# Coordinate systems

> Every grid GIMLabs supports, with its EPSG code and how exactly it converts to latitude and longitude.

This is the full list of grids a project or configuration can use. For how a
project picks its grid and how locations are read and placed in it, see
[Locations and site plans](/manage/map/locations-and-plans#coordinate-systems).

## Supported grids

Search the coordinate system picker by any of these: the country, the grid's
name or its EPSG code (with or without `EPSG:`). A grid shared by two
countries, such as LV95 in Switzerland and Liechtenstein, is listed under both.

| Country | Grid | EPSG code | Conversion to latitude/longitude |
| --- | --- | --- | --- |
| Worldwide | WGS84 (latitude/longitude) | `EPSG:4326` | Exact |
| United Kingdom (Great Britain) | OSGB36 (British National Grid) | `EPSG:27700` | About 2 m (datum shift, not OSTN15) |
| Austria | MGI / Austria GK West | `EPSG:31254` | About 1 m (datum shift) |
| Austria | MGI / Austria GK Central | `EPSG:31255` | About 1 m (datum shift) |
| Austria | MGI / Austria GK East | `EPSG:31256` | About 1 m (datum shift) |
| Belgium | Lambert 2008 | `EPSG:3812` | Exact (ETRS89) |
| Belgium | Lambert 72 | `EPSG:31370` | About 1 m (datum shift) |
| Croatia | HTRS96/TM | `EPSG:3765` | Exact (ETRS89) |
| Czechia | S-JTSK / Krovak East North | `EPSG:5514` | About 1 m (datum shift) |
| Estonia | L-EST97 | `EPSG:3301` | Exact (ETRS89) |
| Finland | ETRS-TM35FIN | `EPSG:3067` | Exact (ETRS89) |
| France | Lambert-93 | `EPSG:2154` | Exact (ETRS89) |
| Greece | GGRS87 / Greek Grid | `EPSG:2100` | About 1 m (datum shift) |
| Hungary | EOV | `EPSG:23700` | About 1 m (datum shift) |
| Ireland | ITM | `EPSG:2157` | Exact (ETRS89) |
| Ireland | Irish Grid (TM75) | `EPSG:29903` | About 1 m (datum shift) |
| Latvia | LKS-92 | `EPSG:3059` | Exact (ETRS89) |
| Liechtenstein | LV95 | `EPSG:2056` | About 1 m (datum shift) |
| Lithuania | LKS-94 | `EPSG:3346` | Exact (ETRS89) |
| Netherlands | RD New | `EPSG:28992` | About 1 m (datum shift) |
| Poland | PL-1992 | `EPSG:2180` | Exact (ETRS89) |
| Portugal | PT-TM06 | `EPSG:3763` | Exact (ETRS89) |
| Romania | Stereo70 | `EPSG:3844` | About 1 m (datum shift) |
| Slovakia | S-JTSK / Krovak East North | `EPSG:5514` | About 1 m (datum shift) |
| Slovenia | D96/TM | `EPSG:3794` | Exact (ETRS89) |
| Slovenia | D48/GK | `EPSG:3912` | About 1 m (datum shift) |
| Sweden | SWEREF99 TM | `EPSG:3006` | Exact (ETRS89) |
| Switzerland | LV95 | `EPSG:2056` | About 1 m (datum shift) |
| United Kingdom (Northern Ireland) | ITM | `EPSG:2157` | Exact (ETRS89) |
| United Kingdom (Northern Ireland) | Irish Grid (TM75) | `EPSG:29903` | About 1 m (datum shift) |
| Europe-wide | ETRS89 / UTM 28N | `EPSG:25828` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 29N | `EPSG:25829` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 30N | `EPSG:25830` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 31N | `EPSG:25831` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 32N | `EPSG:25832` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 33N | `EPSG:25833` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 34N | `EPSG:25834` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 35N | `EPSG:25835` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 36N | `EPSG:25836` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 37N | `EPSG:25837` | Exact (ETRS89) |
| Europe-wide | ETRS89 / UTM 38N | `EPSG:25838` | Exact (ETRS89) |

## What the conversion column means

- **Exact (ETRS89)**: the grid is on ETRS89 or a national realisation of it, so
  GIMLabs converts to latitude and longitude with no datum shift.
- **About 1 m (datum shift)**: the grid is on an older national datum, such as
  D48 (MGI 1901), MGI, S-JTSK, Amersfoort or CH1903+. GIMLabs uses the datum
  shift published in the EPSG database, which is good to about a metre against
  EPSG's best transformation. That is plenty for plotting holes on the map, but
  it is not a survey-grade conversion: national grid-shift files (NTv2) are not
  used.
- **British National Grid** uses the published Helmert shift rather than
  OSTN15, good to about 2 m.

Eastings and northings you enter or import are stored as written; the
conversion only affects where a location is drawn on the map and the latitude
and longitude shown beside it.

## Which grid to choose

- Use the grid your survey data is delivered in. Two grids for the same country,
  such as D96/TM and D48/GK in Slovenia or ITM and the Irish Grid in Ireland,
  give different numbers for the same point, so a file in the other one lands
  hundreds of metres out.
- Where a country has no national grid listed, use the **ETRS89 / UTM** zone for
  its longitude. Each zone covers 6 degrees: zone 31N is 0° to 6°E, 32N is 6°E
  to 12°E, 33N is 12°E to 18°E, and so on.
- If your organisation has a country set in Product OS, the picker suggests that
  country's national grid for new configurations and projects.

<Callout type="note" title="Czechia and Slovakia">
  S-JTSK / Krovak East North (EPSG:5514) gives negative eastings and northings,
  for example about E -742 806, N -1 043 010 in central Prague. Enter them with
  the minus sign.
</Callout>