How to Calculate Work Hours: A Simple Guide

Knowing how to calculate work hours sounds simple — but between unpaid breaks, overnight shifts, decimal conversions, and overtime rules, the math gets complicated fast. One wrong entry on a timesheet can mean an underpaid employee, a compliance issue, or both.

This guide walks you through the exact steps to calculate work hours accurately — from recording clock-in times to converting minutes to decimals to getting the right number into payroll every time.

How to calculate work hours: The basics

Calculating work hours accurately means more than just subtracting a clock-in time from a clock-out time. The details — breaks, decimals, overtime, off-the-clock work — are where most payroll errors come from.

1. Subtract clock-out time from clock-in time to get gross hours worked
2. Subtract any unpaid breaks of 30 minutes or more where the employee was fully relieved of duties
3. Divide remaining minutes by 60 to convert to decimals — payroll systems don't read hours and minutes
4. Add up daily decimal totals for the week — anything over 40 hours triggers overtime under federal law
5. Repeat for every employee, every pay period, or let a time clock app do it automatically

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What counts as "hours worked"?

Before you start calculating, it helps to know what you're actually counting — because not every minute an employee is on the clock is a minute you owe them for, and not every minute off the clock is a minute you don't.

The Fair Labor Standards Act (FLSA) draws the line at duty. If an employee is required to be there and working — or available to work — that time counts. The key wrinkle is what the DOL calls the "suffered or permitted" standard: if you know an employee is working, those hours count even if you didn't ask them to. Pre-shift prep, post-shift cleanup, and working through lunch all go on the timesheet if you're aware it's happening.

What counts as hours worked:

• All time on duty, including slow periods
• Short rest breaks of 20 minutes or less
• Waiting time when an employee is "engaged to wait" (on-call and restricted to the workplace)
• Required training and meetings
• Travel time between job sites during the workday

What doesn't count:

• Regular commuting to and from work
• Bona fide meal breaks of 30 minutes or more — but only if the employee is completely relieved of all duties
• Voluntary participation in activities outside work hours
• On-call time where the employee is free to use the time for their own purposes

How to calculate work hours step by step

Here's the full process for calculating work hours manually, using a real example throughout.

Step 1 — Record your start and end times

Write down the exact clock-in and clock-out times for each shift. Precision matters here — rounding at this stage compounds errors later. For this example, we'll use an employee who clocked in at 8:47 AM and clocked out at 5:22 PM.

Step 2 — Convert to 24-hour (military) time

Converting to 24-hour time makes the subtraction in the next step straightforward. Add 12 to any PM time. Morning times stay the same.

• 8:47 AM = 8:47
• 5:22 PM = 17:22
• Quick reference: noon = 12:00 | 1 PM = 13:00 | 5 PM = 17:00 | 9 PM = 21:00

Step 3 — Subtract start time from end time

Subtract the clock-in time from the clock-out time.

17:22 − 8:47

Start with hours: 17 − 8 = 9 hours. Then minutes: 22 − 47 doesn't work, so borrow one hour from the 9. That gives you 8 hours and 82 minutes. Now subtract: 82 − 47 = 35 minutes.

Gross hours worked: 8 hours 35 minutes

Step 4 — Subtract unpaid breaks

If the employee took a 30-minute unpaid lunch break where they were fully relieved of duties, subtract it now.

8 hours 35 minutes − 30 minutes = 8 hours 5 minutes

Only subtract breaks where the employee had no work responsibilities. If they answered a call or handled a customer during that time, the break is compensable and stays in the total.

Step 5 — Convert minutes to decimal hours

Most payroll systems don't accept "8 hours and 5 minutes" — they need a decimal. Divide the remaining minutes by 60.

5 ÷ 60 = 0.08

Net hours worked: 8.08 hours

Use the conversion chart in the next section to speed this up for common minute values.

Step 6 — Add up daily totals for the week

Repeat steps 1 through 5 for each day, then add the daily decimal totals together. That weekly sum is what you need to calculate hours worked for the full pay period and determine whether overtime applies. Anything over 40 hours in a workweek triggers overtime under federal law.

Doing this math for five employees every week adds up fast. Let Homebase handle it — free time clock that tracks hours, breaks, and overtime automatically.

How to calculate hours and minutes: Decimal conversion chart

Payroll systems run on decimal hours. "8 hours and 35 minutes" needs to become 8.58 before it means anything to your payroll software. The formula is simple: minutes ÷ 60 = decimal hours. Or use this list as a quick reference.

• 5 min = 0.08 | 35 min = 0.58
• 10 min = 0.17 | 40 min = 0.67
• 15 min = 0.25 | 45 min = 0.75
• 20 min = 0.33 | 50 min = 0.83
• 25 min = 0.42 | 55 min = 0.92
• 30 min = 0.50 | 60 min = 1.00

Bookmark this section or keep it next to your timesheets. It'll save you from reaching for a calculator every time you hit an odd minute value. You can also use Homebase's free time card calculator to do the conversion automatically.

How to calculate work hours with a lunch break

Lunch breaks are one of the most common sources of payroll errors — not because the math is hard, but because the rules are easy to misapply.

Under the FLSA, a meal break of 30 minutes or more is unpaid only if the employee is completely relieved of all work duties for the full duration. That means no answering phones, no watching the register, no handling customer questions. If any work happens during the break, the entire period becomes compensable time.

Short breaks of 20 minutes or less are always paid. Don't subtract them from the total.

Worked example:

An employee works 7:00 AM to 3:30 PM with a 30-minute unpaid lunch at noon.

• Convert: 7:00 and 15:30
• Subtract: 15:30 − 7:00 = 8 hours 30 minutes = 8.50 hours gross
• Subtract lunch: 8.50 − 0.50 = 8.00 hours net

If that employee had taken a call during lunch and handled a customer issue, you'd owe them 8.50 hours instead — a difference that compounds quickly across a full team.

How to calculate work hours for payroll

Everything in the step-by-step section above is building toward this: getting hours into a format your payroll system can use. To calculate payroll hours correctly, you need decimal values — not hours-and-minutes. Once you've done the conversion, the gross pay calculation is straightforward.

How to calculate payroll hours and gross pay

Once you have your decimal hours, you're ready to calculate payroll hours and convert them into gross wages. This is the step where time tracking meets pay — and where a single decimal error can mean an under- or overpaid employee.

Gross pay formula: Decimal hours × Hourly rate = Gross wages

Using our example: 8.08 hours × $17.00/hour = $137.36

A few edge cases to watch for:

• Multi-rate employees: If someone works two roles at different pay rates in the same week, calculate each rate's hours separately, then multiply each by its respective rate before adding the totals together
• Overtime hours: Regular hours and overtime hours are calculated at different rates — don't blend them into one figure (more on this in the next section)
• PTO and holidays: Paid time off counts toward total compensation but typically doesn't count toward the 40-hour overtime threshold under federal law — check your state's rules at the DOL state labor offices directory
• Tip credits: If you take a tip credit, ensure tipped employees still reach minimum wage when tips are factored in, and that tip credit hours are tracked separately

Manual payroll math is where errors live — a misplaced decimal, a forgotten break, a missed overtime trigger. The right payroll tool calculates hours, overtime, and gross pay automatically so your numbers are right before your team gets their paychecks.

How to calculate overtime hours

Federal law under the FLSA requires overtime pay for any hours worked over 40 in a single workweek, at a rate of at least 1.5 times the employee's regular rate of pay. A few details that matter:

• A workweek is any fixed, recurring period of 168 hours — seven consecutive 24-hour periods. It can start on any day you choose, but once set, it needs to stay consistent
• You cannot average hours across workweeks. If an employee works 35 hours one week and 45 the next, the 45-hour week triggers 5 hours of overtime. The 35-hour week doesn't cancel it out
• Overtime cannot be waived by agreement between you and the employee — it's a legal requirement, not a negotiable term

Worked example:

An employee works 44 hours in a week at $15.00/hour.

• Regular pay: 40 hours × $15.00 = $600.00
• Overtime pay: 4 hours × ($15.00 × 1.5) = 4 × $22.50 = $90.00
• Total gross pay: $690.00

State overtime rules to watch for

Federal law only requires overtime after 40 hours in a workweek — but several states go further and can trigger premium pay before your employee even hits 40 hours for the week:

• California: Overtime after 8 hours in a day; double time after 12 hours in a day or after 8 hours on the seventh consecutive day of the workweek
• Alaska: Overtime after 8 hours in a day and after 40 hours in a week
• Colorado: Overtime after 40 hours in a week, 12 hours in a day, or 12 consecutive hours — whichever results in higher pay
• Nevada: Overtime after 8 hours in a day for employees earning less than 1.5 times the state minimum wage

If you operate in any of these states, run the calculation against all applicable thresholds and pay whichever produces the higher result. For your state's specific rules, the DOL state labor offices directory is the place to start. For federal overtime requirements, DOL Fact Sheet #23 is the authoritative reference. 

You can also use Homebase's free overtime calculator to run the numbers quickly.

When to stop calculating work hours by hand

Manual calculation works. For a small team with consistent schedules and simple pay structures, a spreadsheet and this guide will get you through. But the bigger your team gets, the harder it is to calculate work hours accurately every pay period without something slipping through.

Signs it's time to switch to a time tracking app:

• You're spending more than 30 minutes on timesheets each pay period
• You've found errors in a paycheck after it was already processed
• You have employees who regularly work overtime or irregular hours
• Your team works variable shifts, split shifts, or roles with different pay rates
• You've added employees and the manual process hasn't scaled with the headcount

A time clock app handles every step covered in this guide automatically. Employees clock in and out from their phones, breaks are tracked in real time, minutes are converted to decimals, overtime is flagged before it hits payroll, and hours export directly to your payroll system. No spreadsheets, no calculators, no Sunday-night math.

Every hour you spend on manual timesheets is an hour you're not running your business. Homebase's free time clock automates the math, catches overtime before it hits payroll, and keeps your team’s work hours on track.

Common work hours calculation mistakes (and how to avoid them)

Most payroll errors aren't careless — they're systematic. The same mistakes happen week after week because calculating work hours manually leaves too much room for misremembering the rules. Here are the six most common ones.

1. Forgetting to subtract unpaid breaks. If you're not tracking breaks separately, they blend into the total and inflate gross hours. Build break recording into your time tracking process from the start, not as an afterthought at payroll time.
   
   
2. Rounding inconsistently. The DOL permits rounding to the nearest 5 minutes, 6 minutes (one-tenth of an hour), or 15 minutes — but the rounding must be neutral over time, meaning it should average out in the employee's favor as often as the employer's. Always rounding down to the nearest quarter-hour violates the FLSA, even if the amounts per shift seem small.
   
   
3. Miscounting overnight shifts. A shift that runs from 10:00 PM to 6:00 AM isn't negative math — it just crosses midnight. Add 24 to the end time: 30:00 − 22:00 = 8.00 hours. Simple once you know the trick, but easy to get wrong the first time.
   
   
4. Averaging hours across workweeks. Each workweek stands alone under the FLSA. You can't offset a 45-hour week against a 35-hour week and call it even. Overtime is owed in the week it was worked, regardless of what happened the week before or after.
   
   
5. Missing off-the-clock work. Pre-shift setup, post-shift cleanup, and working through a lunch break all count as hours worked if you know about them. "I didn't ask them to do that" isn't a defense if you were aware it was happening.
   
   
6. Ignoring state daily overtime rules. If you're only running a 40-hour weekly check and you operate in California, Alaska, Colorado, or Nevada, you may be missing daily overtime triggers entirely. Run both calculations every week.

Track work hours automatically with Homebase

Calculating work hours by hand works — until it doesn't. A missed break, a decimal off, an overtime trigger you caught after payday. The bigger your team gets, the more expensive those mistakes become.

Homebase's free time clock handles all of it automatically:

• Your team clocks in and out from their phones
• Breaks are logged in real time
• Minutes convert to decimals automatically
• Overtime is flagged before it hits payroll
• Hours export directly to your payroll system

Join more than 100,000 small businesses who rely on Homebase to keep their teams paid.

Get started with Homebase for free.

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Frequently asked questions about calculating work hours

How many hours is 7:30 to 4:30?

7:30 AM to 4:30 PM is 9 gross hours — subtract a 30-minute unpaid lunch where the employee was fully off duty and net hours worked are 8.5 hours, or 8.50 in decimal format for payroll. If no unpaid break was taken, the full 9 hours are compensable.

How many hours is 8 AM to 4 PM?

8 AM to 4 PM is 8 gross hours — subtract a 30-minute unpaid meal break where the employee was fully relieved of duties and net hours worked drop to 7.5 hours, or 7.50 in decimal format for payroll. If no unpaid break was taken, all 8 hours are compensable.

How do you calculate hours and minutes worked?

To calculate hours and minutes worked, subtract your start time from your end time to get gross hours, subtract any unpaid breaks of 30 minutes or more, then divide the remaining minutes by 60 to convert to a decimal — for example, 8 hours and 20 minutes becomes 8.33 decimal hours.

What is the formula for calculating work hours?

The formula for calculating work hours is: End time − Start time − Unpaid breaks = Hours worked — then divide any remaining minutes by 60 to convert to decimals for payroll, and apply 1.5 times the regular rate to any weekly hours over 40 for overtime.

How do you convert time to decimal hours?

To convert time to decimal hours, divide the minutes by 60 and add the result to the whole hours — for example, 15 minutes ÷ 60 = 0.25, 30 minutes ÷ 60 = 0.50, and 45 minutes ÷ 60 = 0.75, giving you the decimal format your payroll system requires.

How do you subtract lunch breaks from work hours?

To subtract lunch breaks from work hours, deduct the full duration of any unpaid meal break where the employee was completely relieved of all duties for 30 minutes or more — short breaks under 20 minutes are always paid time under the FLSA and should never be subtracted from the total.

How to calculate payroll hours

To calculate payroll hours, convert each employee's daily clock-in and clock-out times to decimal hours, subtract any unpaid breaks, then add the daily totals for the week. Multiply the weekly decimal total by the hourly rate to get gross wages. Any hours over 40 must be paid at 1.5 times the regular rate.