Crown Spread

Stand under the widest point of the canopy on one axis, walk out to the drip line (the outer edge of the foliage) in each direction, and measure the total distance — that's your north-south or east-west reading. Do it on both axes. A tape and a compass work; on an open site a laser rangefinder is faster and more consistent, especially on a tree with an irregular or leaning crown where "straight down from the drip line" isn't obvious without one.

Average the two spread readings to get a crown diameter, then treat the crown as a circle of that diameter to estimate canopy area (π × radius²). It's an approximation — real crowns are lopsided, asymmetric, and rarely a clean circle — but it's the standard shorthand used across inventories and canopy-cover studies, and it's consistent enough to compare trees against each other or track a single tree's growth over time.

Crown spread feeds urban canopy-cover targets (a municipality tracking percentage tree cover across its jurisdiction), informs shading and stormwater interception estimates, and matters directly for site layout — a wide-crowned tree constrains where a building, driveway, or utility trench can reasonably go, independent of what its root protection area (a separate, root-based calculation) requires.

It also shows up in appraisal work: several tree valuation methods weight a tree's worth partly by canopy size, on the reasoning that a bigger, healthier crown is doing more environmental and aesthetic work than a stunted one of the same species and age. Two trees with identical DBH can have very different appraised values if one has a full, wide crown and the other has been crowded or topped.

Trees growing near a building, fence line, or other tree often develop a lopsided crown — reaching further toward open light on one side and staying compact on the other. Recording both N-S and E-W readings (rather than a single "crown width" guess) captures that asymmetry, which matters if the survey is being used to judge clearance from a structure or a neighboring property line, not just to estimate overall canopy area.

See the tree inventory guide for where crown spread fits alongside DBH and condition, or LogLog's crown spread fields — enter the N-S and E-W readings and the app derives crown diameter and canopy area automatically, so it's not a spreadsheet formula you're maintaining separately.