Do smart meters give more accurate bills?

The accuracy is not a marketing claim from meter makers. Suppliers publish quarterly figures on how many of their smart meter customers receive accurate bills, and these can be compared directly. The rest of this page sets out what those figures show, what a smart meter will not do for your bills, and the situations where estimates can still creep back in.

What the supplier figures show

Suppliers' published customer service statistics include a "bills accuracy (smart meters)" figure, and the spread between companies is wide. For January to March 2026, 100Green reported 99.8%, Ovo Energy 98.52%, ScottishPower 97.55% and Octopus Energy 96.44%, while British Gas reported 88.12%⁴. In other words, even the lowest of these suppliers billed roughly nine in ten smart meter customers accurately in that quarter, and the highest billed almost all of them.

The expectation is not new. In an early smart meter trial dating from 2007, 27% of trialists felt the meter helped them get more accurate fuel bills, and 21% felt it helped them get lower ones¹³. The mechanism is simple: the meter measures the energy, the readings reach the supplier without anyone walking to the cupboard with a torch, and the bill is calculated from the actual figure. Where the published figures fall short of 100%, the causes are mostly in the delivery of readings rather than the measurement itself, which is the subject of the section below.

What a smart meter will not do

A smart meter will not lower your bills by itself. It does not automatically save energy or money; the savings, if any, come from acting on the information the meter gives you¹¹. The in-home display helps you keep track of how much energy you are using as you use it, and that visibility is what makes practical changes possible, but the meter makes no changes for you¹².

It is also worth being clear about who has paid for the rollout. Energy companies should not tell you smart meters are "free", because ultimately you pay for them indirectly, through your energy bills¹⁵. The meter is a measurement and billing tool, not a saving in its own right.

For a household thinking about energy independence, the honest framing is this: a smart meter gives you accurate data and access to time-of-use tariffs, but it does not reduce your dependence on your supplier. Except by switching, you do not control the tariff your supplier sets, though you can change how much energy you use. If you want to go further, the data a smart meter produces can be used to size a solar and battery system or feed a home energy management system.

When estimates come back

The main weak point is not the meter's measurement but the delivery of readings. If the meter loses its communications signal, your bills may temporarily become estimated, you may need to submit manual readings, and the in-home display may stop updating correctly¹⁶. The meter itself keeps measuring accurately throughout, so no usage goes unrecorded; it is the automatic sending that pauses.

A meter that has dropped out of smart mode, sometimes called dumb mode, is a second case. Such meters still accurately measure energy usage and work like a traditional meter, but they no longer send readings automatically, so estimates can return until the meter is restored¹⁰. Switching supplier or tariff can be a trigger, and the meter may work in smart mode again once the change completes¹⁷. If your supplier goes out of business, your account moves to a new supplier, and your meter may similarly need attention before it is fully smart again¹⁷.

There is also a backstop when things go wrong at the supplier's end. Under Ofgem's guaranteed standards of performance for smart meters, if an installation fails due to a fault within the energy supplier's control, the consumer receives compensation¹⁸.

How the readings reach your supplier

Smart meters enable accurate billing by automatically recording energy use in half-hour periods¹⁹. Your smart meter records your electricity use in near-real time, and every half hour for gas⁹. This half-hourly record is what makes both accurate billing and time-of-use tariffs possible, since a supplier can only charge different prices at different times if it knows when you used the energy.

Not all of that detail flows to your supplier by default. Suppliers are automatically allowed access to monthly consumption data to ensure accurate billing; anything more detailed depends on your consent²⁰. The readings travel over the Data Communications Company's secure network, and with smart meters suppliers get accurate and reliable readings automatically, billing you only for the energy you have used²¹. You can read more about what is collected and who can see it in our guide to smart meter data, and about the network itself in how smart meters communicate.

The rules that keep suppliers honest

The accuracy of smart meter billing is not left to goodwill. Ofgem's guidance on smart meter performance sets out what meters in smart mode provide: real-time information on your energy usage, more accurate bills, and access to more flexible tariffs²². The guaranteed standards of performance, finalised in Ofgem's January 2026 decision, put defined obligations on suppliers, with compensation payable when an installation fails due to a fault within the supplier's control¹⁸.

The rollout itself is also an obligation on suppliers, not on households. The government requires energy suppliers to offer smart meters to their customers, but customers do not have to have one²³. So the duty to offer, install and maintain the meters sits with the supplier, and the published bills accuracy figures let you see how each company is actually performing before and after you switch. If things go wrong, the Energy Ombudsman handles complaints that a supplier has not resolved.