The OS National Geographic Database (NGD) and MasterMap® are closely related — but they are not the same thing.

If you work with professional Ordnance Survey data, understanding the distinction is important for planning, engineering and GIS workflows.

This article explains:

• What the OS NGD is

• What MasterMap® is

• How they relate

• What professionals actually download from MapServe®

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Quick Answer

• OS NGD is the core national geospatial database maintained by Ordnance Survey.

• MasterMap® is a product derived from that database.

• Professionals access structured extracts of this data via licensed suppliers such as MapServe®.

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What Is the OS National Geographic Database (NGD)?

The OS National Geographic Database (NGD) is the central geospatial data repository maintained by Ordnance Survey.

It contains structured, object-level data representing:

• Buildings

• Roads

• Rail infrastructure

• Land parcels

• Water features

• Boundaries

• Terrain

The NGD is not a downloadable “map.”
It is a continuously maintained spatial database.

You can learn more about professional Ordnance Survey datasets here:

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What Is MasterMap®?

MasterMap® is a commercial product derived from the NGD.

It provides:

• Large-scale, detailed topographic mapping

• Structured vector data

• Layered thematic datasets

• Survey-grade positional accuracy

Each mapped feature includes a TOID (Topographic Identifier), allowing integration into GIS systems and asset management platforms.

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The Key Difference

The simplest way to understand it:

The NGD is the source.
MasterMap® is a structured output.

_{OS NGD sample vs OS MasterMap® sample}

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How Professionals Access the Data

Professionals do not directly access the raw NGD.

Instead:

1. Ordnance Survey maintains the NGD.

2. Licensed partners access the data under agreement.

3. Site-specific extracts are generated.

4. The mapping is supplied in usable formats.

When you download OS maps from MapServe®, you are receiving licensed extracts derived from the NGD, commonly delivered as:

• DWG

• DXF

• PDF

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Is NGD Replacing MasterMap®?

No.

The NGD is the underlying database framework.
MasterMap® remains a structured commercial dataset derived from that framework.

Think of the NGD as the engine.
MasterMap® is one of the primary outputs.

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Where 1:1250 and 1:2500 Mapping Fit In

Large-scale mapping products such as:

• 1:1250

• 1:2500

are also derived from the NGD.

These are typically used for:

• Planning applications

• Site location plans

• Block plans

Professional planning drawings are based on NGD-derived datasets supplied via licensed providers.

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Why This Distinction Matters

Understanding the NGD vs MasterMap® distinction matters because:

• It clarifies what you are licensing

• It explains how updates flow into datasets

• It reinforces why OS mapping is authoritative

• It supports compliance in professional workflows

The data originates from a continuously maintained national geospatial database, not static mapping files.

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Frequently Asked Questions

Is MasterMap® the same as NGD?

No. NGD is the national database; MasterMap® is a commercial dataset derived from it.

Can I download the NGD directly?

No. Professionals download licensed extracts derived from NGD datasets via suppliers such as MapServe®.

Is MasterMap® being discontinued?

No. It continues as a structured product derived from NGD data.

Are planning maps based on NGD data?

Yes. 1:1250 and 1:2500 mapping products are derived from NGD datasets.

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Conclusion

The OS National Geographic Database (NGD) is the foundational geospatial database maintained by Ordnance Survey.

MasterMap® is a structured commercial dataset derived from that database and supplied to professionals via licensed providers such as MapServe®.

If you require authoritative OS mapping derived from NGD datasets, you can download licensed mapping directly from MapServe®.