SG4 postcode district: Hitchin and around, Hertfordshire

SG4 is a postcode district in Hertfordshire, with 906 postcodes in use in 4 sectors. It has postcodes in Hitchin, Codicote and Stevenage. It is split between 3 councils: North Hertfordshire (900 postcodes), Stevenage (5) and Welwyn Hatfield (1).

Postcodes in use: 906
Sectors: 4
Councils: 3 councils
Places: 3 places

Source: Office for National Statistics (ONS) Postcode Directory, August 2026, loaded 20 October 2026. See all our data sources

Every postcode in SG4, and which are new since 2020

New since 2020: 36
In use before 2020: 870
Outline: where 5 or more new postcodes since 2020 lie together

Of the 906 postcodes in SG4 that ONS places, 36 are new since 2020 and 870 were in use before 2020.

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. New since 2020 means it came into use in January 2020 or later. A dashed outline shows where 5 or more lie within 180 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 51.9195, longitude -0.2594. Open this area on OpenStreetMap

Source: Office for National Statistics (ONS) Postcode Directory, August 2026, loaded 20 October 2026, the centre point of each postcode; when each came into use: the same directory; roads, rivers and built-up areas: 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. How we use them

The 5 newest postcodes

SG4 8FNJuly 2026 SG4 8DWDecember 2025 SG4 8EZSeptember 2025 SG4 8FGSeptember 2025 SG4 8DYJuly 2025

Where the new postcodes lie together

9 new postcodes since 2020, outlined on the map. SG4 8DW, is the newest of them.

What broadband can you get in SG4?

Ofcom reports on 894 of the 906 postcodes in SG4. At 536 of them every home and business can get gigabit broadband, and at 15 some cannot get decent broadband (10 Mbit/s).

Postcodes where every home can get gigabit536 of 894

Postcodes where every home can get superfast788 of 894

Postcodes where some cannot get decent broadband15 of 894

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 checker

Source: Ofcom, Connected Nations, Spring 2026, data for January 2026, Open Government Licence v3.0. How we use it

Is SG4 at risk of flooding?

59 of the 906 postcodes in SG4 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 207 homes and businesses in an area at high or medium risk.

Homes and businesses in an area at risk, at 59 of 906 postcodes High: 98Medium: 109Low: 255

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, Risk of Flooding from Rivers and Sea (postcodes in areas at risk), published 6 July 2026, Open Government Licence v3.0. How we use it

What do homes sell for in SG4?

Homes in SG4 sold for a typical £475,000 in the 12 months to August 2026, across 388 sales, down 6.4% on the 12 months before, HM Land Registry's figures show.

£475,000 typical price, the 12 months to August 2026

£507,500 12 months to August 2025

▼ down 6.4% on the 12 months before

Detached £830,000 86 sales
Semi-detached £532,000 117 sales
Terraced £400,000 95 sales
Flat or maisonette £251,100 90 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 September 2026. Contains HM Land Registry data © Crown copyright and database right 2021. This data is licensed under the Open Government Licence v3.0. How we use it