How to read a gas meter
The reading itself is easy. Knowing which type of meter you have is the part that matters, because the two differ by a factor of 2.83.
Which type do you have?
Metric meters measure cubic metres and say m³ somewhere on the face. Digital ones usually show five digits before a decimal point.
Imperial meters measure hundreds of cubic feet and say ft³. They are older, usually have four dials or four large digits, and are the ones with a row of small clock faces.
If it is not marked, count the digits before the decimal: five suggests metric, four suggests imperial. Your bill also states which it holds on record — and if that record is wrong, every bill has been wrong by a factor of 2.83, which is worth checking.
Digital metric meters
Read the digits left to right and stop at the decimal point. Ignore anything after it and anything in red. Some meters cycle through several displays; the one you want is the plain volume total, often labelled VOLUME or M3.
Imperial dial meters
Read the dials left to right, taking the number each pointer has passed rather than the nearest one. Adjacent dials turn in opposite directions, so check the numbering on each rather than assuming.
Read only the dials with numbers 0 to 9. Ignore any dial marked 100, 10 or with a red surround — those are test dials and are not part of the reading.
Why the type matters so much
Gas is billed by energy, and converting volume to energy starts from cubic metres. One unit on an imperial meter is 2.83 cubic metres. Treating an imperial reading as metric makes the bill roughly a third of what it should be; treating a metric one as imperial nearly trebles it.
So if your own calculation comes out wildly different from your bill, this is the first thing to check. The full conversion is in how to calculate a gas bill.
Safety
Reading a meter means looking at it and nothing else. Do not remove any cover, adjust any fitting, or touch the pipework. If you smell gas, do not use switches or a phone in the building — leave, and call the National Gas Emergency Service on 0800 111 999 from outside.
Once you have two readings, the gas cost calculator converts them to kWh and works out the cost.