A free COGO calculator for surveyors

Measure

• Inverse. ΔN, ΔE, ΔZ, azimuth, horizontal distance, slope distance and grade between any two points.
• Angle at a point between any two others.
• Area and perimeter by tapping points or typing numbers. Where a boundary follows an arc, the area uses the true circular segment, not the chord.

Compute new points

• Bearing and distance (radiation) from a known point.
• Intersections: bearing–bearing, distance–distance, four-point line–line, arc–line and arc–arc, plus a two-tap intersection right on the plot.
• Point to line (perpendicular offset), offset to line, midpoint, and station and offset along a baseline or polyline.
• Prorate on line. Proportionate measurement to set a lost corner between two found ones.
• Average points from repeated observations.

Curves and linework

• Arcs by center and radius or through three points, either drawn or with points generated at an interval.
• Spirals. Build a clothoid transition from L, R and the tangent, or fit one to measured field points with RMS and maximum residuals reported.
• Polylines that follow existing arcs, with offsets and stationing.

Adjust and transform

• Traverse closure with precision ratio and a compass rule (Bowditch) adjustment. See how that works.
• Resection from two points (azimuth and distance, or distance only) or three points (Tienstra).
• Rotate, translate and scale the job, and shift all elevations.
• Cut and fill against a flat design elevation or a three-point design plane.

Every change can be undone, and anything that rewrites stored coordinates says so first.

Questions

More from ChainLink Survey

• Traverse adjustmentClosure, precision ratio and compass rule
• StakeoutPoints, lines, curves and cut/fill
• Data collectorUse your phone as a data collector for any total station
• Everything it doesThe full overview