Date Calculator | Days after, before, and between two dates
Calculate dates before or after a chosen day, measure the difference between two dates, and count business days while skipping weekends or Japanese public holidays from bundled data. It is useful for deadlines, contracts, travel planning, and quick schedule checks in the browser.
Result
2026/7/16 (Thu)
Base date：2026/6/16 (Tue)
Calculation：30 days after
What you can do with Date Calculator
- Find a date N days after a chosen day, such as 7, 30, or 100 days later, with weekday labels.
- Find dates before a chosen day, such as one week or one month before a deadline.
- Measure contract lengths, trip lengths, event spans, and other gaps between two dates, including a separate total that counts the start date.
- Count business days while skipping weekends only, or weekends plus Japanese public holidays from bundled data.
- For before/after and business-day results, copy a sentence, plain date, weekday label, or ISO date. For date differences, copy the summary sentence.
- Share or bookmark calculations via URL query parameters when you change inputs.
How to use
- Pick a tab: Before/After, Date difference, or Business days.
- Enter dates and numbers; results update automatically as you type.
- For differences, enter a start date and an end date. The result shows both the standard difference and the total when the start date is counted. If the end date is before the start date, fix the dates to see a result.
- For business days, pick direction and whether to skip only weekends, weekends and holidays, or no days.
- Use copy buttons for the format you need, or Reset to defaults.
How to read the results
On the Before/After tab, the result shows the calculated date with its weekday. Copy buttons let you copy a sentence, plain date, weekday label, or ISO date.
On the Date difference tab, the result shows the gap between the start and end dates, plus a separate total that counts the start date.
On the Business days tab, the result reflects how many business days were added or subtracted based on your weekend and holiday skip settings.
Ways to use it
Deadlines
Calculate dates before or after a chosen day to confirm submission, return, or due dates with weekday labels.
Contracts and validity windows
Measure the number of days between two dates to check contract length, validity periods, or warranty windows.
Trips and events
Count the days in a travel schedule or event span when you need a quick schedule overview.
Rough business-day planning
Use business-day mode to estimate delivery, payment, or planning dates while skipping weekends or Japanese holidays.
How input data is handled
- Calculations are date-only (no time zones).
- Japanese holidays come from bundled data derived from an official-style CSV. Years outside the covered range do not apply holiday skips.
- Do not rely on this tool alone for legal cutoffs—confirm with your own calendar and policies.
FAQ
- Can I calculate a date N days after today?
- Yes. Set the base date to today and enter the number of days.
- Can I calculate a date N days before?
- Yes. Switch direction to “before” and enter the number of days.
- Can I measure the days between two dates?
- Yes. Use the Date difference tab and enter the start and end dates. The result also shows the total when the start date is counted.
- Do results include weekdays?
- Yes. Results show weekday names, and copy formats include weekday-labeled text.
- Does it work on phones?
- Yes. Use it from a mobile or tablet browser.
- Are my dates saved?
- No. Everything is calculated locally in your browser and is not sent to a server.
- Can business-day mode skip holidays?
- Yes. Choose weekends and Japanese holidays to skip dates from the bundled holiday list (year range limits apply).
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