Hours to weeks:
divide by 168

How many weeks are in an hour?

One hour is 0.005952380952 weeks, or about 0.006 weeks. The reverse is easier to remember: a week has exactly 168 hours, because 7 days times 24 hours is 168. Nothing is rounded, as long as you mean a plain calendar week.

Time units here follow the fixed definitions: 60 minutes to the hour, 24 hours to the day and 7 days to the week. Months and years vary in length, so they are not part of this conversion.

The hours to weeks formula

A second worked example: 90 hours of machine run time is 90 ÷ 168 = 0.5357 weeks. That is a little more than half a week, or about 3 days and 18 hours.

1. 1Write the time in hours.
2. 2Divide by 168.
3. 3Turn any decimal part into days by multiplying by 7 if you want a schedule.
4. 4Check: 168 hours must give exactly 1 week.

Chart: hours to weeks

The values below are calendar weeks, where every hour of the day counts.

Easy anchor points are 168 h for one week, 336 h for two weeks and 504 h for three weeks.

Calendar weeks and working weeks

The 168-hour figure counts every hour, including nights and weekends. A person on a 40-hour working week uses 40 ÷ 168 = 23.8 percent of the calendar week. That is why a task of 80 working hours takes two working weeks, not 80 ÷ 168 = 0.48 weeks.

Use the formula above for things that run around the clock, such as server uptime, a laboratory incubation, a machine that runs overnight or a parcel in transit. For staff effort, divide by the hours worked per week instead, such as 40 or 37.5, depending on the contract.

Another quick example: a 1000-hour warranty on a part that runs continuously lasts 5.95 weeks, just under six weeks. If the same part only runs 8 hours a day, five days a week, the 1000 hours stretch over 25 working weeks.

Rotas show the difference clearly. A nurse working 12-hour shifts for three shifts a week works 36 hours, which is 36 ÷ 168 = 0.2143 of the calendar week. Employers use both views: the calendar week describes cover over 24 hours, while the working week describes the contract.

Common mistakes when converting hours to weeks

• Using 40 or 120 hours as a week. Those are working-week or five-day figures, not the 168 hours of a calendar week.
• Multiplying instead of dividing. A week is the larger unit, so a number of weeks is smaller than the number of hours.
• Reading 0.5 weeks as 5 days. Half a week is 3.5 days, or 84 hours.
• Treating the decimal part as days. 2.98 weeks is not 2 weeks and 98 days. Multiply 0.98 by 7 to get days.