Estimate tree height from angles and distance or paired shadows.
Estimate height from an angle or matching shadows. Your results can be printed or downloaded for field use.
Enter your measurements, then calculate.
Method and assumptions
Angle method: height = horizontal distance × tan(top angle) + eye height. Assume level ground and an upright tree with its top over its base; do not substitute sloping tape distance. Shadow method: height = tree shadow × reference height ÷ reference shadow. Measure both shadows at the same time on level ground with a vertical reference. Leaning trees, uneven ground and unclear tops cause errors. NPS clinometer field lesson.
Instructions
- Choose Measurement method and Length unit.
- For Angle and eye height, enter Horizontal distance to trunk, Angle to top (degrees above horizontal) and Eye height above tree-base level.
- For Matching shadows, measure Tree shadow length, Reference object height and Reference object shadow length at the same time.
- Select Calculate and keep the result with Print result or Download CSV.
Understanding your results
On level ground, a tree 20 m away with a 45° top angle and 1.6 m eye height gives an estimate of 21.6 m. The shadow method compares proportions. Both methods depend on an upright tree, clear measurements and suitable ground.
What to do if the height changes a lot between attempts
Check you have sighted the actual top and measured horizontal distance, not the length along a slope. For shadows, use a vertical reference and measure both shadows together. Try several positions and compare estimates.
Using this tool in your browser
This tool handles your entries in your browser with JavaScript enabled and does not save them automatically. Use the download or print controls described in the instructions to keep a copy before closing or reloading the page. On a phone, your browser controls where downloads go and which print options are available.
Summary
Record your measurement method and repeat the estimate before relying on a single reading.