How the gas and electricity comparison site works

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The calculator works out how much each supplier will charge you, for a year, based on the latest prices available. Transferring is also made easy with straightforward transfer applications.

The objective is to make the price comparisons and transfer applications as quick and easy as possible using the speed and benefits of Internet technology.

Summary of process:

1. The calculator works out the amount of kilowatt hours of gas and electricity you use, and multiplies this up using each suppliers tariff details, to show the total cost each supplier will charge for the forthcoming year, based on latest prices available.

2. The results list shows the suppliers in order from least expensive to most expensive, and shows the savings compared to your existing supplier(s).

3. Quick links are available so you can switch easily.

More detailed process:

The database behind the website has a list of all suppliers and tariff types and this is updated with new tariffs when they are issued by the suppliers. These are shown on the price updates page.

The calculation is carried out in two steps.

Step 1: Establish the amount of kilowatt hours used.

When you enter your existing supply details, you can either enter A) the amounts you pay, or B) the kilowatt hours that you use.

A) If you enter the amounts you pay, the calculator first of all "back calculates" the amount of kilowatt hours that this would buy from your existing supplier using their current tariffs used in the calculator. (See Note 1 below.)

B) If you enter the number of kilowatt hours you use, the calculator starts from this point to work out the future cost calculations.

The first step therefore is to establish the number of kilowatt hours that are used for each supply.

Step 2: Calculation.

Once the number of kilowatt hours are calculated (either from option A or B above), the calculator then works out what each supplier will charge you for a year for this number of kilowatt hours.

This is done by getting each supplier's tariff details from the database and multiplying them by the kilowatt hours. It takes in to account the tariffs for different levels of usage and for day and night tariffs in the case of economy 7 meters.

It also adds on the annual total of the daily standing charges where applicable, and takes off all the discounts that apply for each supplier.

VAT is included in all costs because this is part of the cost paid by domestic users.

This produces a total cost that each supplier will charge for this number of kilowatt hours for the next year based on their latest tariffs.

Step 3: Results.

Having calculated what each supplier will charge, the calculator sorts the results from lowest cost to highest cost, then works out what the difference in cost is compared to the cost you would be paying with your existing supplier.

It puts all this information in a table and this is what you see when you have clicked the calculate button on the input page. It also adds the percentage savings at this point.

Everything happens very fast (in the blink of an eye) and depending on the speed of your computer, the results are displayed virtually immediately.

At this stage, you can see the tariff details by clicking on each suppliers "Cost" figures, and you can see further information by clicking on the information icon next to each suppliers name.

Step 4: Easy transfer.

There are links provided to all suppliers application forms or websites so it's easy to go from the results page straight to the application forms.

Application forms sometimes ask for meter reference numbers if the automatic process can't find them in the national database, and there are a variety of pieces of other information that suppliers need to take new applications. earns a small fee from some suppliers for transfer requests. Not all suppliers contribute, but this does not affect the results in any way. This fee is paid by the suppliers and you do not pay anything so this service is free for you to use. The tariffs are the same wherever you complete your transfer application.


The entire process is designed to be quick and easy and to take advantage of Internet technology.

Note 1.

The objective is to obtain a figure for kWh's to use to work out how much the future costs will be. When there have been price changes, slight variation in total kWh's used in a year may arise because, when the current bills are entered, the calculator uses the current or newest prices available, rather than the actual tariffs that were charged during the past year, to work out the kWh's. If the old prices were used, the number of kWh's would be higher (if the old prices were lower than the new prices). This variance, however, is not material as far as the comparisons for future costs is concerned because the same resulting number of kWh's is used to work out what each supplier will charge for future costs, and the savings are shown between the suppliers future costs. In fact, if the higher usage was used, the savings would be a bit higher (if old prices are lower than new prices.) It's better to use actual kWh's used, but by using the amounts paid, this produces the results table showing how suppliers prices compare with each other for the future year based on latest prices available.

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