Q1
Best network for CM9?
O2 leads with 100/100 — driven by 100% 5G and 100% 4G in this mixed urban-rural part of Chelmsford.
CM9 DISTRICT · BRAINTREE
Best mobile network in Maldon CM9 · Braintree
O2 scores 100/100 — the best measured network for CM9 in Chelmsford, 8 points clear of the weakest. 100% 5G-grade · 100% 4G. Ofcom Mobile Coverage data (May 2025), measured across 103 addresses in 5 sampled postcodes.
The CM9 district covers Maldon, Heybridge, Purleigh and Tollesbury, in Braintree. Signal varies street by street — scan your exact postcode below.
RESULT · CM9 · CHELMSFORD
Coverage for CM9 district
★ BEST MEASURED
O2
100/100
O2 has the strongest measured coverage for the CM9 district in Chelmsford, 8 points clear of the weakest network in Ofcom's data.
Full ranking — CM9
#1
O2
#2
Vodafone
#3
EE
#4
Three
Coverage analysis — CM9
According to Ofcom's Mobile Coverage data, O2 outperforms rivals in Chelmsford. In this mixed urban-rural area, O2 achieves an overall coverage score of 100/100 — driven by excellent 5G coverage (100%) and rock-solid 4G at 100%. 5G and 4G scores are closely matched, reflecting a mature, stable network.
O2 consistently leads Vodafone by 0 points overall. While Vodafone reaches 100% on 5G and 100% on 4G in Chelmsford, it falls short of O2's combined performance across all bands. EE and Three round out the field at 97 and 92 respectively.
Why O2 for CM9?
O2's 5G rollout in Chelmsford is among the strongest nationally, covering 100% of premises in the CM9 district. For anyone streaming video, gaming on mobile, or relying on a mobile hotspot at home, this level of 5G penetration makes a real difference to day-to-day speed.
The runner-up in CM9 is Vodafone at 100/100 (100% 5G / 100% 4G). It is a close contest — both operators deliver strong coverage in CM9, and your choice may come down to tariff, handset preference, or existing contract.
Switching to O2 in Maldon
O2 has the strongest measured signal here — 100/100, with 100% 5G-grade and 100% 4G coverage across Maldon, Heybridge, Purleigh and Tollesbury, 8 points clear of the weakest. A cheaper plan on a network that does not reach your street costs more than it saves, so start from the coverage and pick the plan second.
Some links on this page are affiliate links. If you switch through one we may be paid a commission. It never changes which network we rank first - that comes from Ofcom coverage data alone.
Explore the Chelmsford area
View full coverage analysis for the Chelmsford (CM) area, or enter any UK postcode in the scanner above for a personalised result.
Coverage FAQ — CM9
Q2
Is 5G available in CM9?
O2 provides excellent 5G coverage at 100%. Vodafone follows at 100%.
Q3
Which network has the best 4G?
O2 leads 4G too at 100%. Reliable 4G is critical in mixed urban-rural areas.
Q4
Is EE worth considering?
EE scores 97/100 in CM9 (100% 5G, 100% 4G). It may suit certain tariff or price preferences despite trailing the top two.