Sun Shadow Length and Direction Calculator

Estimate a vertical object's shadow length along level ground and its bearing from the object's base toward the shadow tip.

1. Enter latitude and longitude in decimal degrees. Latitude is positive north and negative south; longitude is positive east and negative west.
2. Enter the date and time with seconds and an explicit UTC offset, such as 2026-06-21T12:00:00+00:00. Here, T separates the date from the time, and +00:00 is the UTC offset, meaning the time is in UTC. Use the correct offset for your location and date, including daylight saving where applicable.
3. Enter the vertical object's height in metres, from 0.01 to 1000.

The defaults are a fixed example at 51.5° north, 0° longitude, on 21 June 2026 at 12:00:00 UTC, with a 2 m object. They do not detect your location or the current time.

The calculator first estimates the Sun's altitude and azimuth for the entered location and instant. Altitude is the Sun's angle above the horizon. Azimuth is its compass direction, measured clockwise from true north.

Shadow length equals object height divided by the tangent of solar altitude. Shadow bearing is the solar azimuth plus 180°, wrapped into the range 0° to less than 360°. Shadow length is measured along the ground from the object's base toward the shadow tip in the reported bearing.

Bearings are measured clockwise from true north: 0° is north, 90° east, 180° south and 270° west. A magnetic compass may require a local declination correction.

In a hypothetical geometry example, a 2 m vertical object with the Sun at 45° altitude casts a 2 m shadow on level ground. If the Sun's azimuth is 180°, that shadow points north. These angles are hypothetical, not the calculated result for the preset location and timestamp; the preset 2 m object should not be expected to produce this example's 2 m shadow.

Each result describes one entered instant. To compare shadows at different times for approximate planning, change the existing date-and-time input while keeping the location and object height fixed. This lets you compare individual shadow lengths and bearings; the calculator does not model a full building, an area of shade or an all-day simulation.

This is an idealized estimate for a vertical object on horizontal ground with an unobstructed view of the Sun. Sloping ground, leaning objects, nearby obstacles and atmospheric conditions can change the observed shadow. The calculation does not predict cloud cover or whether direct sunlight reaches the object.

• Sun at or below the horizon: At or below the calculated horizon, shadow length and bearing are unavailable, not zero.
• Extremely long shadows: Very low positive solar altitudes produce long shadows that are especially sensitive to small input and solar-position errors. Finite lengths above 100,000 m display as Extremely long. If a finite numerical length cannot be produced, the shadow length is unavailable.
• Sun directly overhead: The ideal shadow length is zero and its direction has no practical meaning.

Displayed decimal places describe rounding, not guaranteed accuracy. No numerical accuracy guarantee is supplied for the solar-position model. Use these results for approximate planning rather than precision surveying.

For a separate view of the Sun's position, use the Sun Altitude and Azimuth Calculator.