[ man-dey ]
/ ˈmænˌdeɪ /
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noun, plural man-days.
a unit of measurement, especially in accountancy; based on a standard number of man-hours in a day of work.
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Origin of man-day

First recorded in 1920–25
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What does man-day mean?

Man-day is a unit of measurement referring to the amount of work that one person does in one day.

Man-day is often used in accounting and other business contexts, especially when estimating and budgeting for how much work it will take to complete a project, as well as how long it will take and how much it will cost. For example, if a team of three people takes two working days to finish a project, it takes six man-days.

Of course, man-days don’t just count work done by men. A neutral alternative term for man-day is person-day.

Example: We estimate that it will take about 150 man-days to complete the walkway, so make sure we budget for that.

Where does man-day come from?

The first records of man-day come from the 1920s. The related and much more common term man-hour is recorded earlier, around 1915. Man-hour measures the same thing a man-day, except for hours instead of days. Both man-hour and man-day are most often used in the plural, as in It will take us 17 man-hours to complete this project or We will be to finish in seven business days, but it will take 28 man-days.

When overseeing a project, whether it is the construction of a skyscraper or the publishing of a magazine, there are different ways to say how long it will take to be completed (such as by giving a number of calendar days or business days). But a man-day is a measure of how much work a project will take. So saying something will take 30 man-days is the same as saying it will take 30 people one day to do it, or one person 30 days, or six people five days, and so on. Each person’s day of work is counted separately. Generally, a man-day is understood as an eight-hour period of work by one person, but the amount of time can vary. Of course, it’s not always so simple to calculate. Some people may work half-days, and not every might work every day. In any case, counting man-days allows for a more precise picture of how much work something will take—and how much it will cost.

Like many terms that originated in the 1900s or earlier, man-day uses man instead of person. Much like how businessman is now often changed to businessperson, person-day is often used instead of man-day.

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What are some other forms of man-day?

  • man-days (plural)

What are some synonyms for man-day?

What are some words that often get used in discussing man-day?

How is man-day used in real life?

Man-day is generally used in a business context when calculating how much labor is needed to complete a project, or in discussions of efficiency.



Try using man-day!

True or false? 

The term man-day specifically refers to a workday of a man, as opposed to a woman.

How to use man-day in a sentence