Q1
Best network for PO18?
Three leads with 99/100 — driven by 100% 5G and 100% 4G in this densely populated urban part of Portsmouth.
PO18 DISTRICT · ARUN
Best mobile network in Dean PO18 · Arun
Three scores 99/100 — the best measured network for PO18 in Portsmouth, 7 points clear of the weakest. 100% 5G-grade · 100% 4G. Ofcom Mobile Coverage data (May 2025), measured across 47 addresses in 5 sampled postcodes.
The PO18 district covers Dean, Chichester, Lavant and Harting, in Arun. Signal varies street by street — scan your exact postcode below.
RESULT · PO18 · PORTSMOUTH
Coverage for PO18 district
★ BEST MEASURED
Three
99/100
Three has the strongest measured coverage for the PO18 district in Portsmouth, 7 points clear of the weakest network in Ofcom's data.
Full ranking — PO18
#1
Three
#2
O2
#3
Vodafone
#4
EE
Coverage analysis — PO18
According to Ofcom's Mobile Coverage data, Three scores highest across Portsmouth. In this densely populated urban area, Three achieves an overall coverage score of 99/100 — driven by excellent 5G coverage (100%) and rock-solid 4G at 100%. 5G and 4G scores are closely matched, reflecting a mature, stable network.
Three comfortably leads O2 by 2 points overall. While O2 reaches 100% on 5G and 100% on 4G in Portsmouth, it falls short of Three's combined performance across all bands. Vodafone and EE round out the field at 96 and 92 respectively.
Why Three for PO18?
Three's 5G rollout in Portsmouth is among the strongest nationally, covering 100% of premises in the PO18 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 PO18 is O2 at 97/100 (100% 5G / 100% 4G). It is a close contest — both operators deliver strong coverage in PO18, and your choice may come down to tariff, handset preference, or existing contract.
Switching to Three in Dean
Three has the strongest measured signal here — 99/100, with 100% 5G-grade and 100% 4G coverage across Dean, Chichester, Lavant and Harting, 7 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 Portsmouth area
View full coverage analysis for the Portsmouth (PO) area, or enter any UK postcode in the scanner above for a personalised result.
Coverage FAQ — PO18
Q2
Is 5G available in PO18?
Three provides excellent 5G coverage at 100%. O2 follows at 100%.
Q3
Which network has the best 4G?
Three leads 4G too at 100%. Reliable 4G is critical in densely populated urban areas.
Q4
Is Vodafone worth considering?
Vodafone scores 96/100 in PO18 (100% 5G, 100% 4G). It may suit certain tariff or price preferences despite trailing the top two.