SL4 postcode district: Windsor and around
SL4 is a postcode district in England, with 1,376 postcodes in use in 7 sectors. It has postcodes in Windsor, Old Windsor and Wraysbury, Eton and 1 more place. It is split between 5 councils: Windsor and Maidenhead (1,255 postcodes), Bracknell Forest (97), Buckinghamshire (20) and 2 others. 2 of its 1,376 postcodes are in Surrey. ONS lists no county for the other 1,374.
- Postcodes in use
- 1,376
- Sectors
- 7
- Councils
- 5 councils
- Places
- 4 places
Source: ONS Postcode Directory, August 2026, loaded 20 October 2026.
Every postcode in SL4, by gigabit broadband
- No home or business can get gigabit: 227
- Some can get gigabit: 204
- Every home and business can get gigabit: 853
- Ofcom gives no figure: 92
- Outline: where 5 or more postcodes without gigabit lie together
Of the 1,376 postcodes in SL4 that ONS places, 227 have no home or business that can get gigabit, 204 have some that can, 853 can all get it and 92 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 150 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 51.4753, longitude -0.6276. 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
227 postcodes here have no gigabit. These are the 12 first in postcode order.
Where the postcodes without gigabit lie together
What broadband can you get in SL4?
Ofcom reports on 1,284 of the 1,376 postcodes in SL4. At 853 of them every home and business can get gigabit broadband, and at 4 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 SL4 at risk of flooding?
571 of the 1,376 postcodes in SL4 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 1,299 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 SL4?
Homes in SL4 sold for a typical £500,000 in the 12 months to September 2026, across 387 sales, HM Land Registry's figures show. The 12 months before gave £520,000 from 592 sales: not a change larger than chance would explain, given which homes happened to sell.
- Detached £805,000 67 sales
- Semi-detached £574,000 98 sales
- Terraced £495,000 123 sales
- Flat or maisonette £305,000 99 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 SL4
Pick a sector, then a postcode. A sector is the district plus the next digit.
Places in SL4
Towns and villages with postcodes in SL4, and how many each has here.
Who covers SL4
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
- Windsor1,230
- Maidenhead124
- Beaconsfield20
- Slough2
Police force areas
- Thames Valley1,374
- Surrey2
Next to SL4
"Next to" is by number: the districts before and after SL4 in the SL 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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