Business Day Calculator
Calculate a date a given number of business days after a start date, or count the business days between two dates — excluding weekends and Japanese public holidays. You can also toggle whether Saturdays count as business days.
How This Tool Defines a "Business Day"
| Monday–Friday | Counted as a business day unless it is a holiday |
|---|---|
| Saturday | Not counted as a business day by default (counted if "Count Saturdays as Business Days" is enabled) |
| Japanese Public Holidays & Substitute Holidays | Always excluded from business days (uses the same data as our sister Holiday List Calendar) |
| Supported Holiday Data Range | 2017–2027 |
What business-day calculation is
This tool works out dates on the basis of business days — days other than Saturdays, Sundays and Japanese public holidays. It offers both a mode that answers “what date falls a given number of business days after the start date?” and a mode that counts “how many business days lie between two dates?”. Counting a deadline in plain calendar days drifts a long way from the real number of working days once a weekend or a run of holidays falls in the middle, so for an invoice due date or a delivery schedule, counting in business days gives a result much closer to practice.
By default Monday to Friday count as business days, and Saturdays, Sundays and public holidays (including substitute holidays) are excluded. For trades that work Saturdays, there is a switch to count Saturday as a business day too. The holiday data covers a set range of years; if your calculation runs past that range, a warning tells you the figure is a rough one based on weekdays alone, with holidays unaccounted for.
How to calculate business days
- Choose the mode Pick either “find a date from a number of days” (start date + business days → date) or “find the number of days from two dates” (start date to end date → business days).
- Enter the start date Give the date the count begins from — the invoice date, order date or date of signature, as the case may be.
- Enter the number of business days or the end date In the first mode, enter how many business days to add; in the second, enter the end date.
- Set how Saturdays are treated Tick “count Saturdays as business days” if your workplace works them. By default Saturday is treated as a non-working day.
- Read the result The result updates as you type. Do note the warning if your range extends beyond the years the holiday data covers.
Tips for getting more out of it
- Handy for checking a payment deadline like "net 30 business days" on an invoice, or a delivery/submission due date. Just set the start date to the invoice or order date and enter the number of business days to see the actual due date.
- The mode that counts business days between two dates is useful for estimating workload on a business-day basis, or checking how many working days a project actually spans.
- If Saturdays count as working days in your industry (retail, some service businesses, etc.), enable "Count Saturdays as Business Days" before calculating.
- The holiday data shares the same source (published by Japan's Cabinet Office) as our sister tools, the Holiday List Calendar and the Holiday Checker, so substitute holidays are correctly reflected too.
Where business-day calculation helps
Checking a payment deadline on an invoice or contract
For terms such as “within 30 business days of issue”, see immediately what calendar date the deadline actually falls on.
Estimating delivery and lead times
Work out a dispatch or delivery date a given number of business days after the order, and see how long it really takes once weekends and holidays intervene.
Managing payroll cut-off and payment dates
Count the business days between the attendance cut-off and the pay date, and check that the processing schedule holds up even in a month broken by holidays.
Working out a project’s actual working days
Count how many days are genuinely available between two dates, and judge whether the schedule is realistic for the amount of work.
Gauging response deadlines in administrative procedures
Turn a rule such as “a reply within N business days of submission” into the actual date, with weekends and public holidays taken out.
Terms about business days
- Business day
- Generally, a day on which ordinary work is done — that is, any day other than a Saturday, Sunday or public holiday. There is no single statutory definition; the exact scope is settled by the custom of each industry or company.
- Public holiday
- A holiday laid down in Japan’s Act on National Holidays. This tool treats every holiday in the data published by the Cabinet Office as a non-working day.
- Substitute holiday
- The arrangement whereby, when a public holiday falls on a Sunday, the next following weekday becomes a holiday. This tool counts substitute holidays as non-working days in the same way as public holidays.
- Citizens’ holiday
- The arrangement whereby a weekday sandwiched between two public holidays becomes a holiday itself — part of September’s Silver Week is an example. It is included in the holiday data and treated as a non-working day.
- Statutory day off
- The day off that Japan’s Labour Standards Act obliges an employer to grant — one day a week, or four days in four weeks. Which day of the week a company designates for it varies from company to company.
- Contractual day off
- A day off a company sets for itself in its work rules, over and above the statutory one. Many Japanese companies make Saturday the contractual day off and Sunday the statutory one.
- Calendar days
- A plain count of days on the calendar, taking no account of weekdays or holidays. The wider the gap from the business-day count, the more weekends and holidays the period contains.
Frequently Asked Questions
Side Note — There Is No Legal Definition of a "Business Day"
It may come as a surprise, but the term "business day" has no single, unified legal definition. Individual laws such as banking regulations or labor law each define "holidays" within their own context, but there is no general law that defines "business day" across the board — in practice, the common understanding of "a day excluding weekends and holidays" has simply formed through business and industry custom.
Expressions like "within X business days" in contracts and invoices are deliberately distinguished from calendar days. If a period were fixed at "within 30 calendar days," a long holiday stretch falling in between could drastically shrink the actual working time available — converting the period to business days is meant to smooth out the effect of holidays and weekends.
The financial industry also uses an even narrower concept: "bank business days," based on the days a bank's counters are open. This can lead to subtly different rules than the general "excluding weekends and holidays" definition — for example, in how brokerage closures or New Year's Eve (December 31 in Japan) are treated.