Smart Meter Standards and Accuracy

Smart meters are as accurate as traditional meters when it comes to measuring your electricity or gas usage. That is the official position, stated plainly: the measurement side of a smart meter is not a step down from the spinning disc or dial meter it replaces, and in the great majority of homes it works as intended. As of March 2026, 92% of smart meters work as they should, according to government figures, and every meter installed under the national programme complies with the Smart Meter Equipment Technical Specification, known as SMETS, which sets out how the equipment must be built and behave¹.

What separates a smart meter from an old one is not accuracy but communication. A smart meter is a digital device that records electricity and gas usage in real time and sends those readings to your supplier automatically over a secure national network⁴. That two-way link is what makes accurate billing possible without anyone reading your meter, and it is also where most of the things that go wrong actually go wrong: not in the measuring, but in the sending, the recording and the billing that follows. This page covers how the measurement standards work, how readings become your bill, what to do when they do not, and how a dispute is escalated if your supplier will not fix it.

Measuring up: smart meters against traditional meters

The core claim about accuracy comes from the organisation that runs the national smart meter network. Its guidance is unambiguous:

The same guidance explains that the real difference lies elsewhere: smart meters offer two-way communication, so they can wirelessly send and receive information, which is what allows a supplier to take a reading without visiting your home⁹.

The evidence on how households experience this has improved over time. In the Energy Consumer Satisfaction Survey published in July 2024, satisfaction with smart meters had increased to 72%, up from 68% in the previous wave⁶. The same survey found that the proportion of smart meter users who reported that their in-home display did not match their bill had fallen from 20% in January and February of the earlier wave to 12%⁶. Neither figure is zero, and that gap between what the display shows and what the bill says remains one of the most common triggers for a metering complaint.

The expectation of accurate bills is not new. In a trial reported by Ofgem as far back as June 2007, 27% of participants said getting more accurate fuel bills was a benefit they valued from smart metering, with 21% citing lower bills¹⁰. The promise being made then is the promise the rollout is still judged against now: that billing follows what you actually used, rather than an estimate.

For a household thinking about energy independence, the measurement layer of a smart meter is one of the few parts of the system that genuinely belongs to the home. The meter records usage at source, in half-hour periods, and that record exists whether or not the communications link, the supplier or the app is working. What depends on others is everything that happens to the reading afterwards.

From meter to bill: how readings reach your supplier

A smart meter automatically sends your electricity and gas meter readings to your supplier, which means you get bills based on accurate meter readings and not estimates⁵. The supplier receives those readings over the DCC network, the purpose-built national communications system that links meters to energy companies, and bills you only for the energy you have used¹.

The detail that matters for billing accuracy is the recording interval. Smart meters record energy use in half-hour periods, which enables suppliers to bill on actual rather than estimated usage¹². For electricity, the Welsh Government's guidance describes the updates as nearly real-time¹³. That half-hourly record is also the foundation for anything more sophisticated a household might later want to do with the data, from time-of-use tariffs to sizing a solar and battery system, because it captures when energy is used, not just how much.

The journey from meter to bill runs through several hands, and each one is outside the household:

• The meter records usage in half-hour periods, at source, in your home¹².
• The communications hub carries the readings out of the house over the DCC network¹.
• The supplier's billing systems turn the readings into charges, and bill only for the energy used¹.

The data itself travels wrapped within two layers of encryption before being sent over a dedicated communications system, an approach backed by the National Cyber Security Centre and in line with governance and data protection standards¹⁴. The meter is free to the householder: you contact your supplier to get a smart meter at no cost, and if you have not been offered one you can request it from your supplier⁵.

The dependence to be clear-eyed about is that the reading's journey to your bill runs through infrastructure you do not control: the DCC network, the communications hub on your meter, and your supplier's billing systems. The measurement is local; the billing is not.

Faulty readings and how bills are adjusted

If a smart meter's readings stop reaching the supplier, the fallback is estimation, and an estimated bill is not treated as an accurate one. Under Ofgem's proposed monitoring of billing outcomes, regular energy bills are tested to check that actual meter readings match real consumption and that charges are applied correctly, with statistical sampling possible; crucially, an estimated meter read is not classed as accurate if it differs from actual consumption¹⁷. That gives a household a clear basis for challenge: a bill built on an estimate that does not match the meter is, by the regulator's own definition, not an accurate bill.

The scale of the problem has been substantial. As at March 2023, 3 million smart meters were not working properly, equating to 9% of installed meters, according to the Public Accounts Committee¹⁸. The commonest cause is not the meter itself but the communications link, and the effect is a meter that measures correctly but cannot tell anyone what it has measured. Suppliers are responsible for maintenance and will fix or replace a meter that stops working¹³.

Where a bill has been estimated and later corrected, the supplier recalculates against the actual readings. The householder's protection is that the meter's own record is the authority: the half-hourly data exists at the meter, and a corrected bill should reconcile to it. The page on estimated bills with a smart meter covers the practical steps, and smart meter faults and troubleshooting deals with the common failure modes.

Meters without a signal still record usage accurately

This is the single most reassuring fact for anyone worried about accuracy, and it is worth stating firmly. Ofgem's guidance on smart meter performance says it directly:

Losing communications does not turn the meter into a faulty meter. It turns it back into a traditional one: still counting every kilowatt-hour, but needing someone to read it.

The number of meters in this state has been falling as the network operator works through the backlog of non-communicating meters, but the underlying position for a household is simple. If your meter has gone "dumb", your usage is still being measured, your supplier still has to bill you, and if no readings arrive you may receive estimates until the link is restored or a manual reading is taken. The page on smart meters in dumb mode explains what this looks like in practice.

There is one related category worth knowing about: meters using the Radio Teleswitch Service. If you have an RTS meter, the advice is to contact your supplier to arrange to have a new smart meter installed¹¹, and the RTS switch-off page covers what that means for your heating and hot water.

How the national installation programme affects you

The smart meter rollout has been underway for over 12 years, replacing analogue gas and electricity meters as part of the national infrastructure upgrade to improve and modernise Great Britain's energy system¹². The most recent framework, the Smart Meter Rollout Framework covering 1 January 2022 to 31 December 2025, has now concluded²², and the programme's next deadline is for suppliers to complete the rollout by the end of 2030²⁴.

The programme has not been smooth, and the official verdicts are blunt. The Public Accounts Committee reported in 2023 that the delayed smart meter programme had failed to hit targets and secure public support, noting among other findings that around 3 million, or 9%, of smart meters were not working properly at March 2023¹⁸. The costs have been large: the Data Communications Company's costs were assessed at £4.1 billion, in 2011 prices discounted to 2019, at the 2024 dead-stop²⁵.

For a household, what the rollout means is that the equipment in your home is part of a managed national programme with defined standards, defined supplier obligations and a defined end date, rather than a product you bought and own outright. The meter is installed free⁵, but its long-term behaviour, including whether it keeps communicating, depends on programme decisions taken well above the household.

Communications hubs and the 2G and 3G switch-off

The communications hub is the part of the smart meter set that talks to the outside world, and a large share of them are about to be replaced. An estimated 7 million communications hubs will need to be replaced in the South and Central regions ahead of 2033, when the 2G and 3G communications networks are closed¹⁹. The Public Accounts Committee put the same figure at an estimated seven million hubs, part of the electricity smart meters, which will lose functionality when the 2G and 3G mobile networks close¹⁸.

The behaviour during the transition is defined. On the 3G switch-off, the network operator's guidance states that "Your smart meter will continue to operate as normal following the 3G switch-off, as smart meters will switch seamlessly to the 2G network"²⁶. The harder deadline is 2G's own closure: second-generation smart meters that rely on 2G and 3G will require a replacement Communications Hub in order to communicate with 4G networks²⁶, and suppliers are required to replace all smart meters still connected to 2G and 3G before the services are switched off by 2033². The costs of the 2G/3G to 4G transition are treated separately from the original rollout in the programme's cost-benefit accounting, with benefits for 2034 reduced to reflect the switch-off²⁵.

Second-generation meters, known as SMETS2, were designed to connect directly to the DCC's secure national network, which allows you to switch supplier while retaining smart functionality²⁷. Cross-compatibility means a smart meter keeps its smart functions across all energy suppliers⁹, and SMETS2 meters are now the type used for any new installation. The SMETS1 and SMETS2 page explains the generations, and smart meter communications covers how the networks fit together.

Suspecting your meter is faulty

The first step is your supplier, and the rules on what happens next are set out in the official guidance on your rights and expectations. If you suspect an issue with your smart meter, or your supplier identifies one, the supplier should promptly investigate, resolve the issue themselves or with third parties, and keep you informed¹². The supplier is responsible for the meter's maintenance and will fix or replace it as needed¹³.

It is worth separating two different complaints before you pick up the phone:

• The meter is measuring wrongly. This is rare, and is resolved by investigation and, if necessary, replacement¹².
• The meter is measuring correctly but the bill does not reflect it. This is the far more common case, and usually traces back to a lost communications link, an estimated bill or a billing system error¹⁷.

The evidence you bring matters: the meter's own readings, your in-home display figures and any bills that look wrong. The Energy Ombudsman expects a complainant to have sufficient evidence to support their case, including the date the complaint was raised with the supplier²⁸.

If the issue is not resolved to your satisfaction, you can complain to the Energy Ombudsman¹². Before that point, the practical steps are on the smart meter not sending readings page, and the question of whether you can decline a meter at all is covered under are smart meters compulsory: it is your right to refuse installation, though replacement options may be limited if a traditional meter is faulty or unsafe⁹.

Supplier duties and guaranteed service levels

Suppliers' obligations on smart meters are being tightened into enforceable standards. Ofgem's final decision on smart meter Guaranteed Standards of Performance, published in January 2026, sets out what a supplier must do when a metering problem is raised. Under the standard covering investigation of smart meter operational issues, the energy supplier must complete an initial assessment, take appropriate action and offer to update the consumer, within 5 working days²¹.

The standards apply to SMETS meters specifically. During consultation, respondents noted that the legal drafting referenced the Electricity and Gas Acts, which could inadvertently include advanced metering, and asked for the definition to be clarified so the standards apply only to SMETS meters²¹. The government's guide, Smart Meters: Your Rights and Expectations, sets out the standards energy suppliers should follow at each stage of the customer's smart meter journey²⁹.

The pressure behind these standards comes from complaint volumes. Ofgem's draft impact assessment of August 2025 reported that smart meters had become the leading cause of consumer complaints, at 30% of complaints made to suppliers, up from 29%, when they were the second most common reason³⁰. Automatic compensation is also on the table: Ofgem consulted on arrangements that would see automatic compensation for smart metering consumers where their energy supplier fails to meet certain expectations¹². Reforms already brought forward by Ofgem introduced £40 compensation for failures such as delayed or failed installations², and the redress associated with the smart meter standards is estimated at £117m for GB consumers and suppliers³⁰. The detail is on the smart meter guaranteed standards page.

Taking complaints to the Energy Ombudsman

If a supplier cannot or will not resolve a metering or billing complaint, the Energy Ombudsman is the next step, and its service is free to consumers³¹. The volume of smart meter cases it handles is rising: the Ombudsman received 4,555 smart meter complaints in the first half of 2025 and 4,817 in the first half of 2026, a rise of 6%⁷.

The route from an unresolved complaint to a decision runs in a fixed order:

1. Raise the complaint with your supplier and note the date, because the timeline for escalation runs from it²⁸.
2. Wait, or receive a deadlock letter. You can bring a dispute once at least 8 weeks have passed since you first raised the issue, or sooner if the supplier sends a deadlock letter confirming its complaints process has ended³².
3. Register with the Ombudsman by searching for your energy supplier's name³³. You have up to 14 days to upload evidence³¹, and if you have a deadlock letter you must escalate within 12 months of receiving it³¹.
4. Receive a decision. On average most disputes are resolved within 6 weeks of the Ombudsman receiving evidence from both parties⁸.
5. Implementation. If you accept the resolution, your supplier is obliged to implement it within 28 days³¹.

Financial awards are based on the cost of putting things right, such as ensuring you have been charged accurately, clearing unfair charges or fixing faults⁸. The maximum is up to £10,000 for domestic energy disputes, or up to £20,000 for small business disputes, though the level may vary depending on the type of energy company and the Terms of Reference covering that scheme⁸. In practice, the most common financial award is around £50, sometimes referred to as a Time and Trouble Award³¹. The Ombudsman is funded by the suppliers signed up to the scheme, which pay a fee for each case reviewed regardless of the outcome³¹.

How to make contact. For energy complaints, call 0330 440 1624³¹; some of the Ombudsman's own pages also list 0845 055 0760, so the two published numbers differ³⁴. Phone lines are open Monday to Friday, 8am until 6pm, closed Saturday, Sunday and bank holidays³⁴. The postal address is Energy Ombudsman, P.O. Box 966, Warrington, WA4 9DF³⁴. The Ombudsman only handles disputes involving suppliers trading in Britain³¹, and it covers energy suppliers, energy brokers, network operators, Green Deal providers and, since 1 April 2025, heat network suppliers³⁵.

Accuracy and homes that generate their own power

For a household working towards energy independence, the smart meter's measurement layer is trustworthy and local: it records your usage in half-hour periods, accurately, whether or not anything downstream is working. That record is the raw material for everything else on this site, from using energy data to size a system to joining time-of-use tariffs and flexibility schemes. A home that knows exactly what it uses, and when, is a home that can plan solar, battery and heating decisions on evidence rather than guesswork.

The dependence sits above the meter. The reading travels on a network you do not own, through a hub that will be replaced on a national timetable, to a supplier whose billing systems you cannot inspect, under standards enforced by a regulator and an ombudsman rather than by you. None of that undermines the measurement, but it explains why a metering complaint is resolved by escalation rather than by anything a householder can do at the meter itself. The accurate data is yours; the system that turns it into a bill is not.