CM20 postcode district: Harlow and around

CM20 is a postcode district mostly in Essex, with 629 postcodes in use in 4 sectors. It has postcodes in Harlow. It is split between 2 councils: Harlow (597 postcodes) and East Hertfordshire (32). 597 are in Essex and 32 in Hertfordshire.

Postcodes in use: 629
Sectors: 4
Councils: 2 councils
Places: Harlow

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

Every postcode in CM20, and which are new since 2020

New since 2020: 57
In use before 2020: 572
Outline: where 5 or more new postcodes since 2020 lie together

Of the 629 postcodes in CM20 that ONS places, 57 are new since 2020 and 572 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 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 51.7757, longitude 0.1028. 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

CM20 2UPJuly 2026 CM20 9XSJune 2026 CM20 9XTJune 2026 CM20 3FFMarch 2026 CM20 3FGFebruary 2026

3 further out, not drawn

These postcodes lie well apart from the rest, so the map is drawn without them to show the rest closer; they are in every count.

CM20 2RA CM20 3SD CM20 9SB

Where the new postcodes lie together

38 new postcodes since 2020, outlined on the map. CM20 9XS, is the newest of them.
6 new postcodes since 2020, outlined on the map. CM20 2UH, is the newest of them.

What broadband can you get in CM20?

Ofcom reports on 546 of the 629 postcodes in CM20. At 310 of them every home and business can get gigabit broadband, and at 1 some cannot get decent broadband (10 Mbit/s).

Postcodes where every home can get gigabit310 of 546

Postcodes where every home can get superfast457 of 546

Postcodes where some cannot get decent broadband1 of 546

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 CM20 at risk of flooding?

23 of the 629 postcodes in CM20 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 124 homes and businesses in an area at high or medium risk.

Homes and businesses in an area at risk, at 23 of 629 postcodes High: 34Medium: 90Low: 170Very low: 2

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 CM20?

Homes in CM20 sold for a typical £325,000 in the 12 months to August 2026, across 195 sales, up 4.8% on the 12 months before, HM Land Registry's figures show.

£325,000 typical price, the 12 months to August 2026

£310,000 12 months to August 2025

▲ up 4.8% on the 12 months before

Detached £636,000 10 sales
Semi-detached £400,000 15 sales
Terraced £335,000 99 sales
Flat or maisonette £202,000 71 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