Methodology, accuracy and sources

What a displayed time means

Sunrise and sunset are calculated at a solar-centre altitude of −0.833°. This standard approximation accounts for the Sun’s apparent radius and average atmospheric refraction. Times are rounded to the nearest minute and refer to the listed coordinate, with a clear, level horizon.

The calculation interpolates a geocentric solar ephemeris, converts it to the observer’s position and solves the altitude crossings within the actual local date. The ephemeris covers 2025–2036; the public date selector keeps a small margin at its ends so adjacent-day comparisons remain available.

Mountains, buildings, cloud and unusual refraction are not modelled. The result is an astronomical planning reference, not a forecast of visibility, weather or access. See the US Naval Observatory’s definitions.

Twilight and photography light

Civil, nautical and astronomical dawn and dusk use the Sun’s centre at −6°, −12° and −18°. A missing crossing is shown explicitly. At high latitudes, there may be no sunrise, no sunset or no astronomical night on a date.

Our golden-hour convention is −4° to +6° in the morning and +6° to −4° in the evening. It is a photography aid, not an official definition of daylight. The site reports no complete interval if its required crossings do not both occur on that local date.

Brahma Muhurta convention

We use a fixed 48-minute muhurta: the displayed interval begins 96 minutes before local sunrise and ends 48 minutes before sunrise. For example, a 6:00 AM sunrise gives 4:24–5:12 AM.

This is the explicit convention used by this calculator. Traditions and panchang calculations can instead divide the night into fifteen parts, which gives a different interval as night length changes. This site does not calculate a personalised ritual schedule or resolve differences between traditions.

Yearly facts and the sun overhead

The longest and shortest days, earliest and latest sunrises and sunsets, and the range of sunrise directions come from the same calculation for every day of the year. They are shown for the current calendar year.

Between the tropics the sun passes directly overhead at solar noon on two days a year. We mark the days on which the noon altitude reaches its local peak above 89.5°; in India these are widely called Zero Shadow Days. The exact moment is local solar noon, also shown on the page.

Time zones and clock changes

Each place has an IANA timezone. The bundled rules are version 2026e; coordinates are checked against the timezone-boundary-builder 2026d polygons. The displayed offset is calculated for each event, including transition days.

A local date is bounded by its two local midnights. Those boundaries need not be 24 elapsed hours apart. Countdown timers use timestamps, and daylight duration sums the actual time above the horizon threshold. Cached city pages expire no later than the next local midnight.

India uses Asia/Kolkata, Indian Standard Time (UTC+05:30), without a seasonal clock change in the current rules.

Future governments can change their rules. The date range is a calculation range, not a guarantee that today’s timezone legislation will remain unchanged.

Place data and population

The starting place names, alternative names and coordinates come from GeoNames, licensed under CC BY 4.0. We have modified names, population records, duplicate handling and two timezone assignments. GeoNames does not endorse this site.

The initial directory uses places with at least 15,000 recorded inhabitants after corrections. Population selects the initial directory; it is not presented as a current population estimate. A town centre is not every address within that town.

Indian checks use the Local Government Directory, Census 2011 district material and the Ministry of Housing and Urban Affairs’ Census 2011 urban-population table. Ambiguous matches are not automatically substituted. Records with unresolved population scope and duplicate municipal components are excluded from the initial city cohort.

Validation and corrections

The engine is checked against dated results from the US Naval Observatory, including India, northern summer and winter, and clock-change dates. The automated comparison allows up to 90 seconds for rounding and model differences. This tolerance is a validation criterion, not a promise about the first visible sunlight at every location.

Found a place-name, timezone or timing problem? Send the place, date and source. We keep an internal correction record and update the affected data and tests.