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Technical

UTM (Universal Transverse Mercator)

A projection system dividing the Earth's surface into 60 zones, coordinating each in metres. Turkish cadastral maps and parcel coordinates are stored in UTM.

UTM (Universal Transverse Mercator) divides the Earth into 60 zones of 6° longitude each and projects each zone onto a plane using the cylindrical conformal transverse Mercator projection. Each zone's central meridian lies at its midpoint (e.g. Zone 36's centre is at 33° East).

Türkiye's UTM zones: Western Thrace + Aegean coast Zone 35 (26°-32° E), Marmara + Central Anatolia + western Mediterranean Zone 36 (32°-36° E), Eastern Anatolia + eastern Mediterranean Zone 37 (36°-40° E), GAP region Zone 38 (40°-44° E). Istanbul sits on the eastern edge of Zone 35 with most of it in Zone 36.

Reading coordinates: UTM coordinates come as (Easting, Northing) pairs. Easting is distance east from the zone's central meridian, offset by 500,000 m (to avoid negative values). Northing is distance north from the equator (Northern Hemisphere). Example: Taksim, İstanbul is approximately (660,000 E, 4,545,000 N) in Zone 35N.

When UTM vs. geographic?: UTM is useful for distance and area calculations (metric units); WGS84 geographic (degrees-minutes-seconds) is more common for GPS and general map applications. Türkiye's cadastral measurements under BÖHHBÜY prefer 3° Gauss-Krüger but 6° UTM is also accepted.

Examples

  • 1.An engineer in Ankara (Zone 36N) directly calculates a parcel's area in m² using UTM coordinates; doing the same in lat-lon would give square-degree units.
  • 2.A cadastral map is produced in ITRF96 datum with 3° Gauss-Krüger; transformation is required to overlay GPS-derived WGS84/UTM6° data.
  • 3.A drone ortophoto is saved in UTM Zone 36N (EPSG:32636); ArcGIS auto-detects layer projection.

Frequently Asked Questions

Can I use a projection other than UTM?expand_more
Yes. Türkiye's cadastre treats **3° Gauss-Krüger** as the BÖHHBÜY standard; 6° UTM is used in scientific/international contexts. Web maps (Google Maps, OSM) use **Web Mercator (EPSG:3857)**. The right choice depends on purpose: 3° GK for cadastre, UTM for general GIS.
How do I convert UTM coordinates to WGS84 lat-lon?expand_more
QGIS, ArcGIS, Google Earth, cs2cs command-line tool, and others do it automatically. Online: epsg.io/transform or cs2cs. Manual math conversion is complex (Redfearn formulas). Drozero always serves WGS84 geographic, auto-converting from UTM.
Which zone applies to a parcel on a zone boundary?expand_more
The zone where most of the parcel lies is preferred. If a parcel actually straddles two zones (rare), separate coordinates are given per zone, or **Zone Transition** is used for nearby merging. In practice TKGM picks a fixed zone at the provincial level: Zone 36N is standard for İstanbul.
What do N and S mean in UTM?expand_more
**N = Northern Hemisphere**, **S = Southern Hemisphere**. Since Türkiye is in the Northern Hemisphere, we always use N: Zone 35N, 36N, 37N, 38N. S is for South America, Australia etc. Northing values reference differently — N from the equator, S from 10,000,000 m.

Related Terms

WGS84 (World Geodetic System 1984)Coordinate SystemGIS (Geographic Information System)

Sources

  • • Large-Scale Map and Map Information Production Regulation (BÖHHBÜY)
  • • Defense Mapping Agency - UTM Grid Zone Reference (1989)
  • • EPSG Geodetic Registry - UTM Zones 32631-32660

Try the FAR/GCR calculator

Calculate total floor area, storey count and estimated unit count in seconds from parcel m² and zoning values.

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Last updated: 2026-04-24