The standard errors for OS Net base station coordinates are generally better than 0.008m in plan and 0.020m in height.
Download OS Net RINEX data
Accuracy of OS Net, OSTN15 and OSGM15
Find out about the accuracy of our OS Net stations and coordinate transformations
OS Net station coordinate accuracy
OSTN15/OSGM15 transformation accuracy
OSTN15 now defines OSGB36 National Grid – in conjunction with the OS Net stations.
You can consider OSTN15 to be somewhat error free. That is, when any GNSS positional errors are not included.
Agreement between OSTN15 and the old triangulation network stations is 0.1m rms (down to the third order) for Great Britain only.
The standard error in height of OSGM15 for each regional vertical datum are included in the table below. These errors are for OSGM15 only and do not include any GNSS heighting errors.
| Regional height datum | Standard error (m) |
| Great Britain | 0.008 |
| Orkney | 0.017 |
| Shetland | 0.018 |
| Outer Hebrides (Stornoway 15 datum) | 0.011 |
| Isle of Man | 0.030 |
Related information
Online OSTN15-OSGM15 transformation tool
Use this tool to transform between GNSS coordinates and OSGB36 National Grid and mean sea level-based heights.
Grid InQuest II software for OSTN15 and OSGM15
This software can help you transfer a single coordinate or multiple coordinates from one format to another.
OSTN15 and OSGM15 raw data files
Use our coordinate calculation tools and software, and access coordinate transformation resources for developers.
OS legacy control data
Search for passive stations, benchmarks, or triangulation stations, and find out about the accuracy of our legacy control data.