Example 1 (simple): 160 hours at 8 hours a day
- Working days = 160 ÷ 8 = 20 days
- Working weeks = 20 ÷ 5 = 4 weeks
These are the calculator's default inputs.
Hours to Working Days Calculator: Convert Hours to Days and Weeks
Turn a number of hours into working days and weeks, or working days into hours, using your own length of working day.
Quick answer
Working days = hours ÷ hours per working day. At 8 hours a day, 160 hours is 20 working days, or 4 five-day weeks. To go the other way, multiply days by hours per day: 15 days at 7.5 hours is 112.5 hours. Use your real productive hours, not the length of the paid day.
How to read your result
Choose a direction, enter a value, and set the length of your working day and week.
- Working days (hours to days): the exact quotient, which may have a fraction. 250 hours at 6.5 hours a day is 38.46 days.
- Whole days (rounded up): the number of calendar working days you must reserve. Part of a day still takes up a day on the calendar, so 38.46 becomes 39.
- Working weeks: working days divided by working days per week. It is a planning figure and ignores holidays.
- Hours (days to hours): working days multiplied by hours per day.
The result is a count of working time, not a date. To turn the count into a finish date that skips weekends and holidays, use the project time calculator.
Hours and working days formulas
working days = hours ÷ hours per working day
working weeks = working days ÷ working days per week
hours = working days × hours per working day
Rounding up to whole days is ⌈ working days ⌉. Nothing else is involved: the calculator does not change the hours or assume breaks, because the hours per day input is meant to be the time you actually expect to spend working.
Worked examples
Each example uses numbers you can load into the calculator above; the results match the tool exactly.
Example 2 (realistic): 250 hours at 6.5 productive hours a day
A freelancer has quoted 250 hours. Between email, calls and admin, a realistic day of project work is 6.5 hours.
- Working days = 250 ÷ 6.5 = 38.46 days
- Whole days = 39
- Working weeks = 38.46 ÷ 5 = 7.69 weeks
At a full 8 hours a day the same job looks like 31.25 days, which is more than a week shorter. That difference is why the hours per day input matters.
Example 3: days to hours
A contractor is booked for 15 working days at 7.5 hours a day.
- Hours = 15 × 7.5 = 112.5 hours
- Working weeks = 15 ÷ 5 = 3 weeks
Quick reference: common hour totals
These values assume a five-day week. Use the calculator for any other combination.
| Hours | At 6 h/day | At 7 h/day | At 8 h/day | Weeks at 8 h/day |
|---|---|---|---|---|
| 40 | 6.67 days | 5.71 days | 5 days | 1 weeks |
| 80 | 13.33 days | 11.43 days | 10 days | 2 weeks |
| 160 | 26.67 days | 22.86 days | 20 days | 4 weeks |
| 320 | 53.33 days | 45.71 days | 40 days | 8 weeks |
How to convert hours to working days by hand
- Decide the length of a working day. Use productive hours: 8 for a full day on one task, 6 to 7 if meetings and admin take part of the day.
- Divide the hours by that figure. 160 ÷ 8 = 20.
- Round up if you need whole days. 38.46 becomes 39.
- Divide by days per week to get weeks: 20 ÷ 5 = 4.
- To reverse it, multiply the number of days by hours per day.
Assumptions, limits and common mistakes
Assumptions and limits
- The calculation is linear and does not know about breaks, holidays or part-time schedules. Describe those through the hours per day and days per week inputs.
- Working weeks assume the same number of working days every week.
- Calendar dates are not calculated here. Use the project time calculator for a finish date.
Common mistakes
- Using 24 hours. A working day is not a calendar day. Dividing by 24 gives elapsed days, not working days.
- Using the paid day instead of the productive day. An 8-hour contract day usually contains fewer than 8 hours of project work.
- Forgetting to round up when booking days. 38.46 days needs 39 slots.
- Assuming a 40-hour week is the same everywhere. Enter your own days per week and hours per day.
Frequently asked questions
How do I convert hours to days?
Divide the hours by the hours in a working day. For an 8-hour day, 40 hours is 5 days and 160 hours is 20 days.
How many working days is 8 hours?
One working day, if your working day is 8 hours long. At 6 hours a day, 8 hours is 1.33 days.
How many working days is 40 hours?
Five days at 8 hours a day, 5.71 days at 7 hours a day and 6.67 days at 6 hours a day. At 8 hours a day that is one working week.
How do I convert days to hours?
Multiply the working days by hours per day. Fifteen days at 7.5 hours a day is 112.5 hours.
What is the difference between a working day and a calendar day?
A working day is a day on which work normally happens, usually Monday to Friday. A calendar day is any day. Ten working days normally span 14 calendar days, because they include two weekends.
Should I use 8 hours for a working day?
Only if the person really spends 8 hours on the work. Many teams plan with 6 to 7 productive hours because of meetings and interruptions. The results are only as realistic as that input.
How many working weeks is 160 hours?
At 8 hours a day and 5 days a week, 160 hours is 4 working weeks.
How do I turn hours into a finish date?
First convert the hours into working days, then count that many working days forward from the start date while skipping weekends and holidays. The project time calculator does this and also handles team size and buffer.
Last updated 19 October 2026. Last reviewed 19 October 2026. Reviewed by Umesh Manral. Formulas and tests: methodology.