Blog · September 27, 2026
How to Read a Curve on a Plat
A curve on a plat is an arc with a radius, a length, and a direction, used for streets and for lot lines that follow them.
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The table or the line label gives radius, arc length, and delta angle. The chord bearing is the straight shortcut across the arc, not the boundary itself when the boundary is the arc.
On the recorded sheet
Lot frontage on a cul-de-sac is often the arc. Fencing the chord cuts off a sliver.
The mix-up to avoid
If the curve data is missing, you do not invent a radius from the picture. You get a clearer copy of the plat.
Find the county map
Start at Platbookmapper, search the county, and open the local GIS link. Write down the parcel number before you compare the screen to a paper plat.
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey.