Gas Bill Calculator

We've created this gas bill calculator to help you estimate how much you should be expecting to pay for your gas bill over any set period of time.

This may be because you are moving home and want to work out how much more or less you may have to pay, or maybe you are looking to switch tariffs and see how much you could save on your utility bills.

Whatever your reason, keep reading to see how to use our free energy bill calculator and find out what you need to know.

How to use our gas bill calculator

You need to start by deciding how many days you want to look at, one day, one week, one year or anything in between.

Next, enter the gas used over whichever unit you selected — for example, kWh per month when the period is months. Use a recent bill where possible; the Ofgem bands below are benchmarks, not household estimates.

The next two pieces of information you will need to get from your utility bill will differ depending on your energy supplier and tariff.

Your unit rate is how much you pay for each unit of gas, and your standing charge is a fixed amount you pay per day regardless of how much energy is used.

Once you put all these details in, you will automatically see a breakdown of your total unit charge over the period you set, the total cost of your standing charge, and your overall bill for that period of time.

What is a Unit of Gas?

A unit of gas is one kilowatt-hour (kWh), which is what your bill is priced in. Your meter, though, records volume — cubic metres (m³) on a metric meter or cubic feet (ft³) on an older imperial one — and your supplier converts that volume to kWh using a standard formula that accounts for the calorific value of the gas and a correction for pressure and temperature.

If your bill or your meter gives you volume rather than kilowatt hours, the gas meter reading calculator applies the volume-conversion formula for metric and imperial meters. Use the calorific value printed on your bill, then bring the converted kWh figure back here to cost it.

What is a Daily Standing Charge?

A daily standing charge is the fixed pence-per-day part of your tariff, charged regardless of gas use. This calculator multiplies the entered standing rate by the number of calendar days and adds it to the unit-rate cost of the gas entered.

How much gas a typical UK household uses

If you do not know your own usage, Ofgem publishes Typical Domestic Consumption Values — three bands rather than a figure per bedroom. The medium band is the one used to quote a typical annual bill, including under the price cap.

Low is a flat or a small, well-insulated home, often one or two people; Medium is the figure quoted as “typical” across the industry, including on the price cap; High is a larger home, or more people, or both.

Source: Ofgem, Review of typical domestic consumption values, in force since 1 July 2026 (decision ofgem-tdcv-2026). The monthly and daily columns are the annual figure divided by 12 and by 365; Ofgem publishes the annual figure only. Ofgem publishes one set of gas values rather than splitting them by meter type.

These values changed on 1 July 2026. The medium band was 11,500 kWh before that, so a bill quoted on the older figure is not comparable — the assumption moved, not the household. Real usage varies with the age of the property, how it is heated, how many people live there and the time of year, and is far higher in winter than any annual average implies.

We also have an electricity bill calculator and an energy bill calculator available (to calculate a combined gas and electricity bill).