How to Calculate Your Real Hourly Rate on a 24-Hour Shift Schedule

Two firefighters compare offers. Same title, same rank, salaries $2,000 apart. One department also runs Kelly days; the other doesn't. Neither number tells you who's actually paid more per hour worked — and "per hour worked" turns out to be a harder question on a 24-hour schedule than it sounds, because the answer depends entirely on which number you divide the salary by.

That's true anywhere a job pays an annual salary instead of an hourly wage, but it matters more on a 24-hour rotation than almost anywhere else, because the gap between "a standard year" and "your actual scheduled year" is enormous — hundreds of hours, not a rounding difference. Firefighters are the clearest example because the schedule and the hours are so well documented, but the same arithmetic applies to anyone paid a salary on a 24-hour duty cycle, such as EMS crews running 24s. If your job pays a salary against a 24-hour rotation rather than an hourly wage against a 40-hour week, this is your math too.

Here's the arithmetic, worked out in full, and where it stops being a personal budgeting exercise and starts touching an actual federal overtime rule.

Why the "hourly wage" on a job posting can already be wrong

Before getting to your own schedule, it's worth knowing why this trips up more than individual comparisons between two offers. Salary conversions often turn an annual figure into an hourly one using a flat 2,080-hour year — the standard 40-hour assumption. Applied to a salary on a 24-hour rotation, that produces a number that's meaningfully too high, because it assumes 2,080 scheduled hours where a straight 24/48 schedules 2,912. A posting that looks like it's advertising an unusually generous hourly wage for the role may just be an aggregator dividing by the wrong number, not a department paying above market. It's worth running the math yourself with your own department's actual annual-hours figure rather than trusting a hourly-rate conversion you didn't calculate.

The formula, and why the denominator is the whole problem

The idea is simple: effective hourly rate = annual salary ÷ annual scheduled hours. Anyone can do that division. The part that trips people up on a 24-hour schedule is the second number — annual scheduled hours isn't a fixed constant like it functionally is for a standard job. It depends entirely on which rotation you're actually on.

A 40-hour-a-week job scheduled for 52 weeks a year comes to a clean 2,080 hours (40 × 52), and almost nobody has to think about that number twice. A 24-hour rotation doesn't hand you a clean number for free — you have to work out what your own schedule actually adds up to before the division means anything.

What a 24-hour rotation actually adds up to

The building block on a 24/48 or 48/96 rotation is the same one covered in our firefighter shift schedules guide: one of three platoons is on duty at any time, which works out to being on duty one day in three.

• 24/48 — 24 hours on, 48 off, repeating every 3 days. That's 24 hours ÷ 3 days = 8 hours a day, averaged out, or 56 hours a week. Over 52 weeks: 56 × 52 = 2,912 hours a year.
• 48/96 — two 24-hour shifts, then 96 off, repeating every 6 days. Same ratio, same result: 48 hours ÷ 6 days = 8 hours a day averaged out, again 56 hours a week and 2,912 hours a year.

Both land on the identical annual figure, because both are built on the same one-in-three duty ratio — they just deliver those hours in different-sized blocks.

Where a lower number like 2,756 comes from

Not every department schedules a flat 56-hour week. Many build in Kelly days — scheduled shifts you don't work, dropped into the rotation to bring the average down — and we broke down the arithmetic behind them in a separate piece on the Kelly day. The short version: a department running a section 7(k) work period under the Fair Labor Standards Act has a maximum-hours standard of 212 hours per 28 days for fire protection employees before overtime is owed (29 CFR § 553.230). Convert that to a weekly figure: 212 ÷ 28 × 7 = 53 hours a week.

A department that schedules toward that 53-hour line rather than the raw 56-hour rate produces a different annual total: 53 × 52 = 2,756 hours a year — 156 hours less than a straight 24/48 with no Kelly days at all.

That is one reference point, not the only Kelly result. The cadence decides the number: a Kelly day on every seventh shift, for example, removes one shift in seven, so 2,912 × 6 ÷ 7 = 2,496 hours a year (48 hours a week). Your own total depends on how often your Kelly day actually lands.

That gap is exactly why "what's my annual salary supposed to cover" isn't a trivia question. A department can advertise the identical salary against either divisor, and the resulting "hourly rate" figure — the one that shows up in a recruiting flyer, a union comparison chart, or a mortgage pre-approval conversation — moves by real money depending on which one they picked.

The comparison table

Here's the same $75,000 hypothetical salary run through five different annual-hours figures, so you can see the size of the swing:

The same $75,000 reads as anywhere from about $25.76 to $36.06 an hour, purely as a function of the schedule attached to it — no change in take-home pay at all. That's the number worth checking before comparing two job offers. A "$36-an-hour job" on a 40-hour week and a "$75,000 firefighter job" on a straight 24/48 pay the same per year, but not the same per hour worked.

Worth double-checking your own arithmetic here rather than taking the table's word for it: 24 hours ÷ 3 days × 7 days confirms the 56-hour week, 212 ÷ 28 × 7 confirms 53, and each hourly figure divides back out to the $75,000 salary times its own hours column. If your department's actual duty-shift frequency or Kelly-day cadence differs even slightly, plug your own numbers into the same formula — the method matters more than any of these specific figures.

Running the formula the other direction

Sometimes the number you start with is a posted hourly rate rather than a salary — a department's pay scale might list "$26.50/hour" instead of an annual figure. The same formula runs in reverse: hourly rate × annual scheduled hours = annual salary.

Using the 24/48 figures above: $26.50 × 2,912 hours = $77,168 a year if that department schedules the full 56-hour week, or $26.50 × 2,756 hours = $73,034 a year if Kelly days bring the average down to 53. A gap of over $4,000 a year, from the same posted hourly rate, purely because of which annual-hours figure the department is quietly assuming behind it. If a pay scale or job posting gives you an hourly number without stating what annual-hours figure it's built on, that's a fair, specific question to ask before you compare it to anything else: "how many annual hours is that rate built on?"

This is not the same number as your legal "regular rate"

Everything above is a personal, informal calculation — useful for comparing job offers, understanding a salary, or filling out a loan application that asks for an hourly figure. It is a different question from the "regular rate" the Fair Labor Standards Act uses to calculate your actual overtime premium, and conflating the two is an easy mistake to make.

For a salaried employee generally, the regular hourly rate for FLSA purposes is computed by "dividing the salary by the number of hours which the salary is intended to compensate" (29 CFR § 778.113). For fire protection and law enforcement employees on a section 7(k) work period specifically, the regulations don't set a separate formula — they point back to that same Part 778 method: "the rules for computing an employee's 'regular rate' ... are set forth in part 778 of this title" (29 CFR § 553.233).

Two things make the legal version different from the comparison-shopping version above:

• "The number of hours the salary is intended to compensate" is a specific, documented figure your employer sets — it may or may not match the raw scheduled-hours arithmetic in the table above, and it's the number that actually controls your overtime math, not a general industry convention.
• The regular rate has to include more than base salary. Longevity pay, shift differential, certification or hazmat pay, and non-discretionary bonuses generally have to be folded into the regular rate calculation under Part 778's rules — none of which show up in a simple salary-divided-by-hours estimate done for comparison purposes.

If you need the legally correct regular rate — for a wage dispute, a union grievance, or checking a paycheck — that number comes from your payroll department or a wage-and-hour professional working from your actual pay records, not from the estimate above.

What to check before you trust any hourly figure

• What annual-hours figure is my salary actually built on? Ask HR or payroll directly rather than assuming 2,912 or 2,756 — plenty of departments use neither.
• Do I have Kelly days, and how often do they actually land? That's the difference between the two 24-hour-schedule rows in the table.
• Am I comparing this to another job's true annual hours, or to a lazy assumption of 2,080? A 12-hour-shift job and a 24-hour-shift job both look "full-time," but their annual-hours totals can sit roughly 570–730 hours apart (2,184 or 2,190 against 2,756 or 2,912).
• Am I trying to get a personal comparison number, or a number that has to hold up legally? Use the simple formula for the first; go to payroll for the second.

If you're weighing an offer between a 12-hour rotation and a 24-hour one, or trying to see what your own department's Kelly-day cadence actually does to your annual hours before you run the math above, the shift pattern calculator lays out 24/48, 48/96, and the Kelly cycle against real dates so you're counting from an actual calendar instead of an assumed average. Duty Pals is currently in pre-registration; you can sign up to be notified when it launches.

Sources: 29 CFR § 553.230 (maximum hours standards for 7(k) work periods), 29 CFR § 553.233 (regular rate for fire protection and law enforcement employees), and 29 CFR § 778.113 (regular rate for salaried employees generally).

General information about how annual scheduled hours are commonly calculated on 24-hour public-safety rotations, not legal, tax, or financial advice. The $75,000 figure above is a hypothetical used only to demonstrate the arithmetic. Whether your own salary is intended to compensate 2,912 hours, 2,756 hours, or some other figure — and what has to be folded into your actual FLSA regular rate — is set by your employer's pay records and, where applicable, your collective bargaining agreement. Consult your payroll department, HR, or a qualified wage-and-hour professional for anything you intend to rely on.

Related reading: Firefighter shift schedules: Kelly, 48/96, and 24/48 · The Kelly day, explained · FLSA 7(k) explained · The 4-on-4-off shift pattern explained