List of motorways in the United Kingdom

List of motorways in the United Kingdom is a complete list of motorways in the United Kingdom. Note that while one numbering scheme is used for Great Britain, roads in Northern Ireland are allocated their own numbers on an ad hoc basis.

Former motorways
Roads which used to be motorways but have been downgraded:

Unbuilt motorways
There have been many plans for motorways in the UK that have not been built. Below is a list of plans that weren't built (not exhaustive):
 * M12 in 3 forms :
 * From the London end of the M11 to Brentwood;
 * From the London end of the M11 to Maplin Sands Airport (also not built);
 * From the M25 (in the vicinity of the M11) to Chelmsford.
 * M13, from East London to Maplin Sands airport passing south of Southend.
 * M17 Castle Donington bypass, a short spur off the M1;
 * M31, a bypass of the busiest section of the M25, cutting the corner for traffic from the West.
 * M59, M58 junction 2 to south of Preston.
 * M64, between the M6 south of Stoke-on-Trent and the M1 near Derby. Mostly built as the A50.
 * M601, which would have entered Manchester from the M62 (now the M60) near Pendlebury.
 * M650, Airedale Motorway from near Silsden to Shipley.
 * A6(M) (or M66 extension), which would have formed an eastern bypass for Stockport. As of March 2006, this is still under the planning stage as part of the SEMMMS (south east Manchester multi modal study) project (though not as motorway).
 * A556(M), which would have cut the corner between the M6 and M56 near Warrington.
 * Chippenham Spur, off the M4
 * Strensham - Solihull motorway, a link between the M50 and M42 or M69

Many cities had urban motorway plans, most of which were not built. London, Newcastle, Liverpool, Manchester/SELNEC and Glasgow all had extensive plans.

Unbuilt motorways
The following motorways were planned, but never built.
 * M11, from the M1 going through Lisburn and then crossing the M1 again and ending at Newry
 * M23, from the M2 to Derry

There were also urban motorway plans for Belfast