Marine & Navigation

Great Circle vs Rhumb Line Calculator

Compare great-circle and rhumb-line distance, bearing, and ETA.

Last validated: 2026-02-14

Great Circle vs Rhumb Line Calculator compares shortest-path great-circle routing with constant-bearing rhumb-line routing between two coordinates. It is useful for passage planning, voyage briefings, and assessing tradeoffs between distance efficiency and steering simplicity. The tool reports distance, initial bearing, and ETA for both methods at a selected speed. Use it to frame route strategy, then validate with weather routing and operational constraints.

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Input Pattern

Enter values in the left panel, keep units explicit, run the calculation, then copy or share the result. Invalid fields are highlighted immediately.

Route Inputs

Result

Great-circle distance: 4467.935 nm

Great-circle initial bearing: 303.36°

GC ETA: 319.14 h

Rhumb-line distance: 4713.825 nm

Rhumb bearing: 268.47°

Rhumb ETA: 336.70 h

How to use this tool

Enter departure and destination latitude/longitude coordinates.
Set expected vessel speed and run the route comparison.
Compare great-circle and rhumb-line distance, bearing, and ETA to choose planning baseline.

Worked Example

Auto-generated from the tool's current default or entered inputs.

Example Inputs

Lat1 deg: 37.7749
Lon1 deg: -122.4194
Lat2 deg: 35.6762
Lon2 deg: 139.6503
Speed kn: 14.0
Great circle distance nm: 4467.934920046277
Great circle initial bearing deg: 303.35645413824943
Rhumb line distance nm: 4713.824890149167

Expected Outputs

Lat1 deg: 37.7749
Lon1 deg: -122.4194
Lat2 deg: 35.6762
Lon2 deg: 139.6503

Interpretation

Lat1 deg is 37.7749. Use this as a decision input, not as a standalone conclusion.
Lon1 deg is -122.4194. Use this as a decision input, not as a standalone conclusion.
Lat2 deg is 35.6762. Use this as a decision input, not as a standalone conclusion.
Cross-check the result against one alternate input set to validate sensitivity.

Scenario Compare (A vs B)

Use this to compare two input sets and quantify change in key outputs.

Scenario A

Lat1 deg

Lon1 deg

Lat2 deg

Lon2 deg

Speed kn

Great circle distance nm

Great circle initial bearing deg

Rhumb line distance nm

Scenario B

Lat1 deg

Lon1 deg

Lat2 deg

Lon2 deg

Speed kn

Great circle distance nm

Great circle initial bearing deg

Rhumb line distance nm

Explore more versions

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Great Circle vs Rhumb Line Calculator

Input Pattern

Route Inputs

Result

How to use this tool

Worked Example

Example Inputs

Expected Outputs

Interpretation

Scenario Compare (A vs B)

Scenario A

Scenario B

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