GGRS87 (Greek Geodetic Reference System 1987)
Nov 5,2025

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Introduction

GGRS87 (Greek Geodetic Reference System 1987) is a geodetic reference system for geographic information processing covering the whole of Greece. Its EPSG code is 4120 and is widely used for domestic spatial information management, primarily for topographic mapping, surveying, cadastral management, and infrastructure development. This coordinate system is designed to optimize positional accuracy within the Greek territory while maintaining high compatibility with the European Geodetic System (ETRS89) and the World Geodetic System (WGS84).

Coordinate System Composition

Geodetic Datum: GGRS87 (Greek Geodetic Reference System 1987)
Ellipsoid: GRS80 (Geodetic Reference System 1980)
Projection Method: National grid (HGRS87 / Greek Grid) based on the Helmert Transverse Mercator method
Central meridian: 24°E
Unit: Meters (plane Cartesian coordinate system)
Coverage area: All of Greece's mainland and islands

Pros

It has high surveying accuracy within Greece and is suitable for cadastral surveys and urban planning.
It uses the GRS80 ellipsoid, making it easy to convert to international coordinate systems.
It is widely used by government agencies and private companies as a unified national geodetic standard.

Cons

Accuracy is poor outside of Greece, making it unsuitable for wide-area applications.
Older data may not have updated geodetic standards, which may result in errors during integration.
Some global GIS services do not directly support this data, and conversion work may be required.

Application Scenario

GGRS87 (EPSG:4120) is the standard geodetic reference system used for spatial information management in Greece. It is essential for land management and urban development, including cadastral surveys, road and railway network design, water supply and sewerage and communication infrastructure planning, and environmental monitoring. It is also used to create detailed maps of tourist destinations and island areas, and by sharing a consistent location information platform between the government and private sector, it contributes to disaster prevention measures and the efficiency of public services. When exchanging data internationally, coordinate conversion with ETRS89 or WGS84 ensures consistency with global GIS systems.