Convert Japanese era dates
Japanese forms, contracts and certificates are dated by era. Getting one wrong by a year is easy, because eras change mid-year rather than in January.
- Runs entirely in your browser
- Works offline
- No upload
- No sign-up
- No watermark
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How it works
- Type a Western date, or pick an era and a year.
- Both sides update together, with the day of the week.
- Use the second panel to count working days between two dates.
Why nothing is uploaded
Every operation on this page is done by code running inside your browser tab, using the same engine that renders web pages. The file is read from disk into your tab’s memory, transformed there, and written back out as a download. It is never sent anywhere — not to us, not to a third party.
Verify it yourself
- Open your browser’s developer tools (F12) and select the Network tab.
- Load your file and run the tool.
- The only requests you will see fetch the tool’s own code — and, for a few heavy tools, their open-source engine from a public CDN — plus one small page-view ping to loreatec.jp (page address and title, nothing more). None of them carry your file.
Frequently asked questions
Why is 1989 both Shōwa and Heisei?
Because eras change on the day of the change, not on 1 January. The first seven days of 1989 are Shōwa 64 and the rest is Heisei 1. This tool uses the exact change dates, which is where most conversion tables go wrong.
What is 元年?
The first year of an era, written 元年 rather than 1年. It is not decorative — official documents use it, and a form filled in with 令和1年 looks wrong to a Japanese reader.
Are the holiday dates reliable?
The fixed-date holidays and the “Happy Monday” holidays (those moved to a Monday to make a long weekend), yes. The spring and autumn equinox holidays depend on the sun’s position and can fall on a different day from year to year; the government only confirms them in February of the previous year, so for future years they are a well-founded prediction rather than an announced fact.
Does it know about older holiday rules?
Yes, for the main ones. The Emperor’s Birthday was 29 April, then 23 December, and is 23 February from 2020; Marine Day and Sports Day moved to Mondays in 2003 and 2000; Mountain Day only exists from 2016. Past dates use the rule that applied then.