CM POSTCODE AREA · 9 DISTRICTS SAMPLED
Chelmsford mobile coverage O2 strongest indoors, 98% vs Three 83% CM postcode area
No network wins Chelmsford on overall coverage: all four are within 3 points, but indoors O2 reaches 98% of sampled addresses and Three 83%.
Chelmsford as a whole
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EE
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O2
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Vodafone
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Three
Ofcom Mobile Coverage data (May 2025), measured across 1,206 addresses in 51 sampled postcodes, pooled from 9 districts. Methodology.
What differs inside Chelmsford
Where the networks split most
- CM9 Maldon, Heybridge, Purleigh: indoors O2 and Vodafone 100%, Three 50%.
- CM6 Great Dunmow, Felsted, Takeley: indoors O2 100%, Three 57%.
- CM3 Hanningfield, Sandon, Boreham: indoors EE and Three 100%, Vodafone 63%.
Each network's weakest and strongest district
| Network | Indoor |
|---|---|
| EE | 82% in CM9 Maldon; 100% in 6 districts |
| Three | 50% in CM9 Maldon; 100% in 5 districts |
| Vodafone | 63% in CM3 Hanningfield; 100% in 5 districts |
Middle of the area against its edges
The 3 districts nearest the middle (CM1 Writtle, CM2 Great Baddow, CM3 Hanningfield) against the 3 furthest out (CM5 Ongar, CM6 Great Dunmow, CM7 Braintree):
- Three indoors: 100% in the middle, 72% at the edges.
District by district
| District | Places | Indoor, low to high | Addresses |
|---|---|---|---|
| CM1 | Writtle, Broomfield, High Easter | 100% on all four | 96 |
| CM2 | Great Baddow, Sandon, Boreham | 100% on all four | 175 |
| CM3 | Hanningfield, Sandon, Boreham | Vodafone 63%; EE and Three 100% | 94 |
| CM4 | Billericay, Margaretting, Mountnessing | 100% on all four | 88 |
| CM5 | Ongar, Fyfield, Moreton | Three 80%; EE 100% | 188 |
| CM6 | Great Dunmow, Felsted, Takeley | Three 57%; O2 100% | 178 |
| CM7 | Braintree, Bocking, Thaxted | Three 77%; EE and O2 94% | 193 |
| CM8 | Witham, Cressing, Silver End | 100% on all four | 91 |
| CM9 | Maldon, Heybridge, Purleigh | Three 50%; O2 and Vodafone 100% | 103 |
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1pMobile runs on EE's network: £5 a month for 5GB (read 19 October 2026). A price, not a coverage ranking: Ofcom separates no network here.
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