Prescribed Working Hours in Japan: Daily, Monthly, and Annual-Average Calculations
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Last Updated:
Category: Work Styles
Authors: Shusaku Yosa
Prescribed working hours are the working hours set by an employment contract or work rules, excluding breaks. A schedule from 9 a.m. to 5:30 p.m. spans eight and a half hours, but with a one-hour break it contains seven and a half prescribed working hours.
This guide explains how to read daily schedules, calculate the hours for a particular month, and distinguish them from an annual monthly average. It concerns employment in Japan. Legal information was checked on October 16, 2026; all calculation examples are fictional.
Four different measures
Measure | Meaning | Where to check |
|---|---|---|
Prescribed hours | Work scheduled under the contract or rules | Written employment conditions, work rules, roster |
Statutory hours | The legal framework, generally eight hours a day and 40 a week | The working-time system that applies |
Actual hours worked | Time actually spent working | Clock records, work records, actual breaks |
Total scheduled span | Time from starting to finishing, including breaks | Start, finish, and break times |
Variable working-hour systems, flextime, and certain workplace exceptions require a more specific review. A scheduled day longer than eight hours does not by itself settle the legal position. See the ministry's working-time rules.
Paid leave also illustrates the distinction: hours scheduled under the contract and hours actually worked are different records. Do not automatically turn the prescribed hours into zero because someone took leave.
Calculate a daily schedule
Subtract the starting time and the break from the finishing time. For decimal calculations, 30 minutes is 0.5 hours and 45 minutes is 0.75 hours. Seven hours and 30 minutes is 7.5 hours, not 7.3.
Schedule | Break | Prescribed work |
|---|---|---|
9:00–17:30 | One hour | 7.5 hours |
9:00–18:00 | One hour | Eight hours |
10:00–16:00 | None | Six hours |
Examine whether a nominal break is actually free from work. A requirement to answer business calls raises a separate issue from the printed schedule. The ministry's break FAQ explains the six- and eight-hour thresholds.
A particular month is different from a monthly average
If the daily schedule is constant, multiply daily prescribed hours by that month's prescribed workdays. At 7.5 hours a day, 20 scheduled days produce 150 hours; 22 days produce 165 hours.
An annual monthly average instead uses total annual prescribed hours divided by 12. It comes from the annual company calendar and need not equal the scheduled hours in every individual month. The Osaka Labour Bureau provides an example of a monthly-salary hourly conversion.
Fictional annual schedule | Annual hours | Monthly average |
|---|---|---|
245 days at eight hours | 1,960 | About 163.33 |
245 days at 7.5 hours | 1,837.5 | 153.125 |
The 245 days are an assumption, not a universal legal requirement. A 365-day year with 120 company holidays gives 245 scheduled workdays in this example. Do not add an employee's actual paid-leave days to company holidays and recalculate the contractual calendar on that basis. If daily hours vary, add the scheduled hours for each day instead of multiplying by one constant.
Passing 160 hours does not automatically establish statutory overtime
Neither 160 hours nor an annual monthly average is a universal legal monthly ceiling. Under an ordinary working-time system, examine daily and weekly statutory hours and distinguish work beyond the agreed schedule from statutory overtime.
Working eight hours on a day scheduled for 7.5 produces half an hour beyond the prescribed schedule. Looking only at that day's actual total, eight hours has not been exceeded. The weekly total and wage rules also matter. Payment for the additional work and entitlement to a statutory premium are separate questions; work within statutory limits is not automatically unpaid.
A weekly statutory limit can also matter even where each day's prescribed schedule is observed. Keep dated records instead of relying only on a monthly total. Our Labor Standards Act introduction explains the broader framework.
Questions for payroll or a prospective employer
- Confirm start, finish, break, and prescribed daily hours.
- Separate this month's workdays from the annual company calendar.
- Ask which period and formula a stated monthly average uses.
- Check why the payroll denominator differs from actual hours in the attendance screen.
- Ask how additional work, fixed overtime components, and excess hours are paid.
A useful question is: “Does the 163.33-hour monthly average come from annual prescribed workdays and daily hours? This month's roster shows 160 hours, so I would like to understand how each number is used.” A difference between the figures does not establish an error without understanding their purpose.
When comparing jobs, the same monthly salary can accompany different scheduled hours. Ask for ordinary- and busy-month examples, when preparation is recorded, and how confirmed shifts change. During a visit or trial, compare those explanations with the way work starts and breaks happen.
For related reading, use our written employment conditions guide and two-day weekend terminology guide.
