Updated September 2026
If you've plotted a boundary with this tool and seen a "closure error" number or a warning banner, this page explains exactly what that means, where the number comes from, and what to actually do about it.
A metes and bounds description walks a parcel's boundary as a sequence of straight calls, starting from a point of beginning (POB). If every bearing and distance is correct, walking all of them in order — literally adding up each call's direction and length — brings you back to the exact POB after the last call, because the boundary is, by definition, a closed shape. Closure is the property of the calls actually doing that; a description that closes is internally consistent.
In practice, the sum of all the calls almost never lands on precisely (0, 0) relative to the POB, for two independent reasons. First, real field surveys have measurement uncertainty — a chain or tape has a small stretch, an angle read off a transit or total station has a small instrument error, and these accumulate call by call across a traverse. Second, and often larger in an old or hand-transcribed deed, is transcription error — a bearing or distance copied slightly wrong from an original survey plat into the deed document, or copied wrong again when the deed was re-typed or OCR'd decades later. This tool cannot tell these two sources apart; it only reports the combined result.
The tool sums every call's (dx, dy) displacement (see the math page for the full bearing-to-vector conversion) and reports the straight-line distance from that final point back to the POB — the raw closure error, in feet. On its own, a 2-foot error is meaningless without context: on a 300-foot-perimeter suburban lot it's a serious flag, but on a 30,000-foot rural boundary it's essentially perfect. So the tool also computes a precision ratio: perimeter divided by closure error, shown as "1:N" — e.g., "1:12,500" means the traverse closed to within 1 part in 12,500 of its total length.
There's no single universal legal threshold, but the professional surveying community has long-standing conventional bands. Historically, urban and suburban boundary surveys were commonly expected to close better than 1:10,000, with many jurisdictions and firms targeting 1:15,000–1:20,000+ for higher-precision urban work using modern total-station or GPS equipment. Rural, mountainous, or heavily wooded rural tracts — where sight lines are harder and older equipment may have been used originally — are more often accepted in the 1:5,000–1:7,500 range or occasionally looser for very old descriptions. This tool uses roughly those same bands to color its closure banner: green ("closes cleanly") above about 1:5,000, amber ("looser than typical") between roughly 1:1,000 and 1:5,000, and red ("likely a transcription mistake") below 1:1,000.
A very poor closure ratio — say 1:200 or worse — on a description you're transcribing from a deed almost always points to a data entry error on your part or a transcription error already present in the deed text, not a genuinely bad original survey. The most common causes, in roughly descending order of frequency: a flipped quadrant letter (N written where S belongs, or vice versa — this doesn't just shift one call, it mirrors every call after it), a transposed digit in a distance, a misread minutes or seconds value in dense old text, and occasionally an entire call skipped or duplicated. A closure error that's exactly one call's length, or very close to twice one call's distance, is a strong hint that one specific call is wrong or duplicated — check that one first.
Work backward through the calls, checking each one against the original deed text — errors near the end of the sequence are the easiest to introduce and the easiest to miss, since they only affect the last leg or two. If every call matches the deed exactly and the closure is still poor, the description itself may simply be an old survey with genuine field measurement error carried forward for decades in the public record — which happens more often than you'd expect with descriptions written before modern equipment, and is itself useful information for a title researcher or landowner to know before relying on the description.
A perfect closure (ratio effectively infinite) confirms the calls are numerically self-consistent — it does not confirm the description matches reality on the ground, that the POB is correctly located, or that no call was altered in a way that happens to still close (e.g., two compensating errors that cancel out). Closure is a necessary sanity check, not a guarantee of accuracy — which is exactly why an actual boundary dispute or title question still needs a licensed surveyor's field work, not just a clean plot from this tool.