What is SunCalc?
SunCalc shows the movement of the sun and the phases of sunlight for a chosen day at a chosen place. You set a location on the map and a date, then move the sun along a time slider. The map draws the sun's path for that day and its range across the year, and a data panel lists dawn, sunrise, culmination, sunset, dusk, daylight duration, the sun's altitude and azimuth, and the shadow length of an object of the height you enter.
The site is run by Torsten Hoffmann in Germany, with a German version at sonnenverlauf.de and sister sites for the moon, planets and satellites. Beyond everyday uses such as planning photos or checking sunlight on a building, it is a common geolocation aid in open source research: comparing shadow direction and length in a picture with SunCalc's figures helps check whether an image fits its claimed place and time. A reverse calculation feature works from sun azimuth and altitude, and an extra panel shows solar data for photovoltaic planning.
Main Features
- Map showing the sun's path for a chosen date and its yearly range
- Time slider and live mode to follow the sun through the day
- Dawn, sunrise, culmination, sunset, dusk and daylight duration
- Sun altitude, azimuth and distance from the earth
- Shadow length calculation for an object height you enter
- Reverse calculation from sun azimuth and altitude
- Equinox and solstice dates plus photovoltaic data such as air mass and irradiance
- Print options and instructions for linking to a set location and time
How to Get Started with SunCalc
- Open suncalc.org and pick your location on the map.
- Set the date, then drag the sun on the time slider to the time you want.
- Read the sun's altitude, azimuth and the shadow direction drawn on the map, and enter an object height to get its shadow length.
- Compare these with the shadows in your photo or scene, and share the exact view using the site's link instructions.
SunCalc Pricing
SunCalc is free. The site asks for an optional donation through PayPal, in an amount you choose, to help keep it online.
Who Should Use It?
- Fact-checkers and OSINT researchers checking whether shadows fit a claimed time and place
- Photographers planning shoots around sunrise, sunset or the light angle
- Architects, home buyers and gardeners studying sunlight on a site
- People planning solar panels who want sun position and irradiance data
- Teachers and students learning how the sun moves across the sky
SunCalc Alternatives
- Bellingcat Toolkit: a free catalogue of open source research tools, with a Geolocation section that includes sun tools.
- Forensically: free in-browser photo forensics tools, including metadata and geotag viewers.
- InVID-WeVerify Plugin: a free verification extension for checking images and videos.
Frequently Asked Questions
Is SunCalc free?
Yes. SunCalc is free to use with no account. You can make an optional PayPal donation to support the site.
How is SunCalc used in fact-checking?
Researchers set the claimed location and date in SunCalc and compare the sun's direction, altitude and shadow lengths with the shadows in a photo or video. A mismatch suggests the image was taken at a different time or place, while a match supports the claim but does not prove it on its own.
Does SunCalc show the moon as well?
The same kind of tool for the moon is on the sister site mooncalc.org, with planetscalc.org for planets and orbtrack.org for satellites.