bite at lower wages is mostly FICA rather than income tax.
Overtime is where this number actually moves. Hours past forty in a week are paid at $76.5 for non-exempt workers. Five overtime hours a week adds $19,890 a year — more than a 10% raise, for 12.5% more time.

The short answer

$51.00 an hour is $408 a day before tax, at forty hours a week — $321 after federal income tax and FICA.

Over a year that is $106,080 gross and $83,457 in hand, with 21.3% withheld.

Where it goes

Line	A year
Gross	$106,080
Federal income tax	−$14,508
Social Security + Medicare	−$8,115
Take-home	$83,457

This figure assumes no state income tax

Nine states take none: Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington and Wyoming. The other 41 take between roughly 2% and 9.3% at the top.

So $321 is a ceiling, not an average. The state-by-state figure has its own page.

FICA comes out of the first dollar

Social Security takes 6.2% of wages and Medicare 1.45%, with no standard deduction shielding either. Income tax does not begin until after the $16,100 standard deduction. At lower wages that makes FICA the larger of the two deductions — the opposite of what most people expect.

Overtime moves this more than a raise would

Hours past forty in a week are paid at $76.5 for non-exempt workers. Five overtime hours a week is $19,890 a year — more than a 10% raise, for 12.5% more time.

The threshold is forty hours in a week, not eighty in a fortnight. Fifty hours one week and thirty the next still earns ten hours of overtime, and an employer averaging across the pay period is getting it wrong.

Nearby sizes

$40 an Hour Is $83,200 a Year — Before Anything Comes OutThe multiply-by-2080 answer is the easy part. The number that matters is what survives federal tax, FICA and whatever the state takes.
How to Convert Salary to Hourly Rate: Divide by 2,080 — Then Divide by Real HoursDivide by 2,080 and you get the advertised hourly equivalent. Divide by the hours actually worked and you get the real one, and the two are rarely close.
$30 an Hour Is $62,400 a Year — About $49,000 After TaxSixty-two thousand four hundred. It is roughly the national mean for a carpenter, and comfortably above it for a roofer or a painter.
How Overtime Pay Is Calculated: 1.5× Over 40 Hours in a WeekTime and a half over forty hours in a week — federal law. The part that catches people is what counts as the regular rate, because it is not always the hourly rate on the offer.