Difference Between GDA94 and GDA2020

Analyze the 1.8-meter tectonic shift between Australia's GDA94 and GDA2020 datums. Explore the legal, agricultural, and surveying impacts of this coordinate change.

GDA2020 (EPSG:7844)
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Magnitude: 1.8 meters
GDA94 (EPSG:4283)

1. The 1.8 Meter Australian Plate Shift

The Australian tectonic plate is one of the fastest moving on Earth, shifting north-east at approximately 7 centimeters per year. By the year 2020, coordinates based on the legacy Geocentric Datum of Australia 1994 (GDA94) had drifted 1.8 meters from their absolute global positions tracked by satellites (WGS84/ITRF).

Warning: Raw GPS to CAD Coordinate Discrepancy

Combining uncorrected WGS84 drone data with NAD83 site plans creates a structural shift of 1-2 meters. Review the massive legal implications of this error.

Explore Boundary Dispute Liability

2. Why GDA2020 Was Created

To align with modern GNSS (GPS) systems utilized by autonomous tractors, drones, and smartphones, the Australian government implemented GDA2020. This updated plate-fixed datum securely anchors local coordinates back in sync with global satellite readings for the year 2020.

Official Government Policy: Western Australia and NSW transitional policies explicitly instruct users to expect and accept a ~1.8 m difference when converting coordinates. Mixing GDA94 and GDA2020 datasets without transformation routinely misplaces underground utilities, farm boundaries, and mining infrastructure.

3. Transformation: National Transformation Grids

To convert between GDA94 and GDA2020, Geoscience Australia provides two official grid transformation files (NTv2):

Professional Risk Notice

Using the wrong datum or applying coordinates without grid-to-ground correction can cause 1-400 metre positional errors —a leading cause of surveying negligence claims and contract disputes.

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Access 座標変換ツール Test Error in Reality シミュレーター

重要：計算結果の正確性を確認してください

座標精度はデバイスや測地系によって異なります。以下の確認を行わずに実務で使用しないでください：

GPS精度の警告

スマホのGPSは最大30メートルずれることがあります。これが原因でデータに重大なエラーが発生します。

精度を今すぐチェック →

測地系のリスク

誤った測地系（例：WGS84と日本測地系）を使用すると、常に数百メートルのズレが生じます。

測地系を確認する →