Date Calculator
Calculate day shifts, differences, and business days.
Tool
Quick presets
Apply common day counts to the selected base date.
Result
2026/6/9 (Tue)
Base date
2026/5/10 (Sun)
Calculation
30 days after
Weeks
4 weeks and 2 days
What it does
- 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 with optional inclusive counting of the start date.
- Count business days while skipping weekends only, or weekends plus Japanese public holidays from bundled data.
- Copy results as a sentence, plain dates, weekday labels, ISO dates, or weekday-labeled ranges for differences.
- 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 as you type. Quick presets apply common day counts to the selected base date.
- For differences, choose whether the start date counts as day 1. 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.
Examples
- 30 or 100 days after today
- One week before a deadline
- Contract or trip length between two dates
- Days until a birthday (difference tab with today and the target date)
Common uses
- Deadlines
- Contracts and validity windows
- Trips and events
- Rough business-day planning
Notes
- 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.
- Month/year hints are approximate. Do not rely on this tool alone for legal cutoffs—confirm with your own calendar and policies.
FAQ
- 1Can I calculate a date N days after today?
- Yes. Set the base date to today and enter the number of days, or use the quick preset buttons.
- 2Can I calculate a date N days before?
- Yes. Switch direction to “before”, or use the “today minus N days” quick presets when shown.
- 3Can I measure the days between two dates?
- Yes. Use the Date difference tab, enter start and end dates, and choose inclusive or exclusive counting for the start date.
- 4Do results include weekdays?
- Yes. Results show weekday names, and copy formats include weekday-labeled text.
- 5Does it work on phones?
- Yes. Use it from a mobile or tablet browser.
- 6Are my dates saved?
- No. Everything is calculated locally in your browser and is not sent to a server.
- 7What changes when I include the start date?
- Inclusive counting adds one day compared to the simple difference between the two dates.
- 8Can 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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