Explore day length and how it changes through the year.
Compare daylight through the year. Enter coordinates and the UTC offset that applies on your chosen date.
Enter your field location to calculate.
Method, assumptions and field use
These are estimates for an unobstructed horizon at sea level using NOAA’s approximate solar-position equations. The calculation samples the chosen local calendar day and refines altitude crossings. Sunrise and sunset use a solar-centre altitude of −0.833°, allowing approximately for refraction and the Sun’s radius. Civil, nautical and astronomical twilight use −6°, −12° and −18° respectively.
Golden hour here is defined as the Sun’s centre between −4° and +6° altitude, a planning convention rather than a guarantee of photographic light. Clouds, terrain, buildings and elevation affect what you see. Allow several minutes of timing margin, and more at high latitudes. Do not use these estimates for navigation or safety-critical decisions.
Dates are limited to 1900–2100. All times show the entered fixed UTC offset; the tool does not look up time zones or apply daylight saving automatically. Monthly daylight comparisons use the 15th of each month and the same offset. A window touching midnight may continue on the adjacent date. Calculations stay in your browser.
Instructions
- Choose Date for your planned visit.
- Enter Latitude (north positive) and Longitude (east positive). Use decimal degrees and minus signs for south or west.
- Set UTC offset in hours for that date, including daylight saving, then select Calculate.
- Use Print result or Download text after checking the location and times.
Understanding your results
The result compares the selected day with monthly daylight estimates. The monthly values use the 15th, so they show a broad seasonal pattern rather than an exact diary of every day. Day length describes the Sun above the model horizon, not hours of sunshine.
What to do if the monthly comparison differs from your weather experience
Cloud cover does not change calculated daylight. Check the latitude and remember that buildings, hills and tree cover can shorten the light you experience at your site.
Using this tool in your browser
This tool handles your entries in your browser with JavaScript enabled and does not save them automatically. Use the download or print controls described in the instructions to keep a copy before closing or reloading the page. On a phone, your browser controls where downloads go and which print options are available.
Summary
Compare the seasons to choose a useful daylight window for your next outing.