ethio_calendar

Convert between the Gregorian and Ethiopian (Amete Mihret) calendars, with Amharic and English month/day names, pattern-based formatting, and date arithmetic.

The core is pure Dart with zero dependencies, so it runs everywhere Dart runs — Flutter apps, server-side Dart, and command-line tools.

Features

✅ Accurate Gregorian ⇄ Ethiopian conversion (via Julian Day Number).
✅ Correct leap-year handling — Pagume (the 13th month) has 5 days, or 6 in a leap year (year % 4 == 3).
✅ Correct New Year boundary — Meskerem 1 falls on Sept 11 or Sept 12 Gregorian, depending on whether the following Gregorian year is a leap year.
✅ Amharic (Ge'ez script) and English names for all 13 months and 7 weekdays.
✅ Flexible format() with familiar pattern tokens, in either language.
✅ Comparison operators, difference(), and addDays().

Install

dependencies:
  ethio_calendar: ^0.1.0

Then:

import 'package:ethio_calendar/ethio_calendar.dart';

Quick start

// Gregorian -> Ethiopian
final eth = EthiopianDate.fromGregorian(DateTime(2026, 7, 9));

print(eth);                                   // 2018-11-02
print(eth.format('MMMM d, yyyy'));            // Hamle 2, 2018
print(eth.format('MMMM d, yyyy',
    locale: EthiopianDateLocale.amharic));    // ሐምሌ 2, 2018
print(eth.weekday.english);                   // Thursday
print(eth.weekday.amharic);                   // ሐሙስ

// Ethiopian -> Gregorian
final newYear = EthiopianDate(2017, 1, 1);
print(newYear.toGregorian());                 // 2024-09-11 00:00:00.000

// Arithmetic
final deadline = eth.addDays(45);
print(deadline.difference(eth));              // 45
print(eth < deadline);                        // true

Format tokens

Token	Meaning	Example (Hamle 2, 2018)
`yyyy`	Zero-padded 4-digit year	`2018`
`yy`	2-digit year	`18`
`MMMM`	Full month name (locale-aware)	`Hamle` / `ሐምሌ`
`MM`	Zero-padded month number	`11`
`M`	Month number	`11`
`dd`	Zero-padded day	`02`
`d`	Day	`2`
`EEEE`	Full weekday name (locale)	`Thursday` / `ሐሙስ`

Wrap literal text in single quotes ('Today is' MMMM d), and use '' for a literal quote. Unrecognised characters (/, -, ,, spaces) pass through.

API overview

Member	Description
`EthiopianDate(year, month, day)`	Construct from Ethiopian components (validates ranges).
`EthiopianDate.fromGregorian(DateTime)`	Convert a Gregorian date.
`EthiopianDate.now()`	Today, from the local clock.
`toGregorian()` / `toDateTime()`	Convert back to a Gregorian `DateTime`.
`format(pattern, {locale})`	Format using the tokens above.
`addDays(int)`	Date shifted by a number of days.
`difference(other)`	Signed day count between two dates.
`compareTo`, `< <= > >=`, `==`	Ordering and value equality.
`weekday`	`EthiopianWeekday` (Amharic + English).
`monthInfo`	`EthiopianMonth` (Amharic + English).
`isLeapYear`, `dayOfYear`, `julianDayNumber`	Derived properties.
`isEthiopianLeapYear(year)`	Top-level leap-year test.
`ethiopianDaysInMonth(year, month)`	Days in a given month.

Examples

example/ethio_calendar_example.dart — command-line demo (dart run example/ethio_calendar_example.dart).
example/flutter_app/ — a Flutter app with a date picker converting Gregorian → Ethiopian live.

Accuracy notes

Conversions are anchored to the Julian Day Number and validated against known reference dates (e.g. the Ethiopian Millennium, Meskerem 1 2000 EC = 12 Sept 2007) and a full round-trip sweep of every day from 1900 to 2100. The Ethiopian calendar follows the Amete Mihret (Year of Mercy) era used in everyday Ethiopian civil life.

Contributing

Part of the ethio_dev_kit monorepo. Issues and PRs welcome — please run dart analyze and dart test before submitting.