Are smart meters accurate?

Published 26 October 2026.

Almost always, yes. Every meter, smart or not, has to measure within legal limits, and when people dispute a meter it usually turns out to be fine. When a smart meter bill is wrong, the cause is far more often the readings not arriving, the wrong meter on your account, or the display’s prices than the meter itself.

The legal limits

Meters must be accurate to within small tolerances set in law, and a meter working within them counts as accurate. For domestic gas meters, the government’s review of meter disputes gives the limit as 2% either way at normal flow rates. Electricity meters have similar limits of a few per cent.

In that review, 77% of disputed domestic gas meters were found to be accurate. The government’s guidance on electricity meter disputes says the vast majority of meters tested in 2021 were working correctly.

What usually goes wrong instead

• The meter has stopped sending readings. At the end of June 2026, 3.1 million smart meters were in traditional mode, according to the government’s statistics. The meter still measures, but your bills go back to estimates until you send readings or it’s fixed. If your bill says “estimated”, this is the likely cause.
• The wrong meter on your account. Occasionally an account is linked to a neighbour’s meter. Check the meter serial number on your bill matches the one printed on your meter.
• Gas billed in the wrong units. Older gas meters measure in hundreds of cubic feet, newer ones in cubic metres. One unit of the old kind is 2.83 cubic metres, so a mix-up makes a bill nearly three times too high or too low.
• The display’s prices are out of date. The in-home display works out pounds from tariff details your supplier sends it; the kWh are what you’re billed on.
• Gas varies a little. Gas bills convert volume to kWh using a calorific value that changes slightly with the gas supplied, so the same volume can cost a little more or less. That’s normal, and it’s shown on your bill.

Check yours

1. Compare the reading on the meter itself with the latest reading on your bill or app. They should match, allowing for the days in between.
2. Switch off everything you can and watch the display. Electricity use should drop to your fridge, router and standby; gas should drop to zero with the heating and hot water off. If gas never stops, something may be burning around the clock: often a boiler keeping itself hot.
3. Switch on one thing with a known power, such as a 2 kW heater, for an hour. The meter should record about 2 kWh more than usual.
4. Download your half-hourly readings from your supplier and run them through the electricity or gas analyser. A pattern that doesn’t match your life, like big use while you were away, is worth raising.

If you think it’s wrong

1. Contact your supplier first with your readings and what you’ve found.
2. If you’re still not happy, ask them for an independent test. An examiner working for the Office for Product Safety and Standards visits, a replacement meter is fitted, and the old one is tested in an approved laboratory.
3. The test is free, but if the meter is working correctly you may have to pay your supplier for arranging it. If it’s outside the limits, the report says by how much and, where possible, for how long, and your supplier puts the bills right.

The government’s pages for electricity and gas meter disputes have the details. For problems with bills rather than the meter, Citizens Advice can help.

Common questions

Dispute process from GOV.UK’s guidance on electricity and gas meter accuracy. Gas meter limits and test results from the 2010 gas meter dispute review. Thinking about getting one? See are smart meters worth it?