About SunAngle
Sun and solar calculators that compute rather than look up, and that show their working.
Why this exists
Most golden hour tools apply a fixed offset to sunset. That is roughly right in London in April and badly wrong in Singapore or northern Norway, where the sun approaches the horizon at a completely different angle. Most solar calculators set panel tilt to your latitude, which ignores how much of your light arrives scattered through cloud.
Both shortcuts exist because the correct calculation is more work. We did the correct calculation.
How it works
Sun position comes from the NOAA algorithm and needs no data at all — a latitude, longitude and date are enough, for any point on Earth and any year. Solar irradiance comes from NASA's 30-year climate averages, baked into the site as static data.
Everything runs in your browser. There is no account, no tracking of what you calculate, and no server receiving your location. You can read the full methodology, including what we deliberately do not model.
On accuracy
Astronomical code fails quietly: a wrong answer still looks like a plausible time. So the calculations here are verified against independent sources across latitudes from the equator to 78° north, and the solar yields are checked against published industry figures. That process caught two genuine bugs before launch — and one case where the reference source we were checking against turned out to be the inaccurate one.
How this site is funded
SunAngle is free and supported by display advertising. Ads never influence the numbers. See the privacy policy for how advertising cookies work.
Feedback
Found a figure that looks wrong, or want a city added? Get in touch.