Business Hours Calculator
Calculate working hours between two dates and times, counting only weekdays within your office hours. Set your work-day window for accurate business-hour totals.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
How it works
How the Business Hours Calculator Works
This tool measures the working hours between two date-times, counting only weekdays and only the hours inside your office window. Enter a start and end date-time, set when the work day opens and closes (on a 24-hour clock), and it returns the total business hours, the equivalent business days, and how many working days the range touches.
It correctly handles partial first and last days: if your range starts at 2:00 PM, only the working hours after 2:00 PM that day are counted.
The Formula
For each calendar day between the start and end:
If the day is Mon-Fri, add the overlap between your [start, end] range and that day’s [open, close] window.
In symbols, the hours counted on a given weekday are:
max(0, min(end, close) − max(start, open))
summed across every weekday in the range. Business days are then total hours divided by the length of one working day.
Worked Example
Suppose the range is Monday 9:00 AM to Wednesday 3:00 PM, with office hours 9:00 to 17:00 (an 8-hour day):
- Monday: 9:00 to 17:00 = 8 hours
- Tuesday: full working day = 8 hours
- Wednesday: 9:00 to 15:00 = 6 hours
- Total = 8 + 8 + 6 = 22 business hours = 22 ÷ 8 = 2.75 business days
Working-Window Reference
| Office hours | Hours per day | Hours per 5-day week |
|---|---|---|
| 9:00 - 17:00 | 8 | 40 |
| 9:00 - 18:00 | 9 | 45 |
| 8:00 - 16:00 | 8 | 40 |
| 9:00 - 17:00 with no lunch counted | 8 | 40 |
| 9:00 - 16:00 (7-hour day) | 7 | 35 |
Why Use a Business Hours Calculator?
Service-level agreements, support ticket deadlines, payroll, and project estimates are almost always measured in working hours, not raw clock hours. A “24 business-hour” response target is very different from 24 calendar hours once weekends and overnight closures are removed. This calculator gives you the true working-time figure so deadlines and timesheets stay accurate.
Frequently asked questions
How are business hours calculated between two dates?+
The calculator walks through every calendar day between your start and end times, skips Saturdays and Sundays, and for each weekday adds the number of hours that fall inside your working window (for example 9:00 to 17:00). The overlaps are summed to give the total.
Does this include weekends?+
No. Saturdays and Sundays are excluded automatically. Only Monday through Friday are counted, and only the hours that lie within the working window you set.
How many business hours are in a standard work week?+
A standard 9-to-5 week with a one-hour window of 8 working hours per day over five weekdays totals 40 business hours. If your day is 9:00 to 17:00 with no break, that is 8 hours times 5 days.
Can I set custom office hours?+
Yes. Enter your work-day start and end on a 24-hour clock (for example 8.5 for 8:30). The calculator only counts time inside that window each weekday, so partial first and last days are handled correctly.
Does it account for lunch breaks or public holidays?+
Not automatically. The tool counts a continuous working window per weekday and does not subtract lunch or skip national holidays. For an unpaid lunch break, shorten your window (for example 9:00 to 16:00 for a 7-hour day).