pray_calc_dart #

Islamic prayer times for Dart and Flutter. Pure Dart port of pray-calc, implementing the MCW seasonal model and dynamic twilight angles. Uses nrel_spa for the NREL Solar Position Algorithm.

Installation #

dependencies:
  pray_calc_dart: ^1.0.0

Quick Start #

import 'package:pray_calc_dart/pray_calc_dart.dart';

void main() {
  final date = DateTime(2024, 3, 15);
  final times = getTimes(date, 40.7128, -74.0060, -5.0);

  print('Fajr:    ${formatTime(times.fajr)}');
  print('Sunrise: ${formatTime(times.sunrise)}');
  print('Dhuhr:   ${formatTime(times.dhuhr)}');
  print('Asr:     ${formatTime(times.asr)}');
  print('Maghrib: ${formatTime(times.maghrib)}');
  print('Isha:    ${formatTime(times.isha)}');
  print('Qiyam:   ${formatTime(times.qiyam)}');

  // Or get them already formatted.
  final f = calcTimes(date, 40.7128, -74.0060, -5.0);
  print('Isha: ${f.isha}  Midnight: ${f.midnight}');
}

Comparing against a specific authority #

The default is the dynamic method. When you need to match a published timetable, ask for every method at once and pick the one you need:

final all = calcTimesAll(DateTime(2024, 3, 15), 40.7128, -74.0060, -5.0);

print(all.fajr);                 // dynamic method
print(all.methods['MWL']![0]);   // Muslim World League Fajr
print(all.methods['ISNA']![1]);  // ISNA Isha

for (final m in kMethods) {
  print('${m.id.padRight(8)} ${m.name}');
}

A method that cannot reach its depression angle where and when you asked reports 'N/A' rather than a substituted time — above roughly 48.5 degrees the sun stops reaching 18 degrees below the horizon in summer, so an 18-degree method simply has no answer there. That is the point of the map: it shows you which methods are applicable. To get a displayable time in those conditions, use highLatitudeRule with the primary times.

API #

Full API documentation, guides, and examples are in the wiki.

Core functions #

Dynamic Angle Algorithm #

Fixed-angle methods (ISNA 15 degrees, MWL 18 degrees) produce inaccurate Fajr times at latitudes above 45 degrees N/S. The dynamic method adapts the depression angle based on season, latitude, Earth-Sun distance, and local atmospheric conditions.

Result: approximately 18 degrees at the equator, approximately 12-14 degrees at 50-55 degrees N in summer. Matches observational data from the Moonsighting Committee Worldwide.

High latitudes #

Above roughly 48.5 degrees the sun stops reaching 18 degrees below the horizon in summer, and inside the polar circles it stops rising or setting at all for weeks. There is then no observable dawn or nightfall, so Fajr and Isha have no calculable time.

By default this package reports them as absent (double.nan, formatted "N/A") rather than substituting a value, because every substitution is a juristic position rather than an astronomical result:

final t = getTimes(DateTime.utc(2026, 6, 21), 78.22334, 15.64689, 1.0);
// t.fajr.isNaN == true
// t.provenance.fajr == TimeSource.unavailable
// t.dhuhr and t.asr are still real times

Six opt-in rules are available via highLatitudeRule:

final t = getTimes(
  DateTime.utc(2026, 6, 21), 78.22334, 15.64689, 1.0,
  highLatitudeRule: HighLatitudeRule.aqrabAlBilad,
);
// t.provenance.fajr == TimeSource.aqrabAlBilad

The three night-proportion rules divide the span between sunset and sunrise, so inside the polar circles they have nothing to measure and correctly decline to invent a time. Only the two nearest-substitution rules cover those latitudes.

provenance names the origin of Fajr and Isha on every result, so a substituted time is never mistaken for a computed one.

Dhuhr and Asr remain available every day at every latitude: the sun crosses the local meridian even on days it never rises. Inside the polar circles during winter that crossing happens below the horizon, so those times are astronomically real but not observable.

Twilight angle range #

The dynamic angle is clamped to 10-22 degrees. Above roughly 70 degrees it sits at the 10-degree floor, outside the latitude span the Moonsighting Committee data was fitted to. Treat results there as the edge of the model's validated range.

Compatibility #

Dart SDK 3.7.0+. Works in Flutter (iOS, Android, Web, Desktop), Dart CLI, and server-side Dart. Single dependency: nrel_spa.

Related #

• pray-calc - TypeScript/JavaScript version (npm)
• nrel-spa - Standalone NREL SPA for JavaScript
• qibla - Qibla direction calculator

Acknowledgments #

The Solar Position Algorithm is based on:

Reda, I. and Andreas, A. (2004). Solar Position Algorithm for Solar Radiation Applications. NREL/TP-560-34302. DOI: 10.2172/15003974

The MCW seasonal model is based on the work of the Moonsighting Committee Worldwide (Khalid Shaukat).

License #

MIT. The NREL SPA implementation carries its own terms (see LICENSE for details).