Handy Convert

How to use

1. Choose Date, Time, or Text from the main categories.
2. Under Date, choose date difference, date offset, age/elapsed period, or Gregorian/Japanese era conversion and enter the required values.
3. Under Time, add cities to the world clock or choose source/destination cities and a local date-time for time-zone conversion.
4. Under Text, paste a string and review hiragana, katakana, half-width kana, or selected full-/half-width conversion results.
5. Copy the result you need. Only a small set of UI preferences, such as added world-clock cities, may be stored locally.

Supported

• Date: date differences, date offsets, age/elapsed periods, and Gregorian/Japanese era conversion for Meiji, Taisho, Showa, Heisei, and Reiwa.
• Time: world clock plus date-time conversion using browser-provided IANA time-zone data, including handling of nonexistent and repeated local times around DST changes.
• Text: simultaneous hiragana, katakana, and half-width kana output, plus selective full-/half-width conversion for letters, numbers, symbols, and spaces.
• Storage: entered dates, date-times, and text are not persisted. The UI language, last category, and added world-clock cities may be stored in LocalStorage.

Limitations and notes

• Business-day counts exclude Saturdays and Sundays only; holidays and country-specific working calendars are not included.
• Age and elapsed-period results are calendar calculations and are not intended as legal age determinations.
• Japanese era conversion covers dates from January 1, 1873 onward and does not handle historical calendars such as the old lunar calendar.
• Time-zone conversion uses the IANA data bundled with the browser, so very old browsers may have outdated rules. The world clock is based on the device clock.
• Full-/half-width conversion changes only the selected character classes and intentionally preserves unrelated Unicode characters such as kanji and emoji.