How to read a UK energy bill
A UK gas or electricity bill is built from two charges: a fixed amount for every day, called the standing charge, and a price for each unit of energy used, called the unit rate.
The terms, in plain words
- Standing charge
- A fixed amount charged for every day of the bill, even on a day you use no energy.
- Unit rate
- The price of each unit of energy you used, in pence per kilowatt hour.
- kWh
- Kilowatt hour, the unit your use of both electricity and gas is measured in.
- Actual reading
- A reading taken from your meter, so the bill charges for the energy you actually used.
- Estimated reading
- A figure the supplier worked out without reading your meter. The government’s guidance on gas meters says sending your own reading can avoid an estimated bill.
- Calorific value
- A measure of how much heat energy the gas holds. Gas meters record a volume, and the bill uses the calorific value to turn that volume into kWh.
- Tariff
- The package of prices and conditions your supplier charges you on.
- Fixed tariff
- A tariff with a fixed end date.
- Standard variable tariff
- A tariff with no fixed end date.
- Energy price cap
- The most a supplier can charge for each unit of energy and for the standing charge. It does not limit the total bill: the more energy you use, the higher the bill.
- Economy 7
- A tariff with one unit rate at night and a different one during the day.
- Direct Debit
- Payment taken from your bank account each month, quarter or year, as a fixed or varying amount.
Bills for energy used more than a year ago
Under Ofgem’s back-billing rule, you do not pay for energy used more than 12 months ago if you never had an accurate bill for it. The rule does not apply if you stopped the supplier billing you accurately, for example by blocking access to your meter.
If you think the bill is wrong
Ofgem gives the supplier 8 weeks to fix a problem you tell it about. If it is not fixed by then, or the supplier sends a deadlock letter saying it can do no more, you can take the complaint to the Energy Ombudsman.
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Sources
- Ofgem: How your electricity or gas bill is calculated
- Ofgem: Energy price cap and standing charges explained
- Ofgem: Energy terms explained
- Ofgem: What to do if you get a back bill
- Ofgem: Complain about your energy supplier
- GOV.UK: Gas meter readings and bill calculation
Checked against these pages on 28 September 2026. This page explains the bill. It does not say whether a tariff suits you or whether the figures on yours are right.