Ningetsu (person-month) / Ninnichi (person-day)｜A Perfect Guide to Get Jobs and Work in Japan

Both of the following terms are used predominantly in the IT field as units of measurement to estimate an amount of work.

人月にんげつ ningetsu (person-month)

A person-month is the amount of work done by one person in one month, often based on the assumption of 20 work days in a month. This unit helps measure or estimate the total length of time required to complete a task or project.

例： 1人のプログラマーが1か月働く場合のコストを「人月単価」と言います。
　　The cost of one programmer working for one month is called the “unit cost per person-month”.

人日にんにち ninnichi　(person-day)

A person-day is the amount of work done by one person in one day, often based on the assumption of 8 hours of work in a day. This unit helps measure or estimate the number of hours required to complete a task or project.

例：このプロジェクトには１０人日かかると考えた方がいいと思います。
　　I think we should plan on 10 person-days for this project.