Japanese nengo era year calculator
Find the Japanese era year for any date since 1868: 2024-06-15 is Reiwa 6 (令和6年), and switchover days are exact, so 30 April 2019 is still Heisei 31. Covers Meiji, Taisho, Showa, Heisei and Reiwa. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Date
- 2024-06-15
- Year
- 2,024
- Month
- 6
- Day
- 15
- Era
- Reiwa
This Japanese nengo era year calculator takes an explicit ISO calendar date in YYYY-MM-DD form and returns the modern Japanese imperial era name and year for that day — Reiwa, Heisei, Showa, Taisho, or Meiji — with the nengo year number used on official documents, bank forms, and school records in Japan. The mapping is fully deterministic: five fixed official era start dates define the ranges, and the year within an era is simply the Gregorian year minus the era start year plus one. Boundary days are resolved exactly, so 30 April 2019 is Heisei 31 while 1 May 2019 is Reiwa 1, and 7 January 1989 is Showa 64 while 8 January 1989 is Heisei 1.
What a Japanese nengo year is and what this calculator returns
Japan still labels years with nengo, the imperial era name and a year number that restarts at one when a new emperor ascends and a new era is proclaimed. In everyday speech and on many official forms you will see Reiwa 6 rather than 2024, Heisei 31 rather than 2019 before May, or Showa 64 for the first week of 1989.
This calculator accepts one required field, an ISO calendar date, validates that it is a real Gregorian day, and returns the era in English and Japanese kanji, the romaji spelling, the integer nengo year, the era start date used as the cutoff, a short English label such as Reiwa 6, a Japanese label such as 令和6年, and a one-line message that states the mapping.
The five modern eras covered are Meiji from 23 October 1868, Taisho from 30 July 1912, Showa from 25 December 1926, Heisei from 8 January 1989, and Reiwa from 1 May 2019. Dates strictly before the Meiji start are rejected because pre-Meiji era tables and historical calendar reforms are out of scope for this tool. Western weekday names, Chinese zodiac animals, and Hijri conversion live in other capabilities; this page answers only the modern Japanese nengo era and year for a validated ISO date.
How the ISO date is read and how era boundaries stay reproducible
The string must be exactly four digits, a hyphen, two digits, a hyphen, and two digits; leading spaces are trimmed, but scientific notation, slashes, and day-month-year European forms are rejected with a clear message so a bad cell does not become the wrong era. After the pattern check, the year, month, and day are parsed as integers, the month must lie between one and twelve, and the day must fit the real length of that month including Gregorian leap February.
The resulting components are re-emitted as a canonical zero-padded ISO string so 2024-6-15 never sneaks through as a partial match. The first era whose start is less than or equal to the input date, walking from Reiwa back to Meiji, wins. The nengo year is then gregorian year minus era start year plus one, which yields Reiwa 1 for every day from 1 May 2019 through 31 December 2019, Reiwa 6 for all of 2024, and Heisei 31 only for 1 January 2019 through 30 April 2019.
Where Japanese nengo conversion fits in documents, product, and software
Government forms, bank applications, school transcripts, and medical records in Japan often expect a nengo year rather than a four-digit Gregorian year, so localization and compliance products need a stable mapping from an explicit civil date to era plus year. Genealogy and family-history tools convert historical Gregorian dates on Japanese records into Meiji, Taisho, or Showa labels for readable timelines.
Teachers and cultural-education apps use the calculator to show how mid-year era changes create two labels in the same Gregorian year, and to demonstrate why a birthday on 30 April 2019 is still Heisei while the next morning is Reiwa. Event planners and marketers building Reiwa anniversary copy can confirm the correct year number before printing materials. Pair it with other free deterministic date helpers when you are assembling a small lab of calendar utilities for teaching, compliance, or product features.
What you can do with it
Official form and bank date fields
Convert a Gregorian ISO date to Reiwa or Heisei year labels expected on Japanese government, school, and banking forms.
Genealogy and cultural timelines
Label historical dates with Meiji, Taisho, or Showa years for readable family histories and educational timelines.
FAQ
What does the Japanese nengo era year calculator cost?
It is free in your browser on this page.
Which eras are supported?
The five modern eras with fixed official starts: Meiji (1868-10-23), Taisho (1912-07-30), Showa (1926-12-25), Heisei (1989-01-08), and Reiwa (2019-05-01).
What if my date is before Meiji?
Pre-Meiji eras are out of scope; the earliest accepted day is 1868-10-23.
Why is 30 April 2019 Heisei 31 but 1 May 2019 Reiwa 1?
Reiwa began on 1 May 2019, so every day up to 30 April still belongs to Heisei, which was then in its 31st year. The calculator uses the exact start date of each era, not just the year.
How is the year within an era worked out?
Take the Gregorian year, subtract the year the era began and add one. Reiwa started in 2019, so 2024 is Reiwa 6, and the first, partial year of each era counts as year 1.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/date/japanese-nengo-year \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"date":"2024-06-15"}'const res = await fetch("https://api.kit.forhosting.com/date/japanese-nengo-year", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"date": "2024-06-15"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/date/japanese-nengo-year",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"date": "2024-06-15"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/date/japanese-nengo-year", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"date":"2024-06-15"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"date":"2024-06-15"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/date/japanese-nengo-year", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"date": "2024-06-15"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "date.japanese_nengo_year",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
year_min | 1868 |
year_max | 9999 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
What a Japanese nengo year is and what this calculator returns
There is no remote calendar service and no sampling of folklore: either the date validates and the era is fully determined, or the request fails with invalid_input. Rejected cases include a missing date, a non-string token, a string that is not exactly YYYY-MM-DD, impossible days such as 31 April or 29 February in a non-leap year, and any day before 1868-10-23.
How the ISO date is read and how era boundaries stay reproducible
The preferred field name is date, but aliases iso_date, value, and gregorian are accepted so spreadsheets, query strings, and typed forms can reuse the same contract without renaming columns. Pair the free browser run on this page with the priced API when you need the identical label inside an automated pipeline without re-implementing era cutoffs yourself.
Where Japanese nengo conversion fits in documents, product, and software
On this page the work runs entirely in your browser; through the API each successful conversion costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — matches the rest of the KIT tier-A catalog and lets you move from a one-off trivia check to multi-year document pipelines without changing the mathematical result.
Integration use cases
Era boundary fixtures for tests
Assert known cutovers such as 2019-04-30 → Heisei 31 and 2019-05-01 → Reiwa 1 in CI without external calendar APIs.
Technical questions
How is the nengo year number computed?
After the era is selected by comparing the ISO date to the fixed start table, nengo_year = gregorian_year − era_start_year + 1. Example: 2024 is Reiwa 6.
Does the result depend on my timezone?
No. The date is treated as a pure UTC calendar day (YYYY-MM-DD) with no time-of-day and no host-clock Date object.