How Does a Smart Meter Work?

A smart meter measures gas and electricity use and sends the readings straight to the energy supplier, with no one having to read the meter at the door or type numbers into a website¹. It does this over a secure national network built only for smart meters, not over home Wi-Fi, and it comes with a portable touchscreen display that shows how much energy the home is using in near real time².

The data a smart meter produces is used to bill the household for the energy it actually uses, to offer new products and services such as new tariffs where permission has been given, and to help make the energy system more efficient by recording demand more accurately². What it does not do is control anything in the home: it measures, reports and, in prepayment mode, holds credit. It cannot switch appliances on or off, and it records nothing about the household's life beyond the flow of gas and electricity through the meter.

How smart meters work

A smart meter is a replacement for the traditional gas and electricity meters in a home. It measures usage and sends the data directly to the energy supplier¹. Where an old meter simply accumulated a total that someone had to read, a smart meter communicates in two directions: it can wirelessly send information out and receive instructions back, which is what allows remote readings, remote switching between credit and prepayment modes, and over-the-air top-ups⁹.

The data the supplier receives is used for three things: to bill the household for the energy it uses, to offer new products and services such as new tariffs if permission has been given for that, and to help make the wider energy system more efficient by recording demand more accurately². Because energy use is recorded automatically in half-hour periods, suppliers can bill on actual rather than estimated usage¹⁰.

It is worth being clear about what the meter does not do:

• It does not control heating, appliances or anything else in the house.
• It cannot switch off the supply remotely in normal circumstances.
• It does not spy on activities: it records only how much energy flows through it.
• The savings it can bring come from what the household does with the information, not from the meter acting on its behalf.

The parts: the meter, the display and the network link

Smart meters have two parts in the home: the meter itself, which replaces the old meter, and a display screen that shows how much gas and electricity is being used and what it costs⁴. The meter is installed where the old meter was; the display is a portable touchscreen device that can be placed wherever it is useful, usually the kitchen¹¹.

The display is not the meter. It is a window onto the meter's readings, sent to it wirelessly over a short-range link within the home. Readings are transmitted automatically to the in-home display and to the energy supplier using the national smart energy network¹². So the system has three layers: the meter that measures, the display that shows the result, and the network that carries the data onward to the supplier. The display depends on the meter; the meter does not depend on the display.

How readings travel: the secure national network, not your Wi-Fi

The single most common misunderstanding about smart meters is that they connect to the internet through the household's broadband. They do not. A smart meter does not use home Wi-Fi, does not connect to the router and does not affect broadband speed¹³. No home Wi-Fi, broadband, router or internet package is needed for a smart meter to send readings¹³.

Instead, readings travel over a secure smart data network solely for smart meters, which does not use the internet¹⁴. This is the network operated by the Data Communications Company (DCC), and sending a meter reading requires no internet connection because smart meters work using the DCC's secure, standalone network¹⁵. From the home, readings are transmitted to a wide area network made up of mobile phone or radio masts, and the most used message on that network is the meter read itself, allowing suppliers to read usage remotely⁷.

The network uses two layers of encryption and operates entirely separately from the public internet¹⁶. Data is wrapped within those 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 standards¹⁵. Through this network, smart meter data can also be shared securely between authorised users, supporting smart energy services across the sector¹¹.

The in-home display: what it shows

Every smart meter installation comes with an in-home display, a portable touchscreen device that shows near real-time energy usage data¹¹. It shows how much energy the home is using during the day, so the jump is visible when the kettle goes on or the oven heats up³. Suppliers provide the display so consumers can see and manage their energy use¹⁰.

The display is the part of the system the household actually lives with. The meter sits in a cupboard or box; the display sits on a worktop and answers the everyday questions: how much is being used now, and what is it costing. It updates as use changes, which is what makes it useful for spotting what drives the bills in a way a quarterly statement never can.

The display has two modes, depending on how the energy is paid for⁹. In credit mode it shows use and cost against a bill that arrives later; in prepayment mode it shows remaining credit and warns when it is running low. Both are covered below.

Credit mode and prepay mode

Smart meters can operate in credit or prepayment mode¹⁰, and they work for both credit and prepay customers⁴. In credit mode the household pays for energy after using it, billed on the readings the meter sends. In prepayment mode payment comes first, and the meter holds credit like a pay-as-you-go phone.

In prepayment mode, a smart meter lets the household add credit automatically or without having to visit a shop². A smart prepayment meter can be topped up online or using the supplier's mobile app¹⁷, and the prepayment service on the national network carries that credit to the meter as an over-the-air top-up⁷. This removes the old routine of queuing at a shop with a key or card, and it means emergency credit can be applied remotely.

The same meter can generally be moved between modes, which is one of the practical advantages over traditional prepayment meters: switching from prepayment to credit, or back, is a remote operation rather than a meter swap. The display changes with the mode, showing cost and use in credit mode and remaining credit in prepayment mode⁹.

The information your meter transmits and privacy safeguards

A smart meter sends meter readings and the technical information needed for billing, meter operation and smart services¹³. It does not record conversations, browsing history, personal activities or details about individual appliances¹³. Smart meters only give data about how much energy is used⁴.

Personal information is not stored on the meter. Names, addresses and bank details are not held on the device itself¹⁸, and readings can only be shared with the energy supplier, who cannot share them further without permission¹⁴. The security of the system rests on controlled access, secure data processes and design to national technical and security standards¹³.

How often data travels depends on the service. Smart meters can record electricity consumption information every half hour of the day and transmit it, which is the granularity that half-hourly billing and time-of-use tariffs depend on⁵. Half-hourly data is what allows the energy industry to settle charges against actual use rather than estimates, which is why Ofgem expects it to help cut energy bills across the system⁵. Households can choose how much is shared: the default arrangements do not oblige anyone to hand over half-hourly data, and the supplier needs permission to use the data to offer new products and services².

Accuracy: certified by law, and the same as a traditional meter

By law, all smart meters have to be approved by and certified by the Office of Product Safety and Standards to prove their accuracy⁶. When it comes to measuring electricity or gas usage, smart meters are as accurate as traditional meters⁷. The Office for Product Safety and Standards ensures that electricity meters are accurate, working closely with energy suppliers¹⁹.

Smart meters are compliant with the Smart Meter Equipment Technical Specification, known as SMETS, which is the technical standard the equipment must meet²⁰. In practice this means a smart meter is not a less reliable measuring device than the meter it replaces; it is the same kind of instrument with a communications link added. If a meter is believed to be recording incorrectly, the accuracy dispute process for electricity meters exists for exactly that, and the supplier is the first point of contact¹⁹.

Smart meter installation is free, but savings depend on the household

There is no direct cost for a smart meter; any expenses are recouped through energy bills over time¹. The household is not paying a separate charge for the equipment or a fee for the installation appointment, but the cost of the national programme is spread across bills in the way network and policy costs always are.

The more important point is that the meter itself saves nothing. It measures and reports; the savings come from what the household does with the information. The data puts the household in control of its energy usage, making energy-saving steps possible that reduce its emissions²¹, but those steps are the household's to take. A household that installs a smart meter and never looks at the display will see no change in its bills beyond the end of estimated billing.

Where the money can be found is in behaviour and tariffs: seeing what individual appliances cost to run, shifting use away from peak hours on a time-of-use tariff, or dropping an expensive legacy tariff for a cheaper one. All of those require the meter's data and the household's action. For a fuller treatment of the costs, see smart meter costs.

Dual-rate and time-of-use tariff choices

With a smart meter, access opens to more flexible tariffs, including dual-rate tariffs³. Time-of-use tariffs use the smart meter to log electricity use and charge different rates during different time windows²². Access to time-of-use tariffs means cheaper rates during off-peak hours and incentives for energy usage on high-supply days¹.

This is the clearest practical benefit of the meter's ability to record use in half-hour periods: a tariff can be priced against when energy is actually used, rather than a single flat rate applied to everything. Households that can shift washing, dishwashing or electric vehicle charging into cheaper windows pay less for exactly the same energy. The meter does not do the shifting; it makes the shifting visible and billable.

The wider system benefit runs the same way. Half-hourly settlement lets the industry match supply and demand more precisely, which supports renewable generation whose output varies through the day⁵. Households that want to go further can join flexibility schemes, covered in our guide to household flexibility and reward schemes.

Using smart settings, traditional settings and changing provider

A smart meter that has lost its connection stops behaving like a smart meter. The meter may not work in smart mode when the household moves to a new supplier, and manual meter readings may need to be taken and submitted instead²³. A meter not operating in smart mode has usually lost connection with the supplier, lost connection after a supplier change, or been installed without being connected to the national communication system²⁴.

The switching problem is real but shrinking. A household with a smart meter can switch suppliers, but the new supplier might not offer all the smart meter services such as remote meter readings, and the meter may need replacing²⁵. SMETS2 is now the meter type for any new smart meter installation⁹.

There is a route back: the meter may work in smart mode again if the tariff or supplier changes again²³. And if a supplier goes out of business, the meter and supply continue, but smart functions may be interrupted until the new supplier takes over²³.

Who fixes meter problems

If a smart meter stops working, the supplier is the responsible party. Suppliers are responsible for maintenance and will fix or replace the meter as needed¹. A smart meter may stop recording the energy used, or may no longer send readings to the supplier²⁶, and either fault is the supplier's to put right.

Suppliers operate under guaranteed standards of performance for smart meters. If a smart meter installation fails due to a fault within the energy supplier's control, the consumer will receive compensation²⁷. Ofgem has set out these standards in a final decision covering the smart meter guaranteed standards, and it intends to review their outcomes in the first quarter of 2027²⁷.

Not every problem is a meter fault. In one case handled by the Energy Ombudsman, a consumer found that due to the location of the meter screen on the new gas meter they were unable to check the reading on the meter, an installation problem rather than an equipment failure, resolved through the supplier²⁹. If a supplier will not fix a fault, the Energy Ombudsman can take up the complaint⁹. For troubleshooting steps, see smart meter faults and troubleshooting.

Availability and the national installation timetable

Energy suppliers have been rolling out smart meters since 2012³⁰. The obligation has been extended repeatedly: it was extended to the end of 2020 and then to the end of 2021 in response to the pandemic³¹, and a new four-year framework ran from July 2021, covering the rollout period between 1 January 2022 and 31 December 2025³². Suppliers are now working to complete the rollout by the end of 2030⁸.

Coverage is already broad. Government expects a technical solution allowing smart meters to function in more than 99% of homes to be available, and its proposal was for 80% of homes supplied with energy by suppliers to have smart meters by the end of 2025³¹. Uptake grew from 62% in August and September 2023 to 68% in January 2025³⁴. The rollout is implemented by energy suppliers across the country, installing millions each year¹⁶.

There is no requirement for suppliers to install a smart meter on request, but households wanting one can contact their supplier⁹. Once the Department considers the rollout complete, responsibility for smart metering passes to Ofgem and Smart Energy Code governance³⁰. The full progress picture is in the UK smart meter rollout.

Tenants, homes with solar and moving home

Households that pay for their energy, whether owning or renting, can book to have a smart meter installed where it is expected to work in the property¹⁰. Private renters can choose a smart meter if the energy bills are in their name or they prepay for their energy; the tenancy agreement governs any duty to inform the landlord⁹. Whether a home is on a pre-payment plan or rented, it can benefit from a smart meter¹.

Homes with solar panels can have smart meters too, and the half-hourly record of use is what makes time-of-use and export arrangements workable; the specifics are covered in smart meters with solar panels. For renters in flats and shared buildings, see monitoring in flats and rented homes.

Effects on your household's self-reliance

A smart meter cuts one dependence and deepens another. It removes the estimated bill, the doorstep reading and the need to report numbers by hand: billing is based on actual use recorded in half-hour periods¹⁰. It gives the household a live view of its own consumption, which is the raw material of every deliberate saving, and it opens the door to time-of-use tariffs and flexibility payments that reward shifting use when the grid is strained¹.

What remains is dependence on the supplier and the national network. The meter's smart functions depend on a connection operated by the DCC and on the supplier's systems; if that link drops, the meter still measures but stops reporting, and the household is back to manual readings²⁴. The data flows to the supplier, not to the household by default, and using it for anything beyond billing requires permission or a consumer access device². A household that wants its energy data under its own roof can look at local data access and consumer access devices, and the wider question of what monitoring does for self-sufficiency is treated in smart meters, monitoring and energy independence.