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 your GNSS coordinates to OSGB36 National Grid.
Grid InQuest2 software, incorporating 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
If you are a developer and need access to OSTN15 transformation and the OSGM15 geoid model, read our Grid InQuestII Developers Pack.
Accuracy information for legacy data sets
Find out about the accuracy of our legacy control data: passive GPS stations, Ordnance Survey benchmarks and trigs.