Gas Bill Calculator

Discover exactly how much your home gas is costing you with AquaSwitch’s unique home gas calculator.

✅ Auto-fills your latest price cap rates based on your (1) region and (2) payment method.

✅ Available for both standard variable and fixed-rate tariffs.

✅ Includes 5% VAT on final bill calculations.

Calculator notes:

Multi-tariff Functionality: Suitable for default standard variable rate tariffs (fluctuating with market conditions) and fixed-rate tariffs (i.e., homes that fixed their energy rates for 2026).

Energy Price Cap: We use the latest Energy Price Cap figures (1 January 2026 – 31 March 2026) compiled from official sources to auto-fill your unit rate and standing charge for default standard variable rate tariffs.

VAT: We include the reduced 5% VAT charged on all home energy bill calculations where explicitly mentioned.

Customisable calculation period: Choose your calculation period to match your gas consumption reporting (in kWh), which is different for everyone depending on their meter type.

Updates: This calculator was last updated on 31 December 2025. The Energy Price Cap figures will be updated in the first week of March 2026.

Limitations: Any gas bill calculations beyond this price cap period may suffer from reduced accuracy due to the quarterly changes in price cap rates.

How does the gas bill calculator work?

Here is how the gas bill calculator works:

Find your gas meter and take a gas reading by reading the dials and noting the units (m³ or ft³).
Find a previous gas reading on your most recent gas bill or your own personal log and note the time between readings in days.
Select variable or fixed tariff. If unsure, select variable tariff, as most households are this type of tariff.
1. Variable tariff: You don’t need to research your rate; our calculator will automatically find your rates based on your postcode and payment method.
2. Fixed tariff: Insert your gas unit rate (pence per kWh) and standing charge (pence per day), which you can find on a recent gas bill.
We will show you the breakdown of your gas costs (£) and your total gas bill estimate for your custom period or on a monthly/annual basis.

Gas bill calculation example

Christine has just purchased a small flat in Llanberis (North Wales) and is trying to keep track of her costs, including her gas usage. She goes to her old-looking gas meter and takes a reading of 7,008,365 ft³.

The previous owner gave her a recent gas bill that indicates she’s paying a standard variable tariff by direct debit. This means her supplier will charge her the latest Energy Price Cap rates.

According to the bill, her last registered gas meter reading was 7,005,215 ft³, taken 34 days prior.

Christine opens the AquaSwitch Gas Bill Calculator and follows the simple workflow, inserting both imperial meter readings and selecting her region as “N. Wales and Mersey” on the variable tariff route.

She finds out that she has used 1,069 kWh of gas and is given a clear breakdown of all her gas costs. Her total bill, including VAT for that period (if she was billed there and then) would be £75.59.

Christine also reads and uses our Electricity Bill Calculator to determine what her electricity costs her. She also reads our article on the average electricity usage to see if her energy usage can be reduced to save her some money.

How to work out gas consumption manually

If you want to manually work out your gas consumption, you will still need your gas meter readings and rates.

If you’re on a variable tariff (like most households), use our price cap checker to find your rates based on your (1) region and (2) payment method and avoid doing tedious research on the government’s website.

The first step is to calculate the energy usage in kWh, depending on whether you have an imperial or metric meter:

Metric meter gas consumption calculation:

kWh = Difference in gas meter reading (m³) x Volume correction factor x Calorific value ÷ Conversion factor

Imperial meter gas consumption calculation:

kWh = Difference in gas meter reading (ft³) x Conversion factor to cubic metres x Volume correction factor x Calorific value ÷ Conversion factor

Where:

The volume correction factor is an industry figure to account for atmospheric pressure, typically around ~1.02.
Calorific value adjusts for changes in the composition of gas when burned. It can vary slightly per supplier. Typically, ~39.2 MJ/m³ is considered a reasonable estimate.
The conversion factor is used to convert from joules to kWh, which is 3.6.
The conversion factor to change from ft³ into m³ is ~0.028.

Once you have your energy usage in kWh, you can combine this with your gas rates and use the following formula to get your outstanding gas cost:

£ Gas Cost = (Gas unit rate x Gas energy usage) + (Standing charge x days between readings) x 0.01

For your final gas bill, you must also add 5% VAT to your total gas cost:

£ Total gas bill = £ Gas Cost x 1.05

How can I reduce my gas usage?

Where do we start? Most homes and businesses in the UK are sub-optimal regarding gas usage because of bad habits, old boilers and inefficient insulation.

You can analyse your gas consumption. If you don’t have a gas smart meter, you can look at your consumption in hours, historical gas bills or your manual meter log if you have one (i.e. periodically writing down your gas meter measurements).

This will help you understand your gas usage habits. If the difference between winter and summer is significant, your heating and insulation systems may need a revamp. This is a likely conclusion given that UK buildings are infamous for poor insulation.

Otherwise, installing commercial solar panels, solar batteries, solar water heating, and a heat pump can eliminate your need for gas by regulating temperatures using electricity.

Available Calculators:

We’ve built several calculators to assist you in estimating both home and business utility costs:

Gas bill calculator – FAQs

In this section, we answer some frequently asked questions regarding your typical gas costs in the UK!

How much does gas cost in the UK?

The cost of gas in the UK is influenced by (1) your gas consumption, (2) your agreed gas tariff, and (3) whether the property is domestic or commercial.

(1) The more gas you consume, measured in kilowatt hours (kWh), the higher your overall bill. Gas used for heating and cooking typically makes up the largest share of household gas use.
(2) Your tariff sets the unit rate you pay per kWh, along with the daily standing charge. Together, these determine how much you are billed each month.
(3) Domestic properties pay 5% VAT and are protected by the energy price cap. Businesses pay VAT at 20% and are not protected by the price cap.

Here are some examples of typical home gas costs using our calculator:

A couple living in Southern Scotland might use approximately 10,000 kWh of gas annually. If the current price cap remains consistent and they are on a standard variable tariff, their yearly bill would amount to £721, including 5% VAT.

If living in a comparable flat in Liverpool and paying by credit, the same couple would expect to pay around £727 annually. This increase is due to higher tariffs for credit payments and higher regional rates in Merseyside.