Country Coordinate Systems
Ain el Abd 1970 Datum (Saudi Arabia)
Summary
Ain el Abd 1970 is a classical geodetic datum on the International 1924 ellipsoid, used for older mapping in Saudi Arabia, Kuwait and Bahrain. Its geographic CRS is EPSG:4204 and UTM zones 37N–40N are EPSG:20437–20440. Coordinates differ from WGS 84 and KSA-GRF17 by tens of metres, and the EPSG transformation for Saudi Arabia is accurate to only about 18 m.
Definition
Ain el Abd 1970: a geodetic datum with its origin at Ain el Abd (Saudi Arabia) on the International 1924 (Hayford) ellipsoid.
- Ellipsoid: International 1924
- a = 6 378 388 m, 1/f = 297
- Geographic: EPSG:4204
- UTM 37N–40N: EPSG:20437–20440
EPSG codes
| EPSG | Name | Area of use |
|---|---|---|
| 4204 | Ain el Abd | Bahrain, Kuwait and Saudi Arabia onshore |
| 20437 | Ain el Abd / UTM zone 37N | Saudi Arabia 36°E–42°E |
| 20438 | Ain el Abd / UTM zone 38N | Kuwait west of 48°E; Saudi Arabia 42°E–48°E |
| 20439 | Ain el Abd / UTM zone 39N | Kuwait east of 48°E; Saudi Arabia 48°E–54°E |
| 20440 | Ain el Abd / UTM zone 40N | Saudi Arabia east of 54°E |
Transformations to WGS 84
| Transformation | Parameters | Area | Accuracy |
|---|---|---|---|
| Ain el Abd to WGS 84 (2) | tX −143, tY −236, tZ +7 m | Saudi Arabia | 18 m |
| Ain el Abd to WGS 84 (1) | tX −150, tY −250, tZ −1 m | Bahrain | 44 m |
| Ain el Abd to WGS 84 (3)–(6) | 3- and 7-parameter sets | Kuwait (regional) | 1 m |
For engineering work in Saudi Arabia, derive local parameters from points known in both Ain el Abd and KSA-GRF17, and document them.
Worked example
At Riyadh the EPSG default transformation places the same physical point +65.6 m in easting and -12.5 m in northing from its WGS 84 / UTM 38N position.
FAQ
Is Ain el Abd still used?
Yes, in legacy drawings, cadastral records and some oil and gas datasets. New national work uses KSA-GRF17.
Why can’t I get centimetre agreement converting Ain el Abd to WGS 84?
The published EPSG transformation for Saudi Arabia has 18 m accuracy. Only locally fitted parameters can do better.
Related tools and articles
Tools
- Saudi Arabia ConverterKSA-GRF17, Ain el Abd and UTM zones.
- Coordinate TransformationConvert between EPSG coordinate systems.
Articles
- KSA-GRF17: Saudi Arabia Geodetic Reference FrameKSA-GRF17 is the national geodetic reference frame of Saudi Arabia, defined by GEOSA and aligned to ITRF2014 a…
- Datum Transformations: Helmert, Grids and AccuracyA datum transformation converts coordinates between two geodetic datums, for example Ain el Abd 1970 to WGS 84…
- Saudi ArabiaReference topic
- UTM Coordinate System ExplainedUTM divides the world between 80°S and 84°N into 60 zones, each 6° of longitude wide and projected with a Tran…
References
- IOGP. EPSG Geodetic Parameter Dataset, epsg.org.
- IOGP. Geomatics Guidance Note 7-2: Coordinate Conversions and Transformations including Formulas, IOGP Report 373-7-2.
Cite this page
GeoCAD Bridge. “Ain el Abd 1970 Datum (Saudi Arabia).” GeoCAD Bridge Knowledge Center, updated 2026-10-05. https://www.geocadbridge.com/knowledge/coordinate-systems-saudi-ain-al-abd/