Use this sailing calculation as a planning or educational cross-check for navigation, wind and current, rig loads, stability, anchoring, tides, visibility, performance, or recovery under explicitly stated conditions.

From latitude

Required number input.

From longitude

Required number input.

To latitude

Required number input.

To longitude

Required number input.

Calculate the great circle distance in nautical miles between two geographic positions. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Distance

The resulting distance returned as a number.

• Actual conditions change with vessel design and loading, sea state, wind, current, tide datum, weather, chart accuracy, equipment, crew, regulations, and safety margins. Simplified formulas do not replace seamanship, approved stability data, or current navigation information.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Cross-check official charts, tide and weather services, instrument data, vessel manuals, and collision regulations; maintain conservative margins and a safe alternative plan.

• Distance to Layline Calculator

  Calculate the distance along the course centerline to a layline from the lateral offset and half of the total angle between port and starboard tacks.

• Horizon Distance Calculator

  Compute the distance to the visible horizon in nautical miles as the coefficient one point one seven times the square root of eye height in feet.

• Horizon Range Calculator

  Compute the distance to the visible horizon in nautical miles as one point one seven times the square root of the observer height in feet.