Work Hours Calculator — Breaks & Timesheets

Enter the date, start time, end time and total break in minutes. The calculator subtracts the break from the shift span and displays hours:minutes, decimal hours and total minutes. For example, 09:00–18:00 with a 60-minute break gives 8:00, 8.00 hours and 480 minutes.

Use Single day for a quick check, or Multiple days for a timesheet of up to 31 workdays. Each row represents one date. Duplicate dates and overlapping shifts are rejected instead of being counted twice. The five-weekday reset replaces your rows after confirmation; download JSON first if you want to keep them.

No account is needed. Work data is read, calculated and exported in your browser. Ordinary page requests and site analytics are separate from the timesheet contents.

If the end clock time is earlier than the start, it is treated as the following day. Equal start and end times are invalid: the calculator does not assume a 24-hour shift. Each row must be shorter than 24 hours. Clock times are used directly; daylight-saving transitions and time zones are not resolved.

Enter your total break, then enter how much of that break fell inside the night window. The night break is part of the total break, not an additional deduction. Night work is also part of total work, not time to add on top. The duration bar shows work versus break totals, not the actual timing of breaks.

For 22:00–06:00 with a 60-minute break, work time is 7:00. If all 60 break minutes were inside 22:00–05:00, night work is 6:00. The calculator checks that the break allocation can fit both inside and outside the chosen window. It cannot infer when you actually took a break.

Time subtraction is general, but pay estimates are in Japanese yen (JPY). The default night window is 22:00–05:00; the optional estimate adds 25% of the hourly rate for night work after night breaks. Choosing another window disables that premium estimate. Hiding night hours changes the display only; use the separate premium checkbox to exclude the additional amount.

Break notices follow Japan's general thresholds: more than 6 hours of work calls for at least 45 minutes of break, and more than 8 hours calls for at least 60 minutes. These notices do not assess exceptions, contracts or whether a break was actually free from work. Rules outside Japan differ.

This is not payroll software or a compliance determination. Overtime, statutory holidays, tax, wage-base exclusions and individual arrangements are not calculated. Check the original records and applicable rules before using an estimate.

8:30 means eight hours and thirty minutes, equivalent to 8.50 decimal hours, not 8.30. Display rounding can use 5, 10, 15 or 30 minutes and round up, down or to the nearest interval. It changes each row's reference time display only. Totals and pay use the original minutes.

Base and total pay estimates are rounded to whole yen per row. The night-premium component is their difference, so the displayed components add up. Monthly totals sum the displayed row amounts. This is the calculator's reference convention, not a guarantee of your employer's payroll rounding.

Copy results or export CSV for the visible rows. CSV includes English headers, original and rounded work time, night work, yen amounts and checks. Download JSON to retain all rows, including those hidden in Single day, plus settings. Load that JSON to resume in either the Japanese or English calculator. CSV is an export format, not an import format.

JSON files are limited to 512 KiB and 31 rows. Invalid files are checked before the current timesheet is replaced. Editing while a file is loading cancels that load. Download your JSON before closing or reloading the page: timesheets are not automatically saved in browser storage or on the server.