Japanese era converter
Convert Gregorian and Japanese era dates, or see every era that applies to a year.
Your inputs
Choose your dates and the calculation convention. Results update as you edit.
Calculations run in your browser. Inputs are not saved or sent to analytics.
How it works
- = Gregorian year − Era starting year + 1
- A transition year can have two era labels. Use a full date for a unique result.
- Worked example: The change from Heisei to Reiwa occurred during 2019. Select a full date rather than applying one era label to the entire Gregorian year.
- 2019-04-30 = Heisei 31; 2019-05-01 = Reiwa 1.
Input and formula key
Your result
Complete the inputs to see your result.
Assumptions and limitations
Supported from January 1, 1873 (Meiji 6), when Japan adopted the Gregorian calendar. Era boundaries use full dates. Year one accepts 1 or 元年. Earlier Japanese lunisolar dates are outside scope.
Sources
- NAOJ — Modern Japanese era boundaries Sources reviewed: 2026-10-05
- NAOJ — Japan’s 1873 Gregorian calendar adoption Sources reviewed: 2026-10-05
