Hours Calculator

At its simplest, calculating hours between two times means subtracting the start time from the end time. If you clocked in at 9:00 AM and clocked out at 5:00 PM, that's 8 hours. Easy enough when the numbers are clean.

Things get a little trickier when you're dealing with odd minutes. Say you started at 8:45 AM and finished at 4:20 PM. You can't just subtract 8:45 from 4:20 straight up without converting to a common unit first. The cleanest approach is to convert both times to minutes since midnight, subtract, then convert back.

• 8:45 AM = (8 × 60) + 45 = 525 minutes
• 4:20 PM = (16 × 60) + 20 = 980 minutes
• 980 − 525 = 455 minutes
• 455 ÷ 60 = 7 hours 35 minutes

That's your total: 7 hours and 35 minutes worked. Converting to minutes first removes any confusion about borrowing across the colon.

The core formula is straightforward: Total Time = End Time − Start Time. When both times are on the same day and you're working in 24-hour (military) format, it's a clean subtraction.

For 12-hour AM/PM format, convert to 24-hour time first. Afternoon hours get 12 added to them: 3:00 PM becomes 15:00, 6:30 PM becomes 18:30, and so on. Midnight is 0:00 and noon is 12:00.

Stick to 24-hour format whenever you can. It eliminates AM/PM confusion and makes the subtraction much less error-prone, especially when you're doing it by hand.

Most workdays include at least one break, and those unpaid minutes need to come out of your total. The formula adjusts slightly: Total Work Hours = (End Time − Start Time) − Break Duration.

Say you work from 8:00 AM to 5:00 PM and take a 30-minute unpaid lunch. That's 9 hours on the clock minus 30 minutes, leaving you with 8.5 hours of actual paid time.

Multiple breaks work the same way. Just add up all break time and subtract the combined total.

• Shift: 7:00 AM to 4:00 PM = 9 hours
• Morning break: 15 minutes
• Lunch break: 30 minutes
• Total breaks: 45 minutes
• Net work time: 9 hrs − 0 hrs 45 min = 8 hrs 15 min

If your employer only counts unpaid breaks, make sure you're not subtracting paid rest periods. That distinction matters when you're calculating billable hours or verifying a paycheck.

Overnight shifts throw people off because the end time is numerically smaller than the start time. If you start at 10:00 PM and finish at 6:00 AM, a straight subtraction gives you a negative number, which obviously isn't right.

The fix is simple: add 24 hours to the end time before subtracting. So 6:00 AM becomes 30:00 (or 6 + 24 = 30), and then 30:00 − 22:00 = 8 hours.

Another reliable method is to split the shift at midnight. Count the hours from your start time to midnight, then count midnight to your end time, and add both together.

• 10:00 PM to midnight = 2 hours
• Midnight to 6:00 AM = 6 hours
• Total: 2 + 6 = 8 hours

Both methods get you to the same answer. Use whichever clicks more naturally for you. The split-at-midnight approach tends to be easier to do in your head without a calculator handy.

Payroll systems, invoicing software, and spreadsheets almost always want hours in decimal format rather than hours-and-minutes. Converting is pretty painless once you know the move.

Take the minutes portion of your time, divide by 60, and add it to your whole hours. That's it.

• 7 hours 30 minutes: 30 ÷ 60 = 0.5 → 7.5 hours
• 8 hours 15 minutes: 15 ÷ 60 = 0.25 → 8.25 hours
• 6 hours 45 minutes: 45 ÷ 60 = 0.75 → 6.75 hours
• 9 hours 20 minutes: 20 ÷ 60 ≈ 0.333 → 9.33 hours

Going the other direction works just as easily. Multiply the decimal portion by 60 to get back to minutes. So 8.25 hours: 0.25 × 60 = 15 minutes, giving you 8 hours and 15 minutes.

Decimal hours are especially useful when you're multiplying by an hourly rate. Multiplying 8.25 by your wage is a lot cleaner than trying to do it with hours and minutes separately.

Sometimes you end up with a raw count of minutes and need to express it as hours. The conversion is always the same: divide by 60.

If you worked 135 minutes, that's 135 ÷ 60 = 2.25 hours, or 2 hours and 15 minutes. To find the remaining minutes after the whole-hour portion, use the remainder: 135 ÷ 60 = 2 remainder 15, so 2 hours 15 minutes.

This comes up a lot when you're pulling data from apps or timers that log everything in minutes. One quick division and you're in a format that's actually usable.

Calculating your weekly hours is really just an extension of the daily math. Add up your net work hours for each day, then total them across the week. Simple in theory, though keeping track of different shift lengths and break times each day can get messy fast.

A daily log helps a lot. Jot down your start time, end time, and total break time each day, calculate the net hours, and then sum those at the end of the week.

In the US, any hours over 40 in a workweek typically qualify for overtime pay at 1.5 times your regular rate, under federal law. Knowing your weekly total accurately can mean real money, so it's worth being precise rather than estimating.

Getting your hours right isn't just a clerical nicety. For hourly workers, a miscalculation can directly affect your paycheck. For freelancers and contractors, it affects your invoices and, by extension, your income. Even salaried employees tracking overtime or flex time need accurate numbers to back up any claims or requests.

Employers and payroll departments rely on accurate time records too. Consistent errors, even small ones, add up over a year. Fifteen minutes off per day across a five-day workweek is over 60 hours annually. That's not a rounding error, that's a real discrepancy.

There's also a legal angle. The Fair Labor Standards Act (FLSA) requires employers to keep accurate records of hours worked. If a dispute ever comes up about wages or overtime, your own documented records are your best protection.

Beyond money and compliance, accurate time tracking helps you understand where your hours actually go. Whether you're managing a team, running a business, or just trying to maintain a better work-life balance, good data makes better decisions possible.