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Points{{ resultsReady ? computation.values.point_count : '—' }} Mode{{ pathModeLabel }} ModelWGS84
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Point order defines every segment. Closed mode adds the final-to-first edge.
Use decimal degrees in explicit latitude and longitude columns. Up to 50 points stay browser-local.
PointLatitude (°)Longitude (°)OrderRemove
Automatic keeps readable precision and is behavior-neutral.
Measurement
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The chart renderer is unavailable. Exact segment values remain in the ledger.

SegmentFromToDistanceInitial bearingArrival bearingCopy
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Method & limits
Calculation method:
WGS84 inverse geodesics per ordered segment; polygon area from the same ellipsoid.
Ellipsoid
WGS84 · a = 6,378,137 m · 1/f = 298.257223563
Algorithm
GeographicLib geodesic 2.2.0, based on Karney (2013)
Coordinate order
Latitude then longitude, decimal degrees
Canonical units
Metres, square metres, and degrees
Planning estimate, not a survey. Confirm the coordinate datum, source precision, point order, and deliberate closure. The tool does not transform datums, model terrain or routes, diagnose self-intersection, or certify legal boundaries.
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Latitude and longitude describe positions on a reference surface, not distances by themselves. Measuring between them requires a datum and a model of the Earth's shape. WGS84 uses a reference ellipsoid, so a geodesic calculation follows the shortest path on that ellipsoid instead of treating degrees as equal-sized squares on a flat grid.

Point order determines the result. An open path measures each consecutive leg and stops at the last point. A closed polygon adds a final leg back to the first point, then uses the ordered boundary to calculate perimeter and ellipsoidal area. Reordering the same coordinates can create a different route, reverse the winding direction, or form a self-intersection.

ChoiceWhat it answersImportant limit
Open pathTotal geodesic length through two or more ordered points.No area is defined and the last point is not joined to the first.
Closed polygonPerimeter and ellipsoidal area inside three or more ordered boundary points.Self-intersections can produce algebraic area that differs from the shape a reader expects.
Initial bearingThe direction of departure from the start of a segment, clockwise from geodetic north.A geodesic bearing generally changes along a long segment.
Arrival bearingThe forward direction on arrival at the end of the same segment.It is not simply the initial bearing plus 180 degrees.

Coordinate precision sets a practical ceiling on measurement precision. A rounded point copied from a map can move by metres or more, and coordinates from another datum can shift even when the digits look plausible. Displaying more decimal places does not recover missing source accuracy.

Ellipsoidal distance is also not road, walking, sailing, or terrain distance. Obstacles, elevation, legal boundaries, projection rules, and local survey control may all matter more than the shortest WGS84 surface path.

How to Use This Tool:

Confirm that every coordinate is decimal-degree WGS84 data before building the ordered path.

  1. Choose Open path for consecutive travel legs or Closed polygon for a boundary whose last point must return to the first.
  2. Enter latitude from −90 to 90 and longitude from −180 to 180 for each point. Use at least two points for an open path or three for a polygon.
  3. Arrange the rows in traversal or boundary order. Use the move controls when a long or crossing segment reveals that two points are out of sequence.
  4. Choose the distance and area display units. Open Advanced only when two or four fixed decimal places are required; display precision does not change the stored metre and square-metre results.
  5. Compare the total with the segment distances, bearings, closing segment, and winding. Stop if the datum, point precision, or intended closure is uncertain.

Interpreting Results:

For an open path, Path length is the sum of consecutive segment distances. For a closed polygon, Perimeter includes the closing segment and Ellipsoidal area is the magnitude of the signed area generated by the ordered boundary.

  • A surprisingly long segment usually points to row order, a longitude sign, or an unintended closure. Check that segment before trusting the total.
  • Clockwise and Counter-clockwise describe point order. They do not judge whether the boundary is valid.
  • Matching a rough map measurement increases confidence in data entry, but it does not turn the result into a survey or legal boundary certificate.

Technical Details:

Each segment is solved as an inverse geodesic on the WGS84 ellipsoid. The inverse solution returns ellipsoidal distance plus forward bearings at both endpoints. Polygon accumulation uses the same ellipsoid, handles antimeridian crossings, and preserves signed area so winding can be reported before the displayed area takes the absolute value.

Formula Core:

Total length is the sum of the inverse-geodesic segment lengths. Closed mode includes the last-to-first segment, while open mode does not.

D=∑i=1msi A=Asigned θ=αmod360+360mod360

Here, si is one WGS84 inverse-geodesic distance in metres, m is the number of measured segments, Asigned is the accumulated ellipsoidal polygon area in square metres, and α is a returned azimuth. Bearing normalization places the displayed direction from 0 degrees inclusive to 360 degrees exclusive.

Mechanism Core:

StageMethodResult
ValidateAccept 2 to 50 ordered points; require 3 or more for a closed polygon.Finite decimal-degree latitude and longitude within global bounds.
Solve segmentsApply the WGS84 inverse geodesic between each consecutive pair.Distance, initial bearing, and arrival bearing for every segment.
Close when requestedAdd the last-to-first geodesic only in closed mode.Closing distance and complete perimeter.
Accumulate areaUse ellipsoidal polygon accumulation with signed orientation.Signed area, absolute area, and winding.
Convert for displayApply exact fixed conversion factors to canonical metres and square metres.Selected units without changing the calculation.
Display unitCanonical conversion
Kilometresmetres ÷ 1,000
Milesmetres ÷ 1,609.344
Nautical milesmetres ÷ 1,852
Feetmetres ÷ 0.3048
Hectaressquare metres ÷ 10,000
Acressquare metres ÷ 4,046.8564224
Square feetsquare metres ÷ 0.09290304

Limitations:

The calculation assumes every coordinate already belongs to WGS84. It does not transform local datums or projected coordinates, model elevation and terrain, follow roads or waterways, or repair a self-intersecting polygon.

  • Do not use the result to certify cadastral boundaries, construction staking, engineering tolerances, or legal area.
  • Coordinates remain in the browser, but a shareable URL created after interaction can expose them to anyone who receives that URL.
  • Use authoritative GIS or survey control when safety, property rights, or construction depends on the measurement.

Worked Examples:

One-degree square near the equator

Four points at (0°, 0°), (0°, 1°), (1°, 1°), and (1°, 0°), entered in that order and closed, produce a perimeter of about 443,770.917 metres and an ellipsoidal area of about 12,308,778,361 square metres. The east-west and north-south edges are not identical because WGS84 is ellipsoidal, and reversing the row order changes the winding while leaving the absolute area unchanged.

References: