Daylight Calculator
Estimate daylight hours
How to Use This Calculator
Enter your latitude (negative for southern hemisphere) and the day of year. Click Calculate to estimate daylight hours using a standard declination model.
Formula
H₀ = arccos(-tan φ · tan δ)
Daylength ≈ 2 · H₀ (deg) / 15
Declination δ ≈ 23.44° · sin(2π(284 + N)/365), where N is the day of year.
Frequently Asked Questions
Is this precise?
This is an approximation. It ignores atmospheric refraction and equation of time. It’s good for quick estimates.
What about polar regions?
The model caps at 0 or 24 hours to handle polar night and midnight sun cases.