Days Between Dates & Days Later Calculator
Calculate the number of days, weeks, and business days between two dates. Or find what date is N days from now. Includes Japan public holidays for accurate business day counts.
Common Day Calculations in Japan
| Purpose | Days | Notes |
|---|
| Baby’s 100-day celebration (Okuizome) | 100 days after birth | Some regions: 110 or 120 days |
| Tax filing period (Kakutei Shinkoku) | Feb 16 – Mar 15 (28 days) | Annual deadline |
| Maternity leave (statutory) | 42 days before + 56 days after birth | 98 days before for multiple births |
| Childcare leave (maximum) | Until child turns 2 | Extendable by agreement |
| Paid leave expiry | 2 years (730 days) from grant date | Labor Standards Act Art. 115 |
| Credit card payment cycle | 20–35 days after closing date | Varies by issuer |
| Real estate closing | 1–3 months (30–90 days) | Including mortgage approval |
Why Day Counting Matters in Japan
Calculating the number of days between dates is essential in many everyday and business situations in Japan. From confirming tax filing deadlines (kakutei shinkoku runs from February 16 to March 15 every year) to planning baby milestone celebrations, accurate day counts help you stay organized. This tool goes beyond simple subtraction — it shows weeks, remaining days, and business days using official Japanese holiday data, making it ideal for contract deadlines, project management, and personal planning.
Japan has 16 national public holidays per year, more than most other countries. Combined with the tradition of taking extended leave during Golden Week (late April to early May), Obon (mid-August), and New Year (late December to early January), business day calculations in Japan require careful attention to the calendar. A "10 business days" deadline that spans Golden Week, for instance, may translate to nearly three calendar weeks.
Finding a Date N Days From Now
Need to know what date is 100 days from now, or 30 days ago? The "Calculate Future Date" tab handles this instantly. Enter any start date and a number of days (positive for future, negative for past) to get the result with the day of the week. If the resulting date happens to be a Japanese public holiday, the tool displays the holiday name as well — helpful for scheduling appointments or deliveries around official days off.
Common uses include calculating a baby's 100-day celebration (Okuizome), checking warranty expiry dates, counting down to important deadlines, and planning project milestones. The quick preset buttons let you instantly check common intervals like 1 week, 30 days, 100 days, and 1 year.
Frequently Asked Questions
What date is 100 days from today?
Use the "Calculate a Future Date" tab of this tool to find what date is 100 days from today. Enter today as the start date and type "100" in the days field. For example, 100 days after January 1, 2026 is April 11, 2026 (Saturday). This is useful for tracking deadlines, warranty expirations, and milestone dates.
How do I calculate days between two dates?
The days between two dates is calculated as "end date minus start date". For example, from January 1, 2026 to March 31, 2026 is 89 days. Use the "Calculate Period" tab and enter both dates to get the total days, weeks, remaining days, and business days automatically. You can also choose whether to include the start date in the count.
How are business days calculated in Japan?
Business days in Japan exclude weekends (Saturday and Sunday) and all national public holidays. Japan has 16 national holidays per year, including Golden Week (late April to early May) and New Year's holidays. This tool uses official Japanese holiday data to calculate accurate business day counts, including substitute holidays (furikae kyūjitsu).
When is a baby's 100-day celebration in Japan?
In Japan, Okuizome (お食い初め) is a traditional ceremony held on the 100th day after a baby's birth. Use the "Calculate a Future Date" tab, enter the birth date, and type "100" to find the celebration date. Note that some regions celebrate on the 110th or 120th day instead.
How do I check warranty or expiry dates?
Use the "Calculate a Future Date" tab to check warranty or expiry dates. Enter the purchase or start date, then enter the warranty period in days (e.g., 365 for one year). The tool instantly shows the exact expiry date and day of the week. If the result falls on a Japanese public holiday, the holiday name is displayed too.