SO21 postcode district: Colden Common and around, Hampshire
SO21 is a postcode district in Hampshire, with 743 postcodes in use in 3 sectors. It has postcodes in Colden Common, Twyford, Winchester, Eastleigh and 2 more places. It is split between 4 councils: Winchester (692 postcodes), Test Valley (43), Basingstoke and Deane (7) and 1 other.
- Postcodes in use
- 743
- Sectors
- 3
- Councils
- 4 councils
- Places
- 5 places
Source: ONS Postcode Directory, August 2026, loaded 20 October 2026.
Every postcode in SO21, by gigabit broadband
- No home or business can get gigabit: 437
- Some can get gigabit: 119
- Every home and business can get gigabit: 178
- Ofcom gives no figure: 9
- Outline: where 5 or more postcodes without gigabit lie together
Of the 743 postcodes in SO21 that ONS places, 437 have no home or business that can get gigabit, 119 have some that can, 178 can all get it and 9 have no Ofcom figure.
Each mark is a postcode's centre point as ONS gives it, not a building. Press one to see its postcode and open its page. A dashed outline shows where 5 or more lie within 240 metres of each other. It is not a boundary, and no boundary is drawn. Where marks overlap, the one first in the key is drawn; the counts include every postcode.
The middle of its postcodes: latitude 51.0752, longitude -1.3166. Open this area on OpenStreetMap
Sources: ONS Postcode Directory, August 2026, loaded 20 October 2026; Ofcom Connected Nations, Connected Nations, Spring 2026; roads, rivers and built-up areas: Ordnance Survey open maps. Contains OS data © Crown copyright and database right 2026. Drawn by us. Street map: Ordnance Survey, OS Open Zoomstack, Open Government Licence v3.0, drawn with MapLibre.
Postcodes without gigabit
437 postcodes here have no gigabit. These are the 12 first in postcode order.
Where the postcodes without gigabit lie together
- 37 postcodes without gigabit, outlined on the map. SO21 3XX, is the one nearest the middle of them.
- 29 postcodes without gigabit, outlined on the map. SO21 3EA, is the one nearest the middle of them.
- 20 postcodes without gigabit, outlined on the map. SO21 3RG, is the one nearest the middle of them.
- 17 postcodes without gigabit, outlined on the map. SO21 2NS, is the one nearest the middle of them.
- 14 postcodes without gigabit, outlined on the map. SO21 1DJ, is the one nearest the middle of them.
- 13 postcodes without gigabit, outlined on the map. SO21 1EL, is the one nearest the middle of them.
What broadband can you get in SO21?
Ofcom reports on 734 of the 743 postcodes in SO21. At 178 of them every home and business can get gigabit broadband, and at 15 some cannot get decent broadband (10 Mbit/s).
Ofcom gives each postcode's share of homes and businesses, not how many there are, so these count postcodes. Each postcode page has its own figures. A provider's checker answers for one address.
Check one address on Ofcom's checkerSource: Ofcom Connected Nations, Connected Nations, Spring 2026, data for January 2026.
Is SO21 at risk of flooding?
48 of the 743 postcodes in SO21 have a home or business in an area at risk of flooding from rivers or the sea, the Environment Agency says. At those, it puts 77 homes and businesses in an area at high or medium risk.
High: 3.3% or more a year (1 in 30). Medium: 1% to 3.3% a year. Low: 0.1% to 1% a year. Very low: under 0.1% a year (1 in 1,000). Each band is the chance of flooding in any one year.
Homes and businesses in an area at risk of flooding from rivers or the sea, as the Environment Agency counts them, added up over the postcodes. It is for the land, not each building, and leaves out surface water, groundwater and sewers. Each postcode page has its own figures and its flood warning areas.
Source: Environment Agency flood risk, published 6 July 2026.
What do homes sell for in SO21?
Homes in SO21 sold for a typical £529,000 in the 12 months to September 2026, across 196 sales, down 11.8% on the 12 months before, HM Land Registry's figures show.
- Detached £667,500 90 sales
- Semi-detached £450,000 55 sales
- Terraced £398,750 38 sales
- Flat or maisonette £235,000 13 sales
Each bar is that kind's typical price, against the most expensive kind here.
Standard sales of homes at market value. A typical price is the median, the middle sale. Sales take weeks to be registered, so the last month or two are incomplete. Each postcode page gives the figure for its own postcode sector.
Source: HM Land Registry Price Paid Data, files dated 28 October 2026.
Postcodes in SO21
Pick a sector, then a postcode. A sector is the district plus the next digit.
UK postcode format explainedPlaces in SO21
Towns and villages with postcodes in SO21, and how many each has here.
Who covers SO21
How many of the district's postcodes in use fall under each council, constituency and police force area.
Councils
What council am I in?Constituencies
- Winchester692
- Romsey and Southampton North43
- East Hampshire5
- Basingstoke1
- Eastleigh1
- North West Hampshire1
Police force areas
- Hampshire743
Next to SO21
"Next to" is by number: the districts before and after SO21 in the SO area.
Check a postcode
Where the facts on this page come from
- Office for National Statistics: ONS Postcode Directory
- Ofcom Connected Nations
- Environment Agency flood risk
- HM Land Registry Price Paid Data
Contains public sector information licensed under the Open Government Licence v3.0. Contains HM Land Registry data © Crown copyright and database right 2021. This data is licensed under the Open Government Licence v3.0.
Licence: Open Government Licence v3.0.
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