COGO Survey Calculator

v2.0 adds bearing angle tools, POB chaining, DMS/DDMMSS UTM input, packed D.MS defaults, native keyboard preference, and new Pro pricing.

Native COGO calculator for surveyors and field crews — traverse, closure, curves, intersections, area, and CAD export. Fully offline.

WHAT YOU CAN DO • Compute a bearing-and-distance traverse with running coordinates • Inverse / join: two points to distance, azimuth, and quadrant bearing • Inverse list / radiations: bearing & distance from one occupied point to every other point at once • Sideshot reduction: horizontal angle, zenith angle, and slope distance from an occupied station to northing, easting, and elevation • Closure: linear misclosure, misclosure bearing, and precision ratio (1 : N) • Balance a traverse by the Compass (Bowditch) or Transit rule • Enclosed area by coordinates, with acres / hectares and perimeter • Horizontal curve solver — R, Δ, arc, tangent, chord, external, mid-ordinate, degree of curve, PC & PT — plus deflection-angle / chord stakeout, exportable as CSV • 3-point circle / arc — fit a circle through three points and divide the arc into equally spaced stake points • Angle calculator — add/subtract angles, compute the angle between two bearings, add/subtract an angle from a bearing, and keep an editable running total • POB calculator — chain editable bearing-distance calls from a point of beginning and read every running coordinate • COGO intersections — bearing-bearing, bearing-distance, distance-distance — and 3-point (Tienstra) resection • UTM converter — enter latitude/longitude as decimal degrees, DMS with N/S/E/W, compact DDMMSS, or packed D.MS • State Plane Coordinates (SPCS83) — lat/lon to State Plane on GRS80/NAD83, with scale factor, convergence, and combined grid-to-ground factor • Grid ↔ Ground converter — convert distances through a combined scale factor, typed directly or derived from a State Plane zone and position • Horizontal alignment / roading — PI-chained tangents, circular curves, optional spirals, stationing, station & offset, and stakeout • Predetermined / hinged area subdivision — solve a missing bearing/distance, a parallel cutoff, or a hinged line to hit a target parcel area • Metes-and-bounds legal description — generate a written deed description from a closed traverse • Plot / sketch view of the traverse with north arrow, scale bar, and legend • Import and export points as CSV in your choice of column layout (PNEZD, PENZD, NEZ, ENZ …) and delimiter • Export DXF (AutoCAD R12) for CAD / GIS and a single-page PDF report — CSV, DXF, and PDF export are free for everyone • Work in DMS, decimal degrees, or packed DDD.MMSS / D.MS (CAD and Topcon-style); azimuth or quadrant bearing; feet or meters • Use the native iOS number keyboard by default, or switch to the in-app survey keypad when you want dedicated DMS keys • Ask “Theo,” the on-device AI assistant (Apple Intelligence), in plain English

PRIVATE BY DESIGN 100% offline. No account, no network, no ads, no tracking. Your jobs and points never leave your device.

WHO IT'S FOR Land surveyors, party chiefs, survey techs, civil engineers, and students.

FREE & PRO Free includes one job and up to ten points, full on-screen computation, and CSV / DXF / PDF export. COGO Pro unlocks unlimited jobs and points, Compass/Transit closure adjustment, and enclosed-area output — as a Weekly, Monthly, or Yearly subscription, or a one-time Lifetime purchase.

Always verify computed results against your project control. This app is a field calculator, not a substitute for a licensed surveyor's checks.

SUBSCRIPTION DETAILS COGO Pro Weekly, Monthly, and Yearly are auto-renewable subscriptions; Lifetime is a one-time purchase. Payment is charged to your Apple Account at confirmation. Subscriptions renew automatically unless cancelled at least 24 hours before the end of the current period; manage or cancel anytime in Settings. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://cogo.vendrato.com/privacy