Taiwan Minguo (ROC, since 1912) years and the Chinese lunar calendar converted to Gregorian dates locally - and back again. No upload.
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
In Taiwan, alongside the Gregorian calendar, two other systems appear in daily life: the Minguo (ROC) year (year 1 is 1912, the founding year of the Republic of China) on official documents, contracts and packaging dates, and the traditional Chinese lunar calendar for holidays such as Chinese New Year, the Lantern Festival or the Mid-Autumn Festival. This tool converts between all three systems - whichever one you start from, you always get all three date forms.
The conversion runs entirely locally in your browser, in pure JavaScript - nothing is uploaded and nothing is stored. The ROC year is a simple shift (ROC year equals the Gregorian year minus 1911) and converts exactly in both directions. The lunar calendar, by contrast, has no fixed formula: month lengths and leap months follow the actual moon phase and sun position and do not repeat in a simple pattern. The forward direction (Gregorian to lunar) therefore uses the astronomical lunar-calendar calculation built into the browser; the backward direction searches among those same values for the matching date instead of guessing its own approximation - so both directions rest on the same source.
An honest note: the ROC year is supported from year 1 (1912) onward; earlier dates are not intended for this calendar. For the lunar calendar, every entry is checked against the actual computation - a leap month that never occurred in the chosen year, or a day a shorter lunar month does not have, is honestly reported as invalid instead of showing a wrong date.
| Input formats | Form inputs (no file) |
|---|---|
| Processing | Locally in your browser (JavaScript) |
| File upload | None |
Limitations: The ROC year is supported from year 1 (1912) onward - a simple, exact shift. The lunar calendar relies on the astronomical calculation built into the browser; a leap-month or day combination that never occurred in the chosen year is honestly reported as invalid instead of showing a wrong date. A very old browser without full calendar support likewise shows an honest dash instead of a wrong result.
No. The conversion runs entirely locally in the browser (pure JavaScript); nothing is sent or stored.
ROC year equals the Gregorian year minus 1911. The other way round: Gregorian year equals the ROC year plus 1911. So ROC year 1 is 1912.
Because its months follow the actual moon phase and leap months are inserted irregularly to keep pace with the seasons - unlike the ROC year, there is no simple formula for this.
The tool shows an honest dash instead of a wrong date - for example for a leap month that never occurred in the chosen year.
Not for the ROC year, which starts at year 1 (1912). The Gregorian calendar and the lunar calendar work independently of that for earlier dates too.
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