If I work 9:00 to 18:00 with a 1-hour break, how many hours is that?

It is 8 hours of actual work. The time at work is 9 hours, but the 1-hour break does not count as working time, so 18:00 − 9:00 − 1:00 = 8 hours. The statutory working hours (法定労働時間) are 8 hours a day, so this schedule produces no statutory overtime. Time worked after 18:00 earns a premium of at least 25%. Note that at a company whose scheduled working hours are 7 hours (9:00 to 17:00 with a 1-hour break), the hour worked from 17:00 to 18:00 is called within-statutory overtime (法定内残業), and the law permits paying it at the regular 1.0x rate with no premium.

After how many hours does overtime start?

Overtime is time beyond 8 hours a day or 40 hours a week (Article 32 of the Labor Standards Act). Exceeding either one makes it statutory overtime, and a premium wage of at least 25% is required (Article 37). Because this tool calculates from a single day’s input, it shows time beyond 8 hours as “statutory overtime”. If you work 6 days a week and stay within 8 hours a day but exceed 40 hours a week, the excess is also overtime, so check the weekly total on the monthly tab. The monthly cap is, in principle, 45 hours once an Article 36 Agreement (36協定) is in place, and even with special provisions it must stay under 100 hours in a single month.

What hours does the late-night premium (深夜手当) cover?

From 22:00 to 5:00 the next morning (Article 37, paragraph 4 of the Labor Standards Act). Work in this window adds at least 25% to normal pay. The late-night premium is added to other premiums, so overtime after 22:00 earns 25% + 25% = 50%, and late-night work on a statutory holiday earns 35% + 25% = 60%. With an hourly wage of 1,200 yen, one hour of late-night overtime pays 1,800 yen. The late-night premium also applies to managers in supervisory positions (管理監督者). Even though the overtime and holiday premiums do not apply to them, the late-night premium must still be paid.

Is rounding down to 15-minute units illegal?

Rounding down each day is illegal. Article 24 of the Labor Standards Act requires full payment for time worked, so counting a 9:00 to 18:10 shift only up to 18:00 amounts to unpaid wages for 10 minutes. As an exception, when the monthly total of overtime, holiday work or late-night work has a fraction of less than 1 hour, rounding fractions under 30 minutes down and 30 minutes or more up to 1 hour is permitted by administrative guidance (Notice No. 150 of the Labor Standards Bureau, March 14, 1988). This is monthly fraction handling and is a different matter from daily rounding down. Rounding up does not disadvantage workers, so rounding up in 15-minute units is not a problem.

How do I count a night shift that crosses midnight?

A shift starting at 22:00 and ending at 6:00 the next morning is not split into two days; it is counted as one shift belonging to the day on which it started. This tool automatically treats an end time earlier than the start time as the next day, so entering “22:00” and “6:00” as they are gives 8 hours at work. It also understands “翌6:00” and “30:00”. In this example, with a 1-hour break the actual work is 7 hours, and 7 hours fall within late-night hours (22:00 to 5:00), so the 25% premium is added to the time left after subtracting any break taken during late-night hours.

How many minutes of break must be given?

At least 45 minutes when actual work exceeds 6 hours, and at least 1 hour when it exceeds 8 hours (Article 34 of the Labor Standards Act). Exactly 6 hours requires no break, and 6 hours 1 minute requires 45 minutes. Exactly 8 hours needs only 45 minutes, but even 1 minute over requires 60 minutes, so on days with overtime many workplaces simply give a full hour from the start. A break must be given during working hours and must be freely usable, so standing by to answer the phone does not count as a break. This tool shows the shortfall when the break you enter is below the standard.

How is overtime pay calculated? What is the hourly rate for monthly salary?

Overtime pay is “hourly wage × 1.25 × overtime hours”. For monthly-salaried workers, the hourly wage is “monthly salary ÷ average monthly scheduled working hours”. Average monthly scheduled working hours are “(365 days − annual days off) × scheduled hours per day ÷ 12”; with 120 annual days off and 8 hours a day, that is (365 − 120) × 8 ÷ 12 = about 163.3 hours. A monthly salary of 250,000 yen gives an hourly wage of roughly 1,531 yen. Family allowances, commuting allowances, housing allowances, bonuses and the like may be excluded from the base for premium wages. Enter the hourly wage you worked out into this tool to see the amount including premiums.

What is the premium for overtime beyond 60 hours a month?

It is at least 50% (proviso to Article 37, paragraph 1 of the Labor Standards Act). It has applied to large companies for some time and was extended to small and medium-sized companies in April 2023. Overtime is paid at 25% until it reaches 60 hours in the month, and at 50% beyond that. For example, with 80 hours of overtime in a month, 60 hours are calculated at 1.25x and the remaining 20 hours at 1.5x. The tool’s “Monthly total” tab stacks overtime in date order and automatically separates the part beyond 60 hours. There is also a system for converting the premium on the excess into paid substitute leave (代替休暇), but it requires a labor-management agreement.

What is the premium for working on a statutory holiday?

At least 35% (Article 37 of the Labor Standards Act). A statutory holiday is the one day off a week (or four days off in four weeks), and because holiday work has no concept of overtime, even 10 hours of work is entirely paid at the 35% premium. Working into late-night hours adds 25%, for 60% in total. Note that at a company with weekends off, Saturday is often not a statutory holiday but a scheduled holiday (所定休日, a day off set by the company). Work on a scheduled holiday does not earn 35%; instead, 25% applies to hours beyond 40 a week. Check your company’s work rules to see which applies. In this tool, a day whose “Holiday” box is ticked on its row is calculated as a statutory holiday.

Can I calculate a whole month at once?

Yes. On the “Monthly total” tab, add rows or paste rows copied from a timecard or spreadsheet into “Paste in bulk”. If each row is in the order date, start, end, break (minutes), as in “9/1 9:00 18:00 60”, it is read whether separated by tabs, commas or spaces. A row ending in “休” (holiday) is calculated as a statutory holiday. Results show daily working, overtime and late-night hours plus monthly totals, and you can copy the table and paste it into a spreadsheet. What you enter is stored only on this device.

Can I get “8 hours 30 minutes” as a decimal for payroll?

Yes. The actual-hours card shows “8:30” and “8.5 hours” side by side. Payroll multiplies the hourly wage by hours as a decimal, so you need conversions such as 30 minutes = 0.5, 15 minutes = 0.25 and 10 minutes = 0.166…, and a mistake in this conversion throws the amount off. On the “Time addition” tab, the total of several times added or subtracted is shown in four ways: base-60 (H:MM), Japanese notation, decimal and minutes. If you want to stack up work time to get an invoice amount, entering an hourly wage calculates the amount at the same time.

The result doesn’t match my company’s timekeeping system.

Most often it is a rounding setting or a difference in how breaks are handled. First, set “Rounding of actual hours” in the common settings to the unit (15 minutes, 30 minutes, etc.) and rounding method written in your company’s work rules. Next, check whether breaks are deducted automatically and whether scheduled working hours are under 8 hours, such as 7 hours 45 minutes. At a company with 7 hours 45 minutes scheduled, the 15 minutes until reaching 8 hours may be calculated as within-statutory overtime with no premium. If it still doesn’t match, a fixed overtime allowance (みなし残業) covering a set number of hours a month may be included.

Work Hours Calculator (Overtime, Late-Night Premium, Hourly Pay)

Enter your start time, end time and break, and the tool shows actual working hours both as “8 hours 30 minutes” and “8.5 hours”, and automatically separates statutory overtime (hours beyond 8 per day under Japan’s Labor Standards Act, 労働基準法) from late-night hours (22:00 to 5:00 the next morning). It also handles overnight shifts such as 22:00 to 6:00 the next day, rounding in 15-minute units, and the 35% premium for statutory holidays (法定休日). Paste a timecard into the monthly tab to get monthly totals for working, overtime and late-night hours, plus a pay estimate that includes the 50% premium for overtime beyond 60 hours a month. The time-addition tab also does base-60 arithmetic such as 1:30 + 2:45.

ABOUT

About Work Hours Calculator (Overtime, Late-Night Premium, Hourly Pay)

The work hours calculator takes your clock-in, clock-out and break times and gives you the day’s actual working hours, automatically separating statutory overtime (anything beyond 8 hours a day) from late-night hours (22:00 to 5:00 the next morning). Results are shown both as “8 hours 30 minutes” and “8.5 hours”, so they work for copying onto a timecard and for payroll. It handles overnight shifts such as 22:00 to 6:00 the next day, rounding in 15- or 30-minute units, and the 35% premium for statutory holidays (法定休日). Paste a timecard into the monthly tab to get monthly totals for working, overtime and late-night hours, plus a wage estimate that includes the 50% premium on overtime beyond 60 hours a month. The time-addition tab also handles base-60 arithmetic such as 1:30 + 2:45 and questions like “what time is it 3 hours 45 minutes after 17:30?”.

How to use Work Hours Calculator (Overtime, Late-Night Premium, Hourly Pay)

1On the “Daily hours” tab, enter your start and end times (9:00, 900 and 9時半 are all understood)
2Enter your break in minutes (you can also pick 60 or 45 minutes with the buttons)
3Check the actual working hours, statutory overtime, late-night hours and the bar chart of the work period
4Enter an hourly wage to see a pay breakdown including premiums (category, hours, rate, amount)
5To match your company’s rounding, choose a unit such as “15 minutes” and a rounding method in the common settings below
6To total a whole month, add rows on the “Monthly total” tab or paste a whole timecard at once

Great for

Check a day’s actual working hours and overtime while looking at a timecard or shift table
Total a part-timer’s monthly hours and compare them with the pay slip
Count how many late-night hours an overnight shift or on-call duty includes
Verify that the overtime pay you received was calculated at the correct premium rates
See how much difference a “round down to 15 minutes” policy makes over a month
As a shift planner, check that shifts stay within 8 hours a day and 40 hours a week and that breaks are sufficient
Keep track mid-month of whether you are nearing the Article 36 Agreement (36協定, the overtime labor-management agreement) limits of 45 hours a month and under 100 hours in a single month
Add up work time for an estimate or invoice, such as 1:30 + 2:45
Work out times such as “what time is it 3 hours 45 minutes after 17:30?”

Good to know

Actual working hours are calculated as end time − start time − break. Hours beyond 8 are statutory overtime (Articles 32 and 37 of the Labor Standards Act, 労働基準法).
Late-night hours are 22:00 to 5:00 the next day. The 25% late-night premium is added on top of other premiums, so overtime that runs into late-night hours earns 25% + 25% = 50%.
Under Article 34 of the Labor Standards Act, a break of at least 45 minutes is required when actual work exceeds 6 hours, and at least 1 hour when it exceeds 8 hours. The screen warns you if your break is too short.
If the end time is earlier than the start time, it is treated as a shift crossing midnight and the end time is read as the next day. You can also enter it as “翌6:00” (next day 6:00) or “30:00”.
A shift that crosses midnight is, in principle, counted as work of the day on which it started (continuous work is treated as a single shift).
Rounding down to 15-minute units each day means pay is not given for time actually worked, which violates Article 24 of the Labor Standards Act (full payment of wages). This tool defaults to “no rounding”.
When the monthly total of overtime, holiday work or late-night work has a fraction of less than 1 hour, rounding fractions under 30 minutes down and 30 minutes or more up to 1 hour is permitted by administrative guidance. You can reproduce this with “Round monthly total fractions at 30 minutes”.
The break field only takes a total number of minutes, so if a break falls within late-night hours, subtract it in the “Break taken during late-night hours” field.
Overtime is counted from the end of the shift (assuming the break is taken at midday). For a shift that actually starts in the late-night hours, the way late-night and overtime hours overlap may differ.
The pay shown is an estimate calculated from the premium rates. Actual pay varies with company work rules, fixed overtime allowances (みなし残業, deemed overtime), and deductions for social insurance and income tax.
Hours beyond 40 a week are also overtime, but this cannot be determined from daily inputs, so the tool calculates using more than 8 hours a day and statutory holidays.
The work hours and hourly wage you enter are stored only in this device’s browser and are never sent to a server.

Questions this tool answers

Use Work Hours Calculator (Overtime, Late-Night Premium, Hourly Pay) for searches like these:

Calculate actual working hours from clock-in and clock-out times
Find out how many hours I work from 9:00 to 18:00 with a 1-hour break
Work out how many hours of overtime I did that day
Calculate how much overtime pay comes from an hourly wage
Find out when the late-night premium starts and how much it adds
Count hours and late-night hours for a night shift that crosses midnight
Paste a timecard and total a month’s working hours
Find out whether rounding down to 15-minute units is illegal
Check the premium rate for overtime beyond 60 hours a month
Find out the premium rate for working on a statutory holiday
Convert 8 hours 30 minutes into a decimal like 8.5 hours
Add times such as 1:30 + 2:45
Find out what time it is 3 hours 45 minutes after 17:30
Check how many minutes of break must be given

FAQ

If I work 9:00 to 18:00 with a 1-hour break, how many hours is that?: It is 8 hours of actual work. The time at work is 9 hours, but the 1-hour break does not count as working time, so 18:00 − 9:00 − 1:00 = 8 hours. The statutory working hours (法定労働時間) are 8 hours a day, so this schedule produces no statutory overtime. Time worked after 18:00 earns a premium of at least 25%. Note that at a company whose scheduled working hours are 7 hours (9:00 to 17:00 with a 1-hour break), the hour worked from 17:00 to 18:00 is called within-statutory overtime (法定内残業), and the law permits paying it at the regular 1.0x rate with no premium.
After how many hours does overtime start?: Overtime is time beyond 8 hours a day or 40 hours a week (Article 32 of the Labor Standards Act). Exceeding either one makes it statutory overtime, and a premium wage of at least 25% is required (Article 37). Because this tool calculates from a single day’s input, it shows time beyond 8 hours as “statutory overtime”. If you work 6 days a week and stay within 8 hours a day but exceed 40 hours a week, the excess is also overtime, so check the weekly total on the monthly tab. The monthly cap is, in principle, 45 hours once an Article 36 Agreement (36協定) is in place, and even with special provisions it must stay under 100 hours in a single month.
What hours does the late-night premium (深夜手当) cover?: From 22:00 to 5:00 the next morning (Article 37, paragraph 4 of the Labor Standards Act). Work in this window adds at least 25% to normal pay. The late-night premium is added to other premiums, so overtime after 22:00 earns 25% + 25% = 50%, and late-night work on a statutory holiday earns 35% + 25% = 60%. With an hourly wage of 1,200 yen, one hour of late-night overtime pays 1,800 yen. The late-night premium also applies to managers in supervisory positions (管理監督者). Even though the overtime and holiday premiums do not apply to them, the late-night premium must still be paid.
Is rounding down to 15-minute units illegal?: Rounding down each day is illegal. Article 24 of the Labor Standards Act requires full payment for time worked, so counting a 9:00 to 18:10 shift only up to 18:00 amounts to unpaid wages for 10 minutes. As an exception, when the monthly total of overtime, holiday work or late-night work has a fraction of less than 1 hour, rounding fractions under 30 minutes down and 30 minutes or more up to 1 hour is permitted by administrative guidance (Notice No. 150 of the Labor Standards Bureau, March 14, 1988). This is monthly fraction handling and is a different matter from daily rounding down. Rounding up does not disadvantage workers, so rounding up in 15-minute units is not a problem.
How do I count a night shift that crosses midnight?: A shift starting at 22:00 and ending at 6:00 the next morning is not split into two days; it is counted as one shift belonging to the day on which it started. This tool automatically treats an end time earlier than the start time as the next day, so entering “22:00” and “6:00” as they are gives 8 hours at work. It also understands “翌6:00” and “30:00”. In this example, with a 1-hour break the actual work is 7 hours, and 7 hours fall within late-night hours (22:00 to 5:00), so the 25% premium is added to the time left after subtracting any break taken during late-night hours.
How many minutes of break must be given?: At least 45 minutes when actual work exceeds 6 hours, and at least 1 hour when it exceeds 8 hours (Article 34 of the Labor Standards Act). Exactly 6 hours requires no break, and 6 hours 1 minute requires 45 minutes. Exactly 8 hours needs only 45 minutes, but even 1 minute over requires 60 minutes, so on days with overtime many workplaces simply give a full hour from the start. A break must be given during working hours and must be freely usable, so standing by to answer the phone does not count as a break. This tool shows the shortfall when the break you enter is below the standard.
How is overtime pay calculated? What is the hourly rate for monthly salary?: Overtime pay is “hourly wage × 1.25 × overtime hours”. For monthly-salaried workers, the hourly wage is “monthly salary ÷ average monthly scheduled working hours”. Average monthly scheduled working hours are “(365 days − annual days off) × scheduled hours per day ÷ 12”; with 120 annual days off and 8 hours a day, that is (365 − 120) × 8 ÷ 12 = about 163.3 hours. A monthly salary of 250,000 yen gives an hourly wage of roughly 1,531 yen. Family allowances, commuting allowances, housing allowances, bonuses and the like may be excluded from the base for premium wages. Enter the hourly wage you worked out into this tool to see the amount including premiums.
What is the premium for overtime beyond 60 hours a month?: It is at least 50% (proviso to Article 37, paragraph 1 of the Labor Standards Act). It has applied to large companies for some time and was extended to small and medium-sized companies in April 2023. Overtime is paid at 25% until it reaches 60 hours in the month, and at 50% beyond that. For example, with 80 hours of overtime in a month, 60 hours are calculated at 1.25x and the remaining 20 hours at 1.5x. The tool’s “Monthly total” tab stacks overtime in date order and automatically separates the part beyond 60 hours. There is also a system for converting the premium on the excess into paid substitute leave (代替休暇), but it requires a labor-management agreement.
What is the premium for working on a statutory holiday?: At least 35% (Article 37 of the Labor Standards Act). A statutory holiday is the one day off a week (or four days off in four weeks), and because holiday work has no concept of overtime, even 10 hours of work is entirely paid at the 35% premium. Working into late-night hours adds 25%, for 60% in total. Note that at a company with weekends off, Saturday is often not a statutory holiday but a scheduled holiday (所定休日, a day off set by the company). Work on a scheduled holiday does not earn 35%; instead, 25% applies to hours beyond 40 a week. Check your company’s work rules to see which applies. In this tool, a day whose “Holiday” box is ticked on its row is calculated as a statutory holiday.
Can I calculate a whole month at once?: Yes. On the “Monthly total” tab, add rows or paste rows copied from a timecard or spreadsheet into “Paste in bulk”. If each row is in the order date, start, end, break (minutes), as in “9/1 9:00 18:00 60”, it is read whether separated by tabs, commas or spaces. A row ending in “休” (holiday) is calculated as a statutory holiday. Results show daily working, overtime and late-night hours plus monthly totals, and you can copy the table and paste it into a spreadsheet. What you enter is stored only on this device.
Can I get “8 hours 30 minutes” as a decimal for payroll?: Yes. The actual-hours card shows “8:30” and “8.5 hours” side by side. Payroll multiplies the hourly wage by hours as a decimal, so you need conversions such as 30 minutes = 0.5, 15 minutes = 0.25 and 10 minutes = 0.166…, and a mistake in this conversion throws the amount off. On the “Time addition” tab, the total of several times added or subtracted is shown in four ways: base-60 (H:MM), Japanese notation, decimal and minutes. If you want to stack up work time to get an invoice amount, entering an hourly wage calculates the amount at the same time.
The result doesn’t match my company’s timekeeping system.: Most often it is a rounding setting or a difference in how breaks are handled. First, set “Rounding of actual hours” in the common settings to the unit (15 minutes, 30 minutes, etc.) and rounding method written in your company’s work rules. Next, check whether breaks are deducted automatically and whether scheduled working hours are under 8 hours, such as 7 hours 45 minutes. At a company with 7 hours 45 minutes scheduled, the 15 minutes until reaching 8 hours may be calculated as within-statutory overtime with no premium. If it still doesn’t match, a fixed overtime allowance (みなし残業) covering a set number of hours a month may be included.

Special Thanks

SOLO GUILD | サービス作るAIエンジニア

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