Convert Hong Kong 1980 to WGS 84
Old plan, map or survey in Hong Kong 1980 (Hong Kong)? Convert the coordinates to WGS 84 (the GPS reference) and back, in latitude/longitude, UTM or the local grid, and see how far each point moves.
Result
Paste the points above.
Datums and parameters
Each legacy datum has its own ellipsoid and origin. The coordinate is converted to X, Y, Z (geocentric), receives the transformation published in the EPSG registry (3-parameter translation or 7-parameter Helmert) and goes back to latitude/longitude on the target ellipsoid. The grids (UTM and national) are computed with the right ellipsoid on each side.
| Datum | Countries | Ellipsoid | Parameters to WGS 84 | Accuracy | Source |
|---|---|---|---|---|---|
| PSAD56 | Peru, Venezuela, Ecuador, Bolivia… | International 1924 | -279 · 175 · -379 | ±16 m | EPSG:1208 |
| Campo Inchauspe | Argentina | International 1924 | -148 · 136 · 90 | ±9 m | EPSG:1127 |
| Bogotá 1975 | Colombia | International 1924 | 307 · 304 · -318 | ±10 m | EPSG:1125 |
| NAD27 | Mexico, Guatemala, Belize, El Salvador… | Clarke 1866 | -12 · 130 · 190 | ±12 m | EPSG:1187 |
| SAD69 | Brazil, Chile, Argentina, Paraguay… | GRS 1967 Modified | -57 · 1 · -41 | ±19 m | EPSG:1864 |
| Yacaré | Uruguay | International 1924 | -124.45 · 183.74 · 44.64 · -0.4384 · 0.5446 · -0.9706 · -2.1365 | ±1.5 m | EPSG:5386 |
| Chua | Paraguay, Brazil | International 1924 | -134 · 229 · -29 | ±12 m | EPSG:1131 |
| Ocotepeque 1935 | Guatemala, El Salvador, Honduras, Nicaragua… | Clarke 1866 | 213.116 · 9.358 · -74.946 · 2.351418791 · -0.061466912 · 6.394208994 · 5.22 | ±5 m | EPSG:6889 |
| Minna | Nigeria, Cameroon | Clarke 1880 (RGS) | -92 · -93 · 122 | ±15 m | EPSG:1168 |
| Arc 1960 | Kenya, Tanzania, Uganda, Burundi | Clarke 1880 (RGS) | -157 · -2 · -299 | ±6 m | EPSG:1284 |
| Arc 1950 | Zambia, Zimbabwe, Botswana, Malawi | Clarke 1880 (Arc) | -143 · -90 · -294 | ±44 m | EPSG:1113 |
| Cape | South Africa, Lesotho, Eswatini, Botswana… | Clarke 1880 (Arc) | -136 · -108 · -292 | ±9 m | EPSG:1128 |
| Hartebeesthoek94 | South Africa, Lesotho, Eswatini, Namibia | WGS 84 | 0 · 0 · 0 | ±1 m | EPSG:1505 |
| Adindan | Sudan, South Sudan, Ethiopia, Eritrea | Clarke 1880 (RGS) | -161 · -14 · 205 | ±7 m | EPSG:1106 |
| Point 58 | Burkina Faso, Niger | Clarke 1880 (RGS) | -106 · -129 · 165 | ±44 m | EPSG:1880 |
| Merchich | Morocco, Western Sahara | Clarke 1880 (IGN) | 31 · 146 · 47 | ±7 m | EPSG:1166 |
| Nord Sahara 1959 | Algeria | Clarke 1880 (RGS) | -267.407 · -47.068 · 446.357 · -0.179423 · 5.577661 · -1.27762 · 1.204866 | ±1 m | EPSG:10296 |
| Carthage | Tunisia | Clarke 1880 (IGN) | -263 · 6 · 431 | ±14 m | EPSG:1130 |
| Camacupa 1948 | Angola | Clarke 1880 (RGS) | -50.9 · -347.6 · -231 | ±5 m | EPSG:1327 |
| Tete | Mozambique | Clarke 1866 | -80 · -100 · -228 | ±17 m | EPSG:6901 |
| Egypt 1907 | Egypt | Helmert 1906 | -127.535 · 113.495 · -12.7 · 1.603747 · -0.153612 · -5.364408 · 5.33745 | ±1.2 m | EPSG:7697 |
| Accra | Ghana | War Office | -170 · 33 · 326 | ±6 m | EPSG:6896 |
| Leigon | Ghana | Clarke 1880 (RGS) | -130 · 29 · 364 | ±5 m | EPSG:1159 |
| Ain el Abd 1970 | Saudi Arabia, Kuwait, Bahrain | International 1924 | -143 · -236 · 7 | ±18 m | EPSG:1111 |
| Nahrwan 1967 | United Arab Emirates, Qatar, Saudi Arabia, Oman | Clarke 1880 (RGS) | -249 · -156 · 381 | ±44 m | EPSG:1191 |
| Deir ez Zor | Syria, Lebanon | Clarke 1880 (IGN) | -190.421 · 8.532 · 238.69 | ±5 m | EPSG:15742 |
| Palestine 1923 | Israel, Palestine, Jordan | Clarke 1880 (Benoit) | -229 · -67 · 277 | ±2.5 m | EPSG:8650 |
| Karbala 1979 | Iraq | Clarke 1880 (RGS) | 70.995 · -335.916 · 262.898 | ±1 m | EPSG:5078 |
| FD58 | Iran | Clarke 1880 (RGS) | -241.54 · -163.64 · 396.06 | ±0.5 m | EPSG:1513 |
| Qatar 1974 | Qatar | International 1924 | -128.033 · -283.697 · 21.052 | ±1 m | EPSG:1563 |
| Tokyo | Japan, South Korea | Bessel 1841 | -146.414 · 507.337 · 680.507 | ±9 m | EPSG:15484 |
| Indian 1975 | Thailand | Everest 1830 (1937 Adjustment) | 293 · 836 · 318 · 0.5 · 1.6 · -2.8 · 2.1 | ±3 m | EPSG:1812 |
| Indian 1954 | Thailand, Myanmar | Everest 1830 (1937 Adjustment) | 217 · 823 · 299 | ±21 m | EPSG:1153 |
| VN-2000 | Vietnam | WGS 84 | -191.90441429 · -39.30318279 · -111.45032835 · -0.00928836 · 0.01975479 · -0.00427372 · 0.252906278 | ±1 m | EPSG:6960 |
| Kertau 1968 | Malaysia, Singapore | Everest 1830 Modified | -11 · 851 · 5 | ±15 m | EPSG:1158 |
| ID74 | Indonesia | Indonesian National Spheroid | -1.977 · -13.06 · -9.993 · -0.364 · -0.254 · -0.689 · -1.037 | ±3 m | EPSG:1833 |
| Luzon 1911 | Philippines | Clarke 1866 | -133 · -77 · -51 | ±17 m | EPSG:1161 |
| Hong Kong 1980 | Hong Kong | International 1924 | -162.619 · -276.959 · -161.764 · -0.067753 · 2.243648 · 1.158828 · -1.094246 | ±1 m | EPSG:1825 |
| Indian 1960 | Vietnam, Cambodia | Everest 1830 (1937 Adjustment) | 198 · 881 · 317 | ±44 m | EPSG:1542 |
| Pulkovo 1942 | Russia, Ukraine, Belarus, Kazakhstan… | Krassowsky 1940 | 23.57 · -140.95 · -79.8 · 0 · -0.35 · -0.79 · -0.22 | ±3 m | EPSG:5044 |
| Pulkovo 1942 | Poland, Romania, Albania, Germany | Krassowsky 1940 | 33.4 · -146.6 · -76.3 · -0.359 · -0.053 · 0.844 · -0.84 | ±1 m | EPSG:1645 |
| ED50 | Spain, Portugal, Italy, Greece… | International 1924 | -87 · -98 · -121 | ±10 m | EPSG:1133 |
| GGRS87 | Greece | GRS 1980 | -199.87 · 74.79 · 246.62 | ±1 m | EPSG:1272 |
| Monte Mario | Italy, San Marino, Vatican City | International 1924 | -104.1 · -49.1 · -9.9 · 0.971 · -2.917 · 0.714 · -11.68 | ±4 m | EPSG:1660 |
| S-JTSK | Czechia, Slovakia | Bessel 1841 | 570.8 · 85.7 · 462.8 · 4.998 · 1.587 · 5.261 · 3.56 | ±1 m | EPSG:1623 |
ΔX, ΔY, ΔZ in metres; with 7 parameters, also the rotations (arc-seconds) and the scale (ppm), in the convention of the EPSG method shown. The accuracy is the one given by EPSG for the transformation: from a few decimetres to tens of metres. For precise work, use the official parameters or grids of the country's mapping agency.
FAQ
What is a datum and why does the coordinate change?
The datum is the “reference” of the coordinate: the ellipsoid and its position relative to the Earth. Legacy datums (such as PSAD56, Minna or Tokyo) were fitted to one country or continent; WGS 84, used by GPS, is global. The same point on the ground has a different latitude and longitude in each datum — the difference is usually tens to hundreds of metres.
How accurate is this conversion?
It is the accuracy of the transformation published in the EPSG registry, shown with every result: from the best (under 1 m, with national 7-parameter sets) to regional means (5 to 25 m). It is good for finding old points in the field, overlaying plans and maps and checking surveys. For cadastral or precise work, use the official parameters or grids of the country's mapping agency.
Are WGS 84 and the modern frames (SIRGAS, POSGAR, MAGNA-SIRGAS, Hartebeesthoek94, ITRF) the same thing?
For everyday work, yes: they all agree with WGS 84 within a few centimetres to 1 metre. So the WGS 84 result can be used as the country's modern frame at that level of accuracy.
How do I know which datum my plan or map uses?
Look at the title block, the legend or the notes (“Datum”, “Horizontal datum”, “Reference system”). The date helps too: plans made before GPS were almost always in the old national datum. If in doubt, convert a known point and compare it with a GPS measurement.
Does my data leave my computer?
No. The conversion runs entirely in your browser; no coordinate is sent to the server.