Time & Sun
World Sun Direction & Shadow Length Calculator
Find the sun's current altitude and bearing, and the length and direction of the shadow cast by any object — for architecture, photography and solar planning.
Sun & shadow — London
Sun is below horizon
No shadow while the sun is down. Try a different city or wait for sunrise.
Computed live from the NOAA solar position model. Shadow length = object height ÷ tan(sun altitude); direction is opposite the sun's azimuth.
Why sun direction and shadow matter
Where the sun sits in the sky — and the shadow it casts — drives architecture, photography, solar energy, gardening and even how warm a room feels. A building designed without sun-direction analysis bakes in summer and freezes in winter; a photograph taken at the wrong hour misses its light; a solar panel angled wrong loses output. Knowing the sun's altitude and azimuth, and the resulting shadow, is the foundation of designing with daylight.
This calculator gives the live sun position for any city and the shadow an object of any height would cast right now, updating every second from the NOAA solar model.
Altitude and azimuth: the two angles
The sun's position is described by two angles. Altitude is how high the sun is above the horizon (0° at sunrise and sunset, up to 90° if it is directly overhead at the tropics). Azimuth is the compass direction of the sun — where to look to face it. Together they fully specify where the sun is at any instant.
Altitude drives shadow length (low sun, long shadow); azimuth drives shadow direction. As the day progresses, the sun rises in altitude then falls, and its azimuth sweeps from east to west, so a shadow both shortens then lengthens and rotates clockwise (in the northern hemisphere) through the day.
How shadow length is computed
Shadow length follows directly from the sun's altitude: shadow = object height ÷ tan(altitude). A 2-metre post with the sun at 30° casts a 3.5-metre shadow; at 60° it casts 1.2 metres; at the horizon it stretches to infinity. The tool computes this live for the height you enter and the current sun altitude at the selected city.
When the sun is below the horizon (night, or before sunrise / after sunset), there is no shadow and the tool says so. Around sunrise and sunset, the shadow is very long and softens as the sun drops below the horizon — the moment photographers call golden and blue hour.
Shadow direction: opposite the sun
A shadow always points away from its light source. If the sun bears south, the shadow bears north; if the sun is in the east, the shadow points west. The tool reports both the sun's compass bearing and the shadow's, so you can lay out a scene or a structure knowing exactly which way a shadow will fall.
In the northern hemisphere, the sun spends midday in the south, so north-facing walls are in shade and south-facing ones catch the sun; the reverse holds in the southern hemisphere. This is why orientation matters so much in building design — getting it right is free heating and lighting forever.
Using the tool for architecture and solar
Architects use sun direction to design shading — overhangs that block high summer sun but admit low winter sun, and to place windows for warmth or cool. Solar installers use altitude and azimuth to set panel tilt and azimuth for maximum yield and to predict shading from nearby objects across the year. This live calculator gives the current numbers; for full-year analysis, a solar path diagram extends the same angles across all days.
For a quick check — 'will this tree shade my panels at midday in winter?' — set the city, note the sun's midday altitude (lowest around the December solstice in the north), and see whether the resulting shadow reaches the panel. The same logic sizes the shade structure that would block it.
Photography and the direction of light
Photographers think in light direction as much as light quality. Front light (sun behind the camera) flatters and flattens; side light reveals texture and form; back light rims and silhouettes. Knowing the sun's azimuth at a location tells you which angle you will be shooting from at a given hour, so you can plan when to arrive for the light you want.
Pair this tool with the Sun & Golden Hour Calculator: the latter tells you when the light is soft and warm, and this one tells you which direction it comes from. Together they let you plan a shoot to the minute, knowing exactly where to stand and when the magic happens.
Frequently Asked Questions
How is shadow length calculated?
Shadow length equals the object's height divided by the tangent of the sun's altitude angle. A low sun casts a long shadow; a high sun casts a short one. When the sun is below the horizon, there is no shadow.
What do altitude and azimuth mean?
Altitude is the sun's angle above the horizon (0° at horizon, 90° overhead). Azimuth is the compass direction of the sun. Together they fully describe where the sun is in the sky at any moment.
Why is the shadow direction opposite the sun?
Shadows always point away from the light source. If the sun is in the south, the shadow points north; if the sun is in the east, the shadow points west. The tool reports both the sun's bearing and the shadow's.
How accurate is the sun position?
It uses the NOAA solar position algorithm, accurate to a small fraction of a degree for any location and time. Tiny differences from observed shadow lengths come from local horizon obstructions and atmospheric refraction near sunset.
What is this useful for?
Architects use it to model shading; photographers use it to plan light direction; solar installers use it to size arrays and predict output; gardeners use it to plan sun and shade beds. Anywhere sun position matters, this tool gives the live numbers.
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