Shadow Length Calculator

Step-by-Step Guide

1. 1Enter the object height: Type the height of the object casting the shadow into the height field. You can enter values in meters or feet — select your preferred unit using the unit toggle. The calculator accepts any positive number, including decimals like 2.5 or 12.75.
2. 2Set the sun elevation angle: Use the angle slider or type directly into the angle field to set the sun's elevation above the horizon in degrees. Values range from 1° (sun near the horizon, very long shadows) to 89° (sun nearly overhead, very short shadows). At 45°, the shadow equals the object height.
3. 3Read the shadow length: The shadow length result appears instantly as you adjust either input. The result is displayed in the same unit as your height input. The visual diagram updates in real time to show the geometric relationship between the object, the sun angle, and the shadow.
4. 4Try different angles for time-of-day analysis: Change the sun angle to model different times of day. Use low angles (10–20°) for morning and evening, mid angles (40–60°) for mid-morning and mid-afternoon, and high angles (70–80°) for midday in summer. This lets you see the full range of shadow lengths your object will cast.
5. 5Use the reference table for quick lookup: Check the shadow length reference table below for pre-calculated values across common sun angles. This is useful for quick checks without entering a specific value — for example, confirming that a 10-meter object casts a 17.3-meter shadow at 30°.
6. 6Export your result: Click the copy button to copy the result to clipboard, or export the diagram as an image for use in design presentations, planning documents, or client reports.

What This Calculator Provides

• ✓Shadow length from any object height and sun angle
• ✓Supports meters and feet
• ✓Real-time result as you adjust inputs
• ✓Visual diagram of the sun–object–shadow geometry
• ✓Shadow length reference table by angle
• ✓Copy result to clipboard
• ✓Export diagram as image
• ✓Works for buildings, trees, poles, people, and any vertical object
• ✓100% browser-based — no data sent to any server
• ✓No signup required

Pro Tips

• 💡For architectural shadow studies, always run calculations for the winter solstice noon angle at your site's latitude — this gives the longest shadows of the year and is the worst-case condition required by most planning authorities. Summer shadows will always be shorter.
• 💡Use the 45° angle as your mental reference point. If you know the sun is above 45° (typical midday in summer at mid-latitudes), the shadow is shorter than the object. If below 45° (mornings, evenings, winter midday), the shadow is longer. This lets you sanity-check any result instantly.
• 💡For solar panel shading calculations, add a 10–15% safety buffer to the calculated shading distance to account for atmospheric refraction, slightly uneven ground, and diffuse light effects near the edge of the shadow zone.
• 💡Shadow direction matters as much as length. This calculator gives you the length, but shadows always point directly away from the sun. In the Northern Hemisphere, midday shadows point north. Morning shadows point west. Combine length with direction for a complete shadow footprint.
• 💡When planning photography shoots, golden hour (sun angle 5–10°) produces shadows 5–11× the object height. Blue hour (angle 0–5°) produces shadows effectively too long to work with compositionally. The sweet spot for long dramatic shadows with still-usable light is 10–20° elevation.

Common Mistakes to Avoid

• ✕Don't use the same sun angle for all seasons. At 51° N, noon sun elevation ranges from about 15° in December to 62° in June — a 47° difference that produces dramatically different shadow lengths. Always use the angle for the specific date and time you are analyzing.
• ✕Don't forget that sun elevation tables give the angle at solar noon (true south), not at a specific clock time. Solar noon can differ from 12:00 by up to 30 minutes depending on your position within your time zone and the equation of time correction.
• ✕Don't assume the formula works for angled or leaning objects. The formula Shadow = Height ÷ tan(Angle) only applies to objects that are perfectly vertical. A slanted wall, pitched roof overhang, or leaning post will cast a shadow with a different length that requires a more complex calculation.
• ✕Don't ignore surrounding buildings when doing site analysis. A shadow study that models only the proposed building in isolation will miss cumulative shading effects from adjacent existing structures, which can compound the shadow impact significantly.
• ✕Don't use 0° or very low angles (under 2°) in calculations — the tangent approaches zero and shadow lengths become theoretically infinite. Sunrise and sunset shadows aren't meaningfully calculable with a simple formula; atmospheric effects and terrain dominate at those angles.

Shadow Length by Sun Angle (10m Object)

Winter Solstice Noon Sun Angle by Latitude

* Winter solstice noon angle = 90° − latitude − 23.5°. Southern hemisphere winter is June solstice.