COGO Survey Calculator

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

WHAT YOU CAN DO
• Bearing-and-distance traverse with running coordinates; edit any leg in place; enter legs in metres, feet, US survey feet, or links
• Inverse / join: two points to distance, azimuth, and quadrant bearing
• Inverse list / radiations: bearing & distance from one point to every other point
• Sideshot reduction: horizontal angle, zenith, and slope distance to northing, easting, and elevation
• Closure: linear misclosure, misclosure bearing as azimuth or quadrant (your choice), 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 a deflection / chord stakeout table (CSV)
• 3-point circle / arc — fit a circle through three points and divide the arc into stake points
• Angle calculator — add/subtract angles, angle between two bearings, bearing ± angle, editable running total
• POB calculator — chain editable bearing-distance calls from a point of beginning
• COGO intersections — bearing-bearing, bearing-distance, distance-distance — and 3-point (Tienstra) resection
• Line tools — four-point intersection, parallel and perpendicular lines with station, offset, and left/right
• Common tangent — all four tangents between two circles from two centres or a bearing + distance, with offsets
• Two unknowns — solve two missing traverse distances, bearings, or one of each, offsets included
• Recessed invert — reduce a slant tape shot to pipe invert depth and elevation
• UTM converter — latitude/longitude as decimal degrees, DMS with N/S/E/W, DDMMSS, or packed D.MS
• State Plane (SPCS83 and SPCS2022 preview) — lat/lon to grid with scale factor, convergence, and combined factor
• Grid ↔ Ground converter — distances through a typed or zone-derived combined scale factor
• Horizontal alignment — PI-chained tangents, curves, optional spirals, stationing, station & offset, stakeout
• Predetermined / hinged area subdivision — parallel cutoff or hinged line to a target 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/export points as CSV in your column layout (PNEZD, PENZD, NEZ, ENZ …) and delimiter
• Export DXF (AutoCAD R12) and a one-page PDF report — CSV, DXF, and PDF export are free
• Work in DMS, decimal, or packed D.MS; azimuth or quadrant; feet or metres — set your defaults once
• Native iOS keyboard by default, or the in-app survey keypad with 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