TL;DR
- The Ofcom Checker (checker.ofcom.org.uk) provides the only standardised, operator-neutral 5G coverage map for the UK and is the most useful independent reference.
- Operator coverage maps show predicted outdoor signal only; indoor coverage is separately indicated on most maps but is typically less reliable.
- Coverage maps are modelled predictions, not live measurements—real-world performance at any given point may differ, particularly inside buildings or in terrain with complex geography.
- A 5G indicator on your handset does not guarantee fast speeds; a congested cell or weak signal can produce 5G-labelled connections with 4G-level or lower throughput.
- The Shared Rural Network (SRN) programme is expanding coverage in rural areas, meaning maps are updated periodically and a check from a year ago may be outdated.
Why Coverage Checkers Matter and What They Actually Measure
Coverage maps are predictive models, not real-time measurements of signal strength. Operators and Ofcom generate them by combining information about mast locations, antenna orientations and power levels, terrain data, and propagation models for each frequency band. The result is a grid-based prediction of whether a device at a given point is likely to receive a usable signal. This is a fundamentally different thing from measuring the speed or quality of the connection a user will experience—a point that is important to understand before relying on any checker to make decisions about a contract or a house purchase.
Ofcom requires operators to submit coverage data annually as part of the Connected Nations reporting process. This data underpins the Ofcom Checker tool, which aggregates predictions from all four major UK mobile network operators (MNOs). The methodology is standardised, meaning results from different operators are calculated on a comparable basis—something that is not true when comparing operator-published maps directly against one another, since each uses its own modelling assumptions.
The Ofcom Checker: What It Shows and How to Use It
Ofcom’s Checker (accessible at checker.ofcom.org.uk) allows users to enter a postcode or address and see predicted coverage for each of the four main UK MNOs across 2G, 3G, 4G, and 5G. Results are shown as a traffic-light style indicator distinguishing between outdoor coverage (signal predicted at street level) and indoor coverage (signal predicted to penetrate into a typical building). The 5G layer shows where an operator predicts 5G NR service to be available, though it does not distinguish between frequency bands or indicate expected speeds.
The checker is most useful as a first step when evaluating which operators offer 5G in a specific area before signing a contract. It is also the appropriate tool when making a formal complaint about coverage to Ofcom or an operator, as it provides an independent reference. Users should note that results reflect predicted outdoor coverage at the postcode centroid, not the precise coordinates of a building, and that indoor predictions carry greater uncertainty than outdoor ones. Checking multiple nearby postcodes can give a better sense of signal variability in a localised area.
Operator Coverage Checkers: Uses and Limitations
Each of the four main UK MNOs—EE, O2, Three, and Vodafone—publishes its own coverage map on its website. These maps typically offer higher visual resolution than the Ofcom Checker and may be updated more frequently, particularly following new site activations. Some operator maps allow users to filter by service type (voice, 4G data, 5G) and to view separate outdoor and indoor layers. They can be useful for checking the specific operator you are on or considering, and for identifying the boundaries of 5G coverage in a neighbourhood.
The limitation is that operator maps are produced using that operator’s own methodology and may present coverage in a more favourable light than an independent model would. Ofcom’s standardised approach applies consistent assumptions about signal thresholds and building penetration loss; an operator may use more optimistic assumptions in its own map. Additionally, operator maps are not always transparent about the spectrum band being modelled—a cell site carrying both 3.5 GHz and 700 MHz 5G may show broader coverage than is delivered by the higher-frequency band alone, which is the one relevant to peak speed expectations.
| Checker | Operator Neutral? | Indoor Coverage Shown? | Update Frequency | Best Use |
|---|---|---|---|---|
| Ofcom Checker (checker.ofcom.org.uk) | Yes – all 4 MNOs | Yes (separate indicator) | Annually (Connected Nations) | Independent comparison, complaints reference |
| EE Coverage Checker | EE only | Yes | More frequent (operator-managed) | Detailed EE 5G boundary mapping |
| O2 Coverage Checker | O2 only | Yes | More frequent (operator-managed) | O2-specific pre-contract check |
| Three Coverage Checker | Three only | Yes | More frequent (operator-managed) | Three-specific pre-contract check |
| Vodafone Coverage Checker | Vodafone only | Yes | More frequent (operator-managed) | Vodafone-specific pre-contract check |
Reading Coverage Map Colour Coding
UK coverage maps typically use a tiered colour scheme to indicate signal levels, though exact colours vary by provider. Green or dark shading generally indicates strong outdoor coverage; lighter shading or hatching typically represents predicted indoor coverage; and white or unshaded areas indicate no predicted coverage. Some operator maps add a further tier for 5G availability on top of a 4G base layer, requiring users to toggle between views to understand what type of service is predicted at a given location.
The distinction between outdoor and indoor predictions is the most practically important colour-coding distinction. Ofcom’s indoor prediction assumes a signal loss of around 10–20 dB to account for typical building materials, reflecting the attenuation that 5G frequencies (especially 3.5 GHz) experience when passing through walls and windows. A location shown as having outdoor 5G coverage but no indoor 5G coverage indicates that the operator’s model predicts the signal will degrade below a usable threshold when entering a building—which is a common situation for 5G in the UK, particularly at the periphery of coverage zones.
The Shared Rural Network and How It Affects Map Accuracy
The Shared Rural Network (SRN) is a government and industry programme designed to extend 4G (and eventually 5G) to rural areas of the UK that previously had partial or no coverage. Under the SRN, operators may share infrastructure to deliver coverage they would not build individually. As new sites come online under the SRN, both Ofcom and operator maps are updated to reflect the expanded footprint, meaning a coverage check conducted a year or more ago may no longer reflect the current situation in rural areas.
For users in rural or semi-rural locations, it is worth re-checking coverage maps periodically rather than relying on a historic check. Ofcom publishes progress data on SRN deployment through its Connected Nations updates, which can help identify whether coverage in a given region has recently improved. Users in areas that gain coverage through the SRN will initially be on a shared infrastructure site, which may have different capacity characteristics than a dedicated operator cell.
What This Means in Practice
Marcus is considering switching to a new 5G plan and wants to know if he will receive 5G at his flat in Sheffield city centre. He checks the Ofcom Checker first, which shows outdoor 5G coverage from two of the four operators at his postcode, with one operator also predicting indoor coverage. He then checks that operator’s own map, which confirms 5G at his address for both outdoor and indoor use. Satisfied that the independent and operator sources agree, he proceeds with that network. During the first week of use, he notices his phone shows 5G in his living room but achieves only around 40 Mbps—consistent with marginal indoor coverage where the signal is just above the usable threshold. The coverage map correctly predicted 5G was available; it could not predict the speed he would receive at signal levels near the indoor coverage boundary.
Related Guides
How We Verified This
This article draws on Ofcom’s Connected Nations reports and the methodology documentation for the Ofcom Checker (checker.ofcom.org.uk); Ofcom’s Shared Rural Network progress updates; Ofcom’s guidance on coverage obligations attached to spectrum licences; and GOV.UK documentation on the SRN programme and coverage commitments made by the four main MNOs.
Disclaimer: Kaeltripton.com is an independent UK editorial publisher. We are not regulated by Ofcom or the FCA and we do not sell or arrange mobile services, insurance, or financial products. This content is for general information only and is not legal, financial, or technical advice. Rules, prices, and operator policies change. Verify the current position with Ofcom, GOV.UK, the ICO, or your provider before acting. ICO registered ZC135439. Last reviewed: 2026-06-05.
Frequently Asked Questions
Which 5G coverage checker should I use?
Start with the Ofcom Checker at checker.ofcom.org.uk, which provides a standardised, operator-neutral view of predicted 5G coverage from all four main UK MNOs at a single postcode. Then cross-reference with the specific operator’s own map for the network you are considering, as operator maps may be updated more frequently and offer finer geographic detail. Using both together gives the most complete picture before committing to a contract.
How accurate are 5G coverage maps?
Coverage maps are predictive models based on mast locations, antenna data, and propagation algorithms—they are not real-time measurements of signal quality. Outdoor predictions are generally more reliable than indoor ones. Factors such as local terrain, new buildings, trees, and even weather conditions can cause actual reception to differ from the prediction. Treat coverage maps as a guide rather than a guarantee, particularly for indoor or fringe coverage assessments.
Why does my phone show 5G but speeds are slow?
A 5G indicator on a handset confirms only that the device has registered onto the 5G NR network—it does not indicate signal strength or available throughput. A congested 5G cell, a weak signal at the edge of coverage, or a connection on a lower-frequency 5G band (such as 700 MHz) may all display the 5G icon while delivering speeds comparable to 4G. Checking signal bars alongside the network indicator gives a better sense of likely performance.
What is the difference between indoor and outdoor 5G coverage?
Outdoor coverage predictions assume the device is at street level with no building obstruction. Indoor predictions apply an additional signal-loss factor (typically 10–20 dB) to account for attenuation through building materials. Because 5G’s primary band (3.5 GHz) penetrates buildings less effectively than the lower-frequency bands used for 4G, a location can have good outdoor 5G coverage while showing no predicted indoor 5G coverage on the same map, which is a common situation across UK cities.
How do I check if 5G is available at my home?
Enter your home postcode into the Ofcom Checker at checker.ofcom.org.uk and select the 5G layer. Check both outdoor and indoor predictions for each operator. Then verify against the specific operator’s own checker for the most current data. If both the Ofcom Checker and the operator’s map show indoor 5G at your postcode, there is a reasonable expectation of 5G indoors, though actual performance depends on building construction and the specific location within the property.
