Jump to the following:

Ordnance Survey logo

Discover Ordnance Survey

Skip primary navigation
Site Search
Skip secondary navigation

Questions - abstract imageKnowledgeBase

Definitive information on popular topics relating to maps and geography.

Property boundaries and who records them
We and Land Registry work in very close partnership. Land Registry cross-references and associates their boundary information with our topographic maps as the basis of all Land Registry title plans.

Satnav systems and our data
Learn about our role in the market, what information we capture, who recommends which route you should take, issues around accuracy and postcodes, and how to report errors on your satnav maps.

The National Grid
What the National Grid is, how it works, its history, true and false geographical origins and links to useful tools.

Grid North, Magnetic North and True North
Understand the difference between grid north, magnetic north and true north and how to calculate magnetic declination.

Calculating distances using National Grid references
Learn how to combine the National Grid with Pythagoras' Theorem to calculate distances between two points by following our worked example.

Finding your height above sea level
Learn how to use our 1:25 000 scale OS Explorer paper map or the OS getamap website, which displays it online, to find the height of a spot above sea level using contour lines.

 

Free resources
Download or order map datasets, sample data, map-reading leaflets, outline maps, symbol sheets, outline maps and more - all freely-available on our website.

Historical map archive dispersal
Our historical mapping archive has been dispersed to various public libraries around the country. A number of retailers also supply historical mapping.

The origins of place names in Scotland and Wales
Learn how the origins of place names in Scotland or Wales were influenced by or are directly attributable to the Gaelic, Scandinavian, Scots and Welsh languages.

Historic instructions to draftsmen, plan and field examiners
Find out the standards to which draftsmen, plan and field examiners worked a century ago from these instructions, published in 1905 and 1906.

Field parcel numbers
Learn where to obtain field parcel numbers and measurements.

Mapping for emergencies
About the free service we provide to the emergency services whenever there is a threat to or loss of life.

Skip supplementary navigation

For general enquiries, complaints, feedback or suggestions, email: customerservices@ordnancesurvey.co.uk or call us on 08456 05 05 05