Sunrise Sunset Calculator — Sun Times by City or Coordinates

Date & Time

A sunrise sunset calculator computes sunrise, sunset, solar noon, and day length from a date and latitude/longitude using the NOAA solar position equations.

Sunrise Sunset Calculator

Runs in this browserNOAA±1–2 min

Uses the NOAA solar equations with standard atmospheric refraction (0.833°); accuracy is typically ±1–2 minutes. There is no geolocation: coordinates you enter stay in your browser and are never sent or stored.

City preset

Date

Latitude (°)

Longitude (°)

UTC offset (hours)

Sunrise

—

What is it

Sunrise and sunset are the moments the Sun's center crosses the horizon, computed with a zenith angle of 90.833° to account for standard atmospheric refraction (0.833°). This tool implements the NOAA solar calculation equations (equation of time, solar declination, hour angle) directly in your browser, with coordinate presets for major Korean cities (Seoul, Busan, Incheon, Daegu, Daejeon, Gwangju, Ulsan, Jeju) and manual latitude/longitude input. Typical accuracy is within ±1–2 minutes; altitude, terrain, and actual atmospheric conditions can add a few more minutes of difference. There is no location auto-detection: only coordinates you type are used, and they are never sent to or stored on a server.

hour angle H = acos(cos 90.833° ÷ (cos φ × cos δ) − tan φ × tan δ) · sunrise (min, UTC) = 720 − 4 × (longitude + H) − eqtime · sunset (min, UTC) = 720 − 4 × (longitude − H) − eqtime (φ = latitude, δ = solar declination)

How to use

1Pick a city preset or enter latitude and longitude manually.
2Set the date and UTC offset (Korea is +9).
3Press calculate to see sunrise, sunset, solar noon, and day length.

Reference

Sunrise Sunset Calculator — Sun Times by City or Coordinates Reference
Location	Date	Sunrise	Sunset	Day length
Seoul (37.57, 126.98)	2026-01-01	07:47	17:23	9h 37m
Seoul (37.57, 126.98)	2026-06-21	05:11	19:56	14h 46m
Busan (35.18, 129.08)	2026-01-01	07:32	17:21	9h 50m

Sources & standards

NOAA Solar Calculator - NOAA Global Monitoring Laboratory
NOAA Solar Calculation Details (sunrise/sunset equations) - NOAA Global Monitoring Laboratory

FAQ

How accurate are the sunrise and sunset times?

Usually within ±1–2 minutes of NOAA reference values. The calculation assumes standard atmospheric refraction of 0.833°, so real temperature, pressure, elevation, and terrain (mountains, buildings) can shift the observed times by a few more minutes.

Does this tool detect my location automatically?

No. For privacy there is no geolocation: you choose a city preset or type latitude/longitude yourself, and the coordinates are used only in your browser — never sent to or stored on a server.

Is daylight saving time applied?

No. Local times use the fixed UTC offset you enter. For regions with DST, select the offset in effect on that date (for example US Eastern summer is −4).