OS MasterMap Topography Layer

OS MasterMap Topography Layer® is the most detailed and accurate view of Great Britain's landscape – from roads to fields, to buildings and trees, fences, paths and more.


In a business of any kind, OS MasterMap Topography Layer gives you the confidence to make location-based decisions about assets, services, environmental risks, customers and operations.

It helps you carry out effective scenario planning, improve resilience, manage public events and support security operations.

And for every type of business, OS MasterMap Topography Layer helps you to identify the landscape and explain the accurate ‘where’ of things.

Mapping from the ground up

OS MasterMap Topography Layer gives you access to the most detailed, current and comprehensive dataset of Great Britain. It offers an accurate visual context to help you interpret addresses, routes and imagery provided by other layers.

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New! Building height Beta data

OS MasterMap Topography Layer now includes an enhanced feature - Building Height Attribute. Visualise buildings in 3D and use our data to analyse the built environment.

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New! Upgrade of descriptive terms in progress

Enhanced descriptive terms for land, water and structures now being released.

View release plan and more information

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Accurate referencing

OS MasterMap Topography Layer is ideal for geo-tagging your assets, thanks to the topographic identifier (TOID®) at the heart of OS MasterMap products. This makes it ideal for monitoring assets such as pipelines, pylons, bridges and warehouses.

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Detail and flexibility

Start by using OS MasterMap Topography Layer as a definitive map for visualisation, then take advantage of advanced features later. With this data, you’ll make better-informed decisions about customers, operations, assets and environmental risks.

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Enriched content in urban areas

Over the longer term, we're enhancing the detail of OS MasterMap Topography Layer in towns and cities to give you even more value from the the product. See our progress.

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Important sites mapped out

OS MasterMap Sites Layer shows you the main points of access to key sites such as schools, hospitals and train stations quickly and easily in emergency situations. You can also identify and reduce the impact of planned works or events on key sites.


Key featuresWhat this product offers
  • OS MasterMap Topography Layer – buildings, heritage & antiquities.
  • OS MasterMap Sites Layer – education, medical care, rail transport, road transport, water transport, utility, and industrial.
Update frequency
  • OS MasterMap Topography Layer – every six weeks (view release schedule) thanks to continuous and cyclic revision.
  • OS MasterMap Sites Layer – every six months.
  • Building Height Attribute – this is an alpha release currently under development.
  • OS MasterMap Topography Layer – Great Britain (define your own area of interest or take advantage of pre-defined areas of interest).
  • OS MasterMap Sites Layer – Great Britain (order 5km2 tiles to cover your Topography Layer area of interest).
  • Building Height Attribute – please see our interactive coverage map.
  • OS MasterMap Topography Layer – GML 2.1.2
  • OS MasterMap Sites Layer – GML 3.2.1
  • Building Height Attribute – CSV
  • OS MasterMap Topography Layer and Sites Layer – FTP (for orders under 2Gb) and DVD.
  • Building Height Attribute – Members of mapping agreements can download this from the members' area. Partners and direct customers should contact their account manager.
Data structure

Vector (points, lines, polygons and text).


1:1250 to 1:10 000

OS MasterMap Topography Layer support ›


How is this data supplied and what do I need to use it?

OS MasterMap Topography Layer is supplied on DVD. If the file size of your order is smaller than 2 Gb, you can get it from our FTP server.

If you're in the PSMA or OSMA, you can download Building Height Attribute data from the members' area. Partners and commercial customers: please contact your Account Manager.

You'll need geographic information system (GIS) software to use Topography Layer.

How often is the OS MasterMap Topography Layer updated?

How often is the OS MasterMap Topography Layer updated?

All OS MasterMap® datasets are created from a single master dataset, which is refreshed regularly. Currently, the refresh period for Topography Layer supply is every six weeks (view release schedule).

OS MasterMap Topography Layer works on the principle that you will take an initial supply of all data in your area of interest and then update the data by taking change-only update (COU).

COU brings your dataset up to date with the most recent OS MasterMap data available from Ordnance Survey.

The update of real world features within OS MasterMap Topography Layer depends on what Category of change the feature falls in, as described in our Basic scale revision pollcy.

How can I find out if a certain type of real-world object is represented in the Topography Layer?

Please see our real-world object catalogue (PDF). It lists every type of real-world object in the OS MasterMap Topography Layer specification, and details how it is represented by Topography Layer features.

What scale is OS MasterMap Topography Layer data?

For cartographic representation, OS MasterMap Topography Layer is captured and designed for display at 1:1250, 1:2500 and 1:10 000 scales in urban, rural and mountain/moorland areas respectively. In GIS OS MasterMap can be viewed over a considerable range of scales. The most scale-sensitive feature types, such as cartographic text and symbol features, are fixed in size and rapidly become less clear at smaller display scales (that is, when zoomed out).

OS MasterMap Topography Layer is also suitable for use in non–cartographic applications where the concept of scale is less applicable.

How accurate is OS MasterMap Topography Layer?

We define accuracy in three ways:

  • Absolute accuracy – how closely the coordinates of a point in the dataset agree with the coordinates of the same point on the ground (in the British National Grid reference system).
  • Relative accuracy – positional consistency of a data point or feature in relation to other local data points or features within the same or another reference dataset.
  • Geometric fidelity – the ‘trueness’ of features to the shapes and alignments of the objects they represent when testing the data according to the dataset specification against the ‘real world’ or reference dataset.

The following table represents the absolute and relative accuracy applicable to the scale at which the product was surveyed.

Original survey scale99% confidence level95% confidence levelRMSE*
Absolute Accuracy 0.9 m 0.8 m 0.5 m
Relative Accuracy +/- 1.1 m (up to 60 m) +/- 0.9 m (up to 60 m) +/- 0.5 m (up to 60 m)
Absolute Accuracy 2.4 m 1.9 m 1.1 m
Relative Accuracy +/- 2.5 m (up to 100 m) +/- 1.9 m (up to 100 m) +/- 1.0 (up to 100 m)
1:10 000
Absolute Accuracy 8.8 m 7.1 m 4.1 m
Relative Accuracy +/- 10.1 m (up to 500 m) +/- 7.7 m (up to 500 m) +/- 4.0 m (up to 500 m)

*RMSE (root mean squared error) is the square root of the mean of the squares of the errors between the observations.

See all FAQs for OS MasterMap Topography Layer ›


OS MasterMap Topography Layer is available under the following Licences:

Explore our data

You’re welcome to try out this data for free under our Data Exploration Licence.

Internal business use

When using OS data in your own business, you need our Framework Contract (Direct Customers) together with a data contract.

Creating products or services

To use this data commercially in your own products and services, or to distribute it, you will need to sign up to our Framework Contract (Partners) and a relevant defined use contract. This will vary depending on what you’re going to do with the data.

Collective mapping agreements

These products are available to members of public sector organisations under the following agreements:

Find out more in our Public sector licensing guide ›

This product is available under the:

  • Media Licence. We encourage the use of OS maps in the media – TV, films, print and online. Sign up free to give your consumers valuable context via an authoritative map.
  • Publishing licence. This is suitable for one-off publishing of maps in publications, on merchandising and websites.
View all licences ›

Case studies

Give it a try

Download a small area of OS MasterMap Topography Layer sample data

Or you can apply for a Data Exploration Licence to try out the real thing.

From 1 April, new prices will apply for this product. Learn more