Coordinate

TUREF, UTM, ITRF: how to choose the right coordinate system in Türkiye

14 min read June 10, 2026

A good field point is not enough. The reference frame, zone and units matter just as much. Modern work in Türkiye commonly uses TUREF-based projected coordinates, while older archives may still contain ED50.

Field takeaways

  • A coordinate reference system is more than a projection name; datum, ellipsoid, units and EPSG code matter.
  • TUCBS lists TUREF/TM27 to TUREF/TM45 as EPSG:5253 to EPSG:5259.
  • 3-degree Gauss-Kruger zones are separate records, listed as EPSG:5269 to EPSG:5275.
  • ED50 to TUREF is not a casual shift. Transformation quality depends on method and control.
  • Keep the EPSG code with MapLab Survey exports to reduce CAD/GIS placement errors.

Datum and projection are different

A coordinate reference system is not only a name. Datum, ellipsoid, unit, projection parameters and EPSG code all matter. TUREF and ED50 belong to the reference side; TM and UTM describe projected coordinates.

Why TUREF matters

Modern surveying deliverables in Türkiye often expect TUREF/TM coordinates in metres. A GNSS receiver can observe in a global frame, but the project file usually needs a specific national CRS and zone.

Zones and EPSG codes

TUCBS lists TUREF / TM27 to TUREF / TM45 as EPSG:5253 to EPSG:5259. It also lists separate 3-degree Gauss-Kruger zones as EPSG:5269 to EPSG:5275. Write the EPSG code in delivery notes.

ED50 needs care

Older ED50 data should not be moved with a casual shift. HGM's ED50 to TUREF study shows that transformation quality depends on method, control point distribution and legacy network quality.

Practical MapLab Survey rule

Before measuring, write down reference frame, projection/zone, units and elevation reference. Use EPSG codes where possible, then test on known control points.

In the field · MapLab Survey

Measure, check and deliver in the right format.

MapLab Survey is a mobile field app for RTK/GNSS points, drawings, area/volume calculations, coordinate conversion and export to DXF, KML/KMZ, GeoJSON and CSV. Capture, calculation and export can work offline; live NTRIP corrections and online basemaps need connectivity.

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Frequently asked questions

Why use EPSG codes?

They identify the CRS more clearly than a name alone.

Are TUREF and WGS84 the same?

They should not be treated as identical in precise work.

What is EPSG:5254?

It is TUREF / TM30 in the TUCBS record.

How should ED50 be handled?

Use known transformation parameters, reliable shared control or an official workflow.

Technical references

The field guidance in this article is aligned with the technical and official references below.

Related: ED50 to TUREF · Transformation report · TUCBS CRS · MapLab Survey