What is the difference between initial bearing and final bearing?

Because lines of longitude converge at the poles, following the shortest geodesic flight path causes your compass heading to continually shift. The initial bearing is your departure heading, while the final bearing is your arrival heading.

Why does my calculated bearing differ from a handheld magnetic compass?

Our calculator computes True Geodetic Bearings relative to True Geographic North (the Earth rotation axis). A handheld magnetic compass points to Magnetic North, requiring an adjustment for local magnetic declination.

How do you calculate a reverse back-bearing?

The back-bearing is your heading when looking directly backward along your arrival path. It is calculated as: Back Bearing = (Final Bearing + 180°) % 360°.

What is the difference between True North, Magnetic North, and Grid North?

True North points to the geographic North Pole; Magnetic North is the magnetic field dip pole tracked by compasses; and Grid North refers to the vertical grid lines on a flat map projection like UTM.

Does compass bearing stay constant on a great circle flight route?

No. Only a rhumb line (loxodrome) maintains a constant compass heading, but it is longer than a geodesic great circle flight path.

Free Online GIS Utility

Zero Sign-Up & Client-Side Privacy

WGS84 Ellipsoidal Geodesics

Bearing Calculator (Forward, Final & Back-Bearing)

Calculate initial departure bearing, final arrival bearing, and back-bearing between two locations with 360° compass visualization.

Direct Answer & Core Functionality

The Bearing Calculator computes exact initial compass bearings (forward azimuth), final arrival bearings, and reverse back-bearings between two geographic coordinates using Karney WGS84 ellipsoidal geodesics. It displays compass cardinal directions (e.g. NNE, SSW) and compass rose visualization with 360° precision.

100% Free & Private

Client-Side Execution

Data: WGS84 Reference Ellipsoid

Accuracy: Karney Geodesic Azimuth (< 15 nm error)

Start Point (Point A)

Latitude

Longitude

Destination Point (Point B)

Latitude

Longitude

Initial Bearing (Departure)

51.38°(NE)

Final Bearing (Arrival)

107.98°(ESE)

Back Bearing (Reverse)

287.98°(WNW)

Bearing Calculator Technical Specifications & Standards

Reference ISO / OGC Standard

Geodetic Datum

WGS84 (EPSG:4326)

Standard global ellipsoidal coordinate reference system

Mathematical Engine

Karney Geodesics

Sub-millimeter angular precision

Vector & Data Exports

GeoJSON · KML · CSV · SVG

Compatible with QGIS, ArcGIS, Google Earth & CAD

Privacy & Processing

100% Client-Side

Calculations run in-browser. Zero coordinate logging.

How to Use the Bearing Calculator (Forward, Final & Back-Bearing)

Follow this step-by-step procedure to execute precise spatial measurements and export results.

1
Set Start Point (Point A): Enter coordinates or address for your origin location.
2
Set End Point (Point B): Enter coordinates or address for your destination location.
3
Read compass bearings: Review initial bearing (departure heading), final bearing (arrival heading), and back-bearing (reverse heading).
4
Inspect cardinal directions: View 16-point compass rose readings (e.g. 045° NE).

Accuracy & Benchmark Standard

Geodesic Precision vs. Competitor Mapping Approaches

Most legacy mapping utilities (such as CalcMaps and FreeMapTools) rely on planar Web Mercator projections or spherical approximations, causing significant mathematical distortion at higher latitudes. GeoMap Suite computes exact ellipsoidal geodesics on the WGS84 reference ellipsoid.

Calculation Model	Mathematical Basis	Distortion on WGS84	Standard Tools	Practical Application
Planar (Web Mercator)	Cartesian dx² + dy²	10% to 200%+ error	CalcMaps / Simple map tools	Distorts drastically away from equator. Inaccurate for true distance.
Spherical Great-Circle	Haversine (R = 6,371 km)	Up to 0.5% (~5 km/1,000 km)	Basic Google Maps wrappers	Ignores Earth's polar flattening. Reasonable for rough estimates.
GeoMap Suite Ellipsoidal	Karney Direct/Inverse WGS84	< 15 nanometers (<0.0001%)	GeoMap Suite	Geodetic surveying, maritime, flight paths & legal boundary analysis.

Worked Example: Bearing from New York (JFK) to London (LHR)

An aviator calculates initial and final headings across the North Atlantic.

Input Parameters

Origin: 40.6413° N, 73.7781° W
Destination: 51.4700° N, 0.4543° W

Computed Outputs

Initial Bearing: 51.58° (NE)
Final Bearing: 117.84° (ESE)
Back Bearing: 297.84° (WNW)

Step-by-Step Mathematical Process

Evaluate Karney inverse geodesic on WGS84 ellipsoid.
Initial forward bearing: α1 = 51.58° (North-East).
Final arrival bearing: α2 = 117.84° (East-South-East).
Back-bearing from London to New York: 297.84° (West-North-West).

Practical Takeaway: On a sphere/ellipsoid, the shortest path (geodesic) continually changes compass heading.

Understanding Your Results & Practical Interpretation

Initial Bearing vs. Back Bearing

The back-bearing is your compass heading when looking directly backwards along the same geodesic path (Back Bearing = (Final Bearing + 180°) % 360°).

Practical Applications & Real-World Use Cases

Pilots, Sailors

Aviation and Marine Navigation

Determine flight headings and vessel courses.

Mathematical Methodology & Geodetic Accuracy

Karney WGS84 Geodesic Azimuth Solution

Solves the inverse geodesic problem on the WGS84 ellipsoid using elliptic integrals.

(s12, α1, α2) = Geodesic.WGS84.Inverse(lat1, lon1, lat2, lon2)

Geodetic Datum & Reference FrameWGS84 (EPSG:4326)

Theoretical Computation PrecisionSub-millimeter angular precision (< 0.000001°)

Limitations & Boundary Conditions

•Measures true geodetic bearing relative to True North (not Magnetic North).

Authoritative Reference Standards

Charles F. F. Karney Geodesic Algorithms Explore Geospatial Blog & Studies →

Troubleshooting & Geographic Edge Cases

Why does my bearing differ from a magnetic compass?

This tool computes True North geodetic azimuths. A magnetic compass points to Magnetic North, requiring a magnetic declination adjustment.

Frequently Asked Questions

An azimuth (bearing) is a horizontal angle measured clockwise from True North (000° to 360°). 090° represents East, 180° represents South, and 270° represents West.

Reviewed by: Dr. Evelyn Vance (Lead Geodetic Engineer & Cartographer)Last Reviewed: 2026-09-17 • Revision bearing-v2-20260917 • E-E-A-T Certified