Christian M. 3 min read

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 gas rates until 2024).

Energy Price Cap: We use the latest Energy Price Cap figures (1 April 2024 – 30 June 2024) 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 in April 2024. The Energy Price Cap figures are due for revision on 30 June 2024.

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

Estimator: Use our gas cost estimator if you want a simple gas cost calculation applicable to homes and businesses. It only takes into account gas usage and gas unit 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.

Extended Reading: How to submit a gas meter reading.

An example of a gas calculation

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 £84.14.

She concludes that her gas usage and cost are reasonable given the ongoing energy crisis. However, she still signs up for our notifications to receive better deals when they become available.

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) * Volume correction factor * Calorific value ÷ Conversion factor

Imperial meter gas consumption calculation:

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


  • 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 (find yours using the price cap checker) and use the following formula to get your outstanding gas cost:

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

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

£Gas Bill = £Gas Cost  * 1.05

How to calculate your gas bill from a meter reading

Our Gas Bill Calculator is designed to give you a breakdown of ALL your gas costs using only your (1) meter readings and (2) gas bill [optional].

If you’re unsure how to read your meter, read our in-depth guide.

If you’re only looking for a back-of-a-napkin estimate, use our super simple Gas Cost Estimator below, which only considers (1) gas unit rates and (2) gas readings.

Gas Cost Estimator

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 thermal collectors, and a heat pump can eliminate your need for gas by regulating temperatures using electricity or even biomass boilers if you live in an area with ample biomass supplies.

Extended Reading:

Available Calculators:

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


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 use, (2) your type of tariff, (3) your gas rate, standing charge, region and payment option, and (4) whether it’s a domestic or commercial property.

(1) The more kWh of gas you consume, the higher your bill. Gas heating and cooking are the most common uses.

(2) Your tariff determines your (3) unit rate and standing charge.

(3) The gas rate and standing charge vary depending on where your property is and how you pay for your gas. Direct debits are the cheapest, while credit is the most expensive.

(4) Domestic properties pay 5% VAT and are protected by the energy price cap. Business properties pay variable % VAT depending on their activities and are not protected by the price cap. Businesses can get help through the Energy Bill Discount Scheme.

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

A couple residing in a domestic property in Southern Scotland might use approximately 10,000 kWh of gas annually. If the current price cap remains consistent and they’re on a standard variable rate (as most people are), their yearly bill would amount to £792.67, including 5% VAT.

If living in a comparable flat in Liverpool and paying by credit, the same couple would expect to pay around £857.40 annually. This increase is due to the costlier credit payments and the higher rates in Merseyside.

What’s the most expensive part of a home gas bill in the UK?

Under the current price cap rates, gas consumption per unit rate is the most expensive part of any default tariff.

This assumes an average use of around 10,000 kWh of gas per year (fairly typical), irrespective of region and payment type. You can test this out on our calculator.

Other factors that affect the price are your (1) tariff, (2) gas use over the time of billing and (3) your region and payment option.

(1) Given the adverse gas market, If you fixed your tariff when it was cheap, you’re paying less than any current variable tariff.

(2) The longer the billing period, the higher the total daily standing charge cost. The standing charge (pence per day) is up to six times more expensive than the unit rate (pence per kWh), but given that an average household uses around 10,000 kWh of gas every year, the usage cost is much higher. The exception would be off-grid properties or those that heat their homes with heat pumps and avoid gas heating altogether.

(3) Under a default gas tariff, the region and payment option will directly affect your unit rate and standing charge, as nearly all suppliers have capped their prices to the maximum (as per the government Energy Price Cap).

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