Sunrise, Sunset & Civil Twilight Calculator
This sunrise and sunset calculator gives sunrise, sunset, civil twilight and day length for any place and date.
Related guides
- Zulu Time (UTC) in Aviation: converting sunrise and sunset times between UTC and local time
- VFR Fuel Reserve Rules: why day and night VFR reserves differ under FAA rules
Sunrise, sunset and twilight explained
Sunrise and sunset are when the top edge of the Sun crosses the horizon. Civil twilight is the period when the Sun is less than 6° below the horizon: there is still enough natural light for most outdoor activity. Photographers call the time around it the golden and blue hours, and pilots use it to define night.
How to use it
- Enter latitude and longitude in decimal degrees, or use your location.
- Pick a date.
- Choose the time zone to show local times.
- Read sunrise, sunset, civil twilight, solar noon and day length.
Method and calculation
The calculator uses the NOAA solar position equations (equation of time and solar declination) with the standard −0.833° altitude for sunrise and sunset, which allows for atmospheric refraction and the Sun’s radius, and −6° for civil twilight. Results are typically within about a minute for latitudes below 70°.
Worked example and practical notes
London (51.5072° N, 0.1276° W) on 21 June: sunrise about 04:43 and sunset about 21:21 British Summer Time, giving about 16 h 38 min of daylight.
Accuracy and practical tips
For logging night time, the FAA defines night as the period between the end of evening civil twilight and the beginning of morning civil twilight. Night currency for carrying passengers (14 CFR 61.57(b)) uses one hour after sunset to one hour before sunrise. EASA and UK rules use civil twilight. Terrain and buildings can hide the Sun well before the calculated sunset.
NOAA Global Monitoring Laboratory solar calculation method. Use official sources for legal and operational timing.
Last reviewed: October 2026
Frequently asked questions
What is civil twilight?
The time when the Sun is between 0° and 6° below the horizon, just before sunrise and just after sunset.
Why is the day length not exactly 12 hours at the equinox?
Refraction and the size of the Sun’s disc make sunrise earlier and sunset later, so day length is a few minutes over 12 hours.
What counts as night for pilots?
For logging, the FAA uses the end of evening civil twilight to the beginning of morning civil twilight. For passenger-carrying currency it is one hour after sunset to one hour before sunrise.
Why can the sun set earlier where I am?
Hills, buildings and trees block the horizon. The calculation assumes a flat, unobstructed horizon.