What formula does this tool use?

The tool uses the astronomical sunrise hour angle formula: omega = arccos(-tan(latitude) * tan(declination)). Solar declination is computed via the Spencer formula using the day of year. Daylight duration equals 2 * omega (in radians) converted to hours.

How accurate are the sunrise and sunset times?

The times are approximate solar times (not adjusted for your local timezone or longitude offset within your timezone). They assume you are at the central meridian of your timezone. For precise local times, apply your UTC offset and longitude correction manually.

What happens at extreme latitudes near the poles?

Above ~66.5° latitude (Arctic/Antarctic Circle), there are dates with 24 hours of daylight (midnight sun) or 0 hours (polar night). The tool correctly displays these as "Midnight Sun" or "Polar Night" when the sun never sets or never rises.

Solar noon is the moment each day when the sun reaches its highest point in the sky and is exactly due south (in the Northern Hemisphere) or due north (in the Southern Hemisphere). It is always exactly halfway between sunrise and sunset in this approximation.

Why does the equator have roughly 12 hours of daylight year-round?

At 0° latitude, the sunrise hour angle always evaluates to nearly 90° regardless of the solar declination, giving approximately 12 hours of daylight every day. Small variations of about 15–20 minutes occur due to the eccentricity of Earth's orbit.

Can I use this for a location in the Southern Hemisphere?

Yes. Enter a negative latitude (e.g., -34 for Sydney, Australia). The seasons are reversed — summer solstice in December gives maximum daylight, and June gives minimum daylight.

Daylight Length Calculator

Name: Daylight Length Calculator
Availability: InStock
Author: Nham Vu

Enter your latitude and a date to instantly see total daylight hours, approximate sunrise and sunset times, and a full 12-month daylight chart.

Location & Date

Latitude (-90 to +90)

Positive = Northern Hemisphere, negative = Southern

Quick Presets

Date

Enter your latitude and a date, then click
Calculate Daylight.

Summary

Enter your latitude and a date to instantly see total daylight hours, approximate sunrise and sunset times, and a full 12-month daylight chart.

How it works

Enter your geographic latitude in decimal degrees (-90 for South Pole, +90 for North Pole).
Select the date you want to analyze.
The tool calculates the solar declination angle from the day of year using the Spencer approximation.
It then computes the sunrise hour angle (omega) to determine the fraction of the day that is sunlit.
Daylight duration, sunrise, solar noon, and sunset times are displayed in hours and minutes.
A bar chart shows the daylight duration for every month of the selected year.

Use cases

Plan outdoor photography sessions by knowing exact daylight windows.
Estimate solar panel energy output for a given location and season.
Understand why days are longer in summer and shorter in winter.
Compare daylight hours between different latitudes around the world.
Plan travel activities that require daylight, such as hiking or sightseeing.
Calculate approximate sunrise and sunset times for any date and location.
Determine the best month to visit a destination for maximum daylight.
Study the effect of latitude on seasonal daylight variation.

Frequently Asked Questions

Last updated: 2026-06-15 · Reviewed by Nham Vu