Find out how tall your tree is in about a minute — sunlight, a mirror, or your phone, whichever you've got on hand.
Pick the method that fits your day — sunny, cloudy, or somewhere in between — enter a few measurements, and get an instant height estimate with the math shown plainly on the side.
Get your tree's height in just a few simple steps.
Choose the option that fits today's light and what you have on hand — sun, a mirror, or your phone.
Follow the short steps for that method — shadows, mirror distances, or a couple of phone angles.
Type your measurements into the calculator. It updates the result as you go.
See the estimated height instantly, with the full math laid out beside it.
All three methods lean on the same idea foresters and arborists have used for generations — similar triangles and simple trigonometry — just measured in different ways.
Compare the tree's shadow to the shadow of something you already know the height of. The two shadows scale the same way, so the ratio between them tells you the tree's height.
A mirror on the ground reflects the treetop back to your eye. The triangle formed by your eye and the mirror is a smaller copy of the triangle formed by the tree and the mirror.
Your phone reads the angle up to the tree top and down to the base. Multiplying your distance from the tree by those angles gives the height directly.
What each method runs behind the scenes when you press "Calculate Tree Height."
Tree Height = (Tree Shadow ÷ Object Shadow) × Object Height
Example: (48 ft ÷ 4 ft) × 5.5 ft = 66 ft
Tree Height = (Tree-to-Mirror Distance ÷ You-to-Mirror Distance) × Eye Height
Example: (60 ft ÷ 10 ft) × 5.5 ft = 33 ft
Tree Height = Distance × (tan(Angle to Top) − tan(Angle to Base))
Example: 60 ft × (tan(32°) − tan(−4°)) = 42 ft
Important: These formulas estimate height from measurements you take yourself, not a laser or licensed survey instrument. For a certified figure — say, for insurance or legal purposes — have a professional arborist measure the tree with calibrated equipment.
A quick side-by-side so you can pick the right method before you walk outside.
| Method | Sunlight Needed | Tools Needed | Difficulty | Best For |
|---|---|---|---|---|
| ☀️ Shadow Method | Yes | Tape measure | Easy | Quick outdoor estimate on a sunny day |
| 🪞 Mirror Method | No | Small mirror + tape measure | Easy | Cloudy days, shaded yards |
| 📱 Phone Angle Method | No | Smartphone | Advanced | Most flexible — works in almost any light |
Quick answers to common questions about measuring a tree's height.
On a sunny day, the Shadow Method is simplest — just compare the tree's shadow to the shadow of something you already know the height of, like yourself.
No. The Shadow Method needs sunlight, but the Mirror Method and Phone Angle Method both work on cloudy days or in shade.
Lay a small mirror flat on the ground between yourself and the tree, then step back until you see the treetop reflected in it. Your distances and eye height scale up to the tree's real height.
It's a solid estimate, not a certified measurement. It uses your phone's motion sensor to read two angles, and readings can vary slightly between phones, so it's worth double-checking your first result.
You can, but flat ground gives a more accurate result with all three methods. A slope between you and the tree throws off the shadow ratio, the mirror reflection, and the angle math.
The Phone Angle Method has a fallback for this — turn on "use my eye height instead" in the advanced options and it will estimate height from the top angle and your eye height alone.
No. A tape measure covers the Shadow and Mirror methods, plus a small mirror for the Mirror Method. The Phone Angle Method just needs a smartphone.
Arborists use this same math with calibrated tools like a clinometer, so these methods land close when done carefully on flat ground. Treat the result as a strong ballpark rather than a survey-grade figure.