How big is the United Kingdom's transmission network?

OverWatts maps 9,612 km of transmission line in the United Kingdom, across 7,171 segments, plus 233 substations. This is mapped length from OpenStreetMap, not an operator-reported total — where OSM is incomplete the figure is a floor, never a ceiling.

What voltage is the United Kingdom's grid?

Most of the mapped network is extra-high voltage (380–764 kV): 6,715 km of 9,612 km. The highest voltage tagged anywhere in the country is 400 kV.

Who operates the grid in the United Kingdom?

National Grid Electricity Transmission, National Grid, SP Energy Networks and 5 others are tagged as operators on mapped segments. Operator tags are present on 24% of the United Kingdom's segments, so this ranks who is *recorded*, not market share.

What interconnectors connect the United Kingdom to its neighbours?

7,030 MW of cross-border transfer capacity to France, Norway, Belgium, Netherlands, Ireland, plus 20,045 MW planned. Capacities are from the Global Transmission Database (v1.0, 2023); flow over the GB cables is published live every five minutes by Elexon.

United Kingdom · electricity network

United Kingdom power grid

OverWatts maps 9,612 km of the United Kingdom's electricity transmission network across 7,171 line segments and 233 substations, the 36th most-mapped grid of 153 countries. Its backbone is extra-high voltage (380–764 kV), carrying 6,715 km — 70% of the mapped length, with the highest tagged voltage at 400 kV. That works out to 38.6 km per 1,000 km² of land — strong OpenStreetMap coverage, ahead of 78% of mapped countries. It is connected to 5 neighbouring grids by 7,030 MW of existing cross-border transfer capacity, with a further 20,045 MW planned.

Open the grid lens →United Kingdom profile →

9,612 km

Mapped transmission line

233

Substations

#36

of 153 mapped grids

7.0 GW

cross-border · 5 neighbours

400 kV

Highest voltage

OpenStreetMap coverage

Strong38.6 km / 1,000 km²ahead of 78% of 153 mapped countries

This grades how completely OpenStreetMap has drawn the United Kingdom's network — not how much network exists. Large, sparsely-populated countries score low for geographic reasons alone, and every kilometre here is mapped length, so the totals are a floor rather than an operator-reported figure. 11% of segments carry a real line name and 24% an operator tag.

Mapped line length by voltage

380–764 kV6,715 km 70%
220–379 kV2,878 km 30%
Voltage untagged19 km 0%

7,171 segments · a segment is credited to the country containing its midpoint, so a border-crossing line counts once, on one side.

7.0 GW existing · 20.0 GW planned · capacities from the Global Transmission Database v0.1 (CC BY 4.0), existing as of 2023 · GB cable flow every five minutes · Contains BMRS data © Elexon Limited copyright and database right 2026

On the interactive map

Open the interactive map →

Load against the network

67.5 GW

Operating generation

Data centres mapped

km of line per substation

38.6

km per 1,000 km²

Where there is room to connect a new load depends on published hosting capacity, which most operators release only as their own map. OverWatts does not yet ingest those feeds, so these are the density measures the open data supports — generation and mapped demand against mapped network — not a headroom figure.

Segment counts from OSM `operator` tags, merged across spellings. Present on 24% of segments — this ranks who is recorded, not market share.

How the United Kingdom compares · mapped grid by country

1. People's Republic of China624,300 km
34. Libya11,200 km
35. Ethiopia9,988 km
36. United Kingdom9,612 km
37. Norway8,900 km
38. Romania7,845 km

Frequently asked

How big is the United Kingdom's transmission network?: OverWatts maps 9,612 km of transmission line in the United Kingdom, across 7,171 segments, plus 233 substations. This is mapped length from OpenStreetMap, not an operator-reported total — where OSM is incomplete the figure is a floor, never a ceiling.
What voltage is the United Kingdom's grid?: Most of the mapped network is extra-high voltage (380–764 kV): 6,715 km of 9,612 km. The highest voltage tagged anywhere in the country is 400 kV.
How complete is the grid map for the United Kingdom?: Strong — 38.6 km of mapped line per 1,000 km² of land, ahead of 78% of the 153 countries with any mapped grid. Coverage grades how completely OpenStreetMap has drawn the network, not how much network exists; large, sparsely-populated countries score low for geographic reasons alone.
Who operates the grid in the United Kingdom?: National Grid Electricity Transmission, National Grid, SP Energy Networks and 5 others are tagged as operators on mapped segments. Operator tags are present on 24% of the United Kingdom's segments, so this ranks who is *recorded*, not market share.
What interconnectors connect the United Kingdom to its neighbours?: 7,030 MW of cross-border transfer capacity to France, Norway, Belgium, Netherlands, Ireland, plus 20,045 MW planned. Capacities are from the Global Transmission Database (v1.0, 2023); flow over the GB cables is published live every five minutes by Elexon.

Elsewhere in the United Kingdom

Transmission lines Substations Power plants Data centres

Network geometry: OpenStreetMap (ODbL) © OpenStreetMap contributors, ingested and measured by OverWatts · derived 2026-07-26. Counts every mapped line of 220 kV and above; the map layer draws the ≥380 kV backbone only, so it shows less than is measured here.