|Coordinates: 51°27′43″N0°10′08″W / 51.462°N 0.169°W|
|Postcode area name|
|Statistics as at May 2020 |
The SW (South Western) postcode area, also known as the London SW postcode area,  is a group of 20 postcode districts within the London post town in England. The area comprises the South Western operational district (covering the subdivisions of postcode district SW1, plus SW2 through SW10) and the Battersea operational district (covering SW11 through SW20),  and is the only area within the London post town to lie on both sides of the River Thames.
Mail for the area is sorted at the Jubilee Mail Centre in Hounslow, along with mail for the TW, KT and GU postcode areas.
The postcode area originated in 1857 as the SW district. In 1868 it gained some of the area of the very short-lived S district, with the rest going to SE. It was divided into numbered districts in 1917.  The South Western district consists of the postcode districts SW1–SW10 and the once Battersea-headquartered component consists of the postcode districts SW11–SW20.  
The South Western head district was designated as SW1 and the rest of the numbering followed, alphabetically, by their most important parish, chapelry, topological or built environment feature names, up to 10. Similarly as to the Battersea SW11 once "head district".
The approximate coverage of the postcode districts, with the historic postal district names shown in italics: 
|Postcode district||Post town||Coverage||Local authority area(s)|
|SW1A||LONDON||Whitehall, Buckingham Palace, the Houses of Parliament and west of St James's||Westminster|
|SW1E||LONDON||Northern 'Victoria' around Buckingham Gate (a street) to include both sides of part of Victoria Street||Westminster|
|SW1H||LONDON||Surrounds of St James's Park tube station centred on Broadway, Queen Anne's Gate and Old Queen Street to include both sides of part of Victoria Street – derivation: Horse Guards Parade||Westminster|
|SW1P||LONDON||A projection around Parliament Square. Nearby Westminster School to Westminster Cathedral to CCAL, University of the Arts, London (omitting all backstreets nearest to Vauxhall Bridge Road) – derivation: Parliament Square||Westminster|
|SW1V||LONDON||between Vauxhall Bridge, Grosvenor (or Victoria Railway) Bridge and Victoria Station, taking in both sides of Vauxhall Bridge Road; includes Pimlico||Westminster|
|SW1W||LONDON||South or lower Belgravia and Chelsea (a corner), from Sloane Square to Victoria Station to Grosvenor Waterside basin||Westminster, Kensington and Chelsea|
|SW1X||LONDON||Rest of Belgravia (north of Eaton Square), Knightsbridge (eastern half) and Chelsea (a corner)||Westminster, Kensington and Chelsea|
|SW1Y||LONDON||All but the west of St James's||Westminster|
|SW2||LONDON||Brixton district: Brixton Hill, Tulse Hill (part), Brixton (part), Streatham Hill, Clapham Park (part), Lambeth||Lambeth|
|SW3||LONDON||Chelsea district: Chelsea, Brompton, Knightsbridge (part)||Kensington and Chelsea|
|SW4||LONDON||Clapham district: Clapham, Stockwell (part)||Lambeth, Wandsworth|
|SW5||LONDON||Earls Court district: Earl's Court||Kensington and Chelsea|
|SW6||LONDON||Fulham district: Fulham, Parsons Green||Hammersmith and Fulham|
|SW7||LONDON||South Kensington district: South Kensington, Knightsbridge (part)||Kensington and Chelsea, Westminster|
|SW8||LONDON||South Lambeth district: South Lambeth, Vauxhall, Nine Elms (east), Clapham (north), Stockwell (northwest), Oval (west)||Lambeth, Wandsworth|
|SW9||LONDON||Stockwell district: Brixton, Stockwell, Clapham (part), Oval (part)||Lambeth|
|SW10||LONDON||West Brompton district: West Brompton, Chelsea (part)||Kensington and Chelsea, Hammersmith and Fulham|
|SW11||LONDON||Battersea head district: Battersea, Nine Elms (west)||Wandsworth, Lambeth|
|SW12||LONDON||Balham district: Balham, Clapham Park (part), Wandsworth Common (part)||Wandsworth, Lambeth|
|SW13||LONDON||Barnes district: Barnes||Richmond upon Thames|
|SW14||LONDON||Mortlake district: Mortlake, East Sheen||Richmond upon Thames|
|SW15||LONDON||Putney district: Putney, Roehampton, Kingston Vale, Putney Heath, Putney Vale, Richmond Park, Roehampton Vale||Wandsworth, Kingston upon Thames, Richmond upon Thames|
|SW16||LONDON||Streatham district: Streatham, Streatham Common, Norbury, Streatham Park, Furzedown, Streatham Vale, Mitcham Common, Pollards Hill, Eastfields, West Norwood (part)||Lambeth, Croydon, Wandsworth, Merton|
|SW17||LONDON||Tooting district: Tooting, Balham (part), Mitcham (part), Furzedown||Wandsworth, Merton|
|SW18||LONDON||Wandsworth district: Wandsworth Town, Southfields, Earlsfield||Wandsworth|
|SW19||LONDON||Wimbledon district: Wimbledon, Colliers Wood, Merton Park, Merton Abbey, Southfields, Morden (part)||Merton, Wandsworth|
|SW20||LONDON||West Wimbledon district: Raynes Park, Lower Morden, Merton Park, Wimbledon Chase, very small part of the east of New Malden||Merton, Kingston upon Thames|
SW1 is the South Western head district. Since about the 1890s it has had a surplus of addresses and buildings for practical division into one set of inwards codes so is divided into smaller postcode districts since 1917 used for mail purposes. SW1 is used in geographic reference, street signs and colloquial use across most communities. Its eight subdivisions continue to be classed as one 'district'. Within SW1A are keynote inward codes including:
SW19 is the postcode that covers Wimbledon and is used as a synonym for the Wimbledon Championships tennis tournament.  
The SW postcode area covers parts of nine London Boroughs. North of the River Thames, it covers the southern parts of the City of Westminster, the Royal Borough of Kensington and Chelsea and the London Borough of Hammersmith and Fulham. South of the river, it covers all of the London Borough of Wandsworth, the western part of the London Borough of Lambeth, the northern parts of the London Boroughs of Merton and Croydon and the northeastern parts of the London Boroughs of Richmond upon Thames and Kingston upon Thames.  
Postal codes used in the United Kingdom, British Overseas Territories and Crown dependencies are known as postcodes. They are alphanumeric and were adopted nationally between 11 October 1959 and 1974, having been devised by the General Post Office. A full postcode is known as a "postcode unit" and designates an area with several addresses or a single major delivery point.
The London postal district is the area in England of 241 square miles (620 km2) to which mail addressed to the London post town is delivered. The General Post Office under the control of the Postmaster General directed Sir Rowland Hill to devise the area in 1856 and throughout its history it has been subject to reorganisation and division into increasingly smaller postal units, with the early loss of two compass points and a minor retraction in 1866. It was integrated by the Post Office into the national postcode system of the United Kingdom during the early 1970s and corresponds to the E, EC, N, NW, SE, SW, W and WC postcode areas. The postal district has also been known as the London postal area. The County of London was much smaller, at 117 square miles (300 km2), but Greater London is much larger at 607 square miles (1,570 km2).
The W postcode area, also known as the London W postcode area is a group of postcode districts covering part of central and part of West London, England. The area originates from the Western (W1) and Paddington (W2-14) districts of the London postal district. This area covers 35 postcode districts and around 18,554 live postcodes.
The E (Eastern) postcode area, also known as the London E postcode area, is the part of the London post town covering much of east London, England. It borders the N postcode area to the west, both north of the tidal Thames. Since closure of the East London mail centre its mail is sorted at Romford Mail Centre together with IG and RM postcode areas.
The IG postcode area, also known as the Ilford postcode area, is a group of eleven postcode districts in England, within six post towns. These cover parts of eastern Greater London and south-west Essex. Inward mail for the area is sorted, along with mail for the E and RM postcode areas, at the Romford Mail Centre.
The EC postcode area, also known as the London EC postal area, is a group of postcode districts in central London, England. It includes almost all of the City of London and parts of the London boroughs of Islington, Camden, Hackney, Tower Hamlets and Westminster. The area covered is of very high density development. Deliveries for the EC postcode area are made from Mount Pleasant Mail Centre.
The WC postcode area, also known as the London WC postcode area, is a group of postcode districts in central London, England. The area covered is of high density development, and includes parts of the City of Westminster and the London Boroughs of Camden and Islington, plus a very small part of the City of London.
The KT postcode area, also known as the Kingston upon Thames postcode area, is a group of 24 postcode districts in England, within 19 post towns. These cover boroughs in south-west Greater London and several boroughs in north-east Surrey.
The SM postcode area, also known as the Sutton postcode area, is a group of seven postcode districts in England, within five post towns. These cover part of south-west London, as well as a small part of north Surrey.
The TW postcode area, also known as the Twickenham postcode area, is a group of twenty postcode districts in south-east England, within thirteen post towns. These cover parts of south-west London and north-west Surrey, plus a very small part of Berkshire.
The UB postcode area, also known as the Southall postcode area, is a group of eleven postcode districts in England, within six post towns. These cover parts of western and north-western Greater London, plus a very small part of Buckinghamshire. The letters in the postcodes are the phonemic abbreviation of Uxbridge.
The WD postcode area, also known as the Watford postcode area, is a group of eleven postcode districts in Greater London and Hertfordshire, within seven post towns. These cover south-west Hertfordshire, plus very small parts of Buckinghamshire and the London Borough of Hillingdon.
The B postcode area, also known as the Birmingham postcode area, is a group of 79 postcode districts in central England, within 15 post towns. These cover the central portion of the West Midlands, plus northeast Worcestershire, north and west Warwickshire, and part of southeast Staffordshire and a very small part of Leicestershire. It is the most populated postcode area in the United Kingdom, with a population of over 1.9 million.
The NW postcode area, also known as the London NW postcode area, is a group of 13 postcode districts covering around 13,895 live postcodes within part of northwest London, England. It is the successor of the NW sector, originally created as part of the London postal district in 1856.
The RG postcode area, also known as the Reading postcode area, is a group of thirty postcode districts in England, within twelve post towns. These cover west and central Berkshire and north Hampshire, plus a small part of south-east Oxfordshire and very small parts of Buckinghamshire and Wiltshire.
The SE postcode area covers a broad radial swathe of the south-east of the London post town from the Albert Embankment to West Heath and the nearest edges of Sidcup and Selhurst. It loosely corresponds to the boroughs of Southwark, Lewisham and Greenwich plus indicated parts of the boroughs of Croydon (north), Lambeth (east), Bexley (west) and Bromley (northwest).
The NE postcode area, also known as the Newcastle upon Tyne postcode area, is a group of 61 postcode districts in north-east England covering 34 post towns. These cover most of Tyne and Wear and Northumberland, plus a very small part of northern County Durham. The NE postcode area is one of six with a population above 1 million.
The N (Northern) postcode area, also known as the London N postcode area, is the part of the London post town covering part of North London, England. It is a group of 25 postcode districts which covers around 17,429 live postcodes.
The G postcode area, also known as the Glasgow postcode area, is a group of postcode districts in central Scotland, within five post towns. These districts are primarily centered on Glasgow itself, and West Dunbartonshire, plus parts of the council areas of Argyll and Bute, East Dunbartonshire, North Lanarkshire, South Lanarkshire, East Renfrewshire and Stirling.