Papple,

Each supplier charges different rates for different tariffs - I'm probably not telling you anything you don't know there. Depending on how you pay also dictates which discount you get (Monthly Direct Debit is usually the biggest discount). The way comparison sites work is to calculate from the monetary amount you've put in what the equivalent Kwh usage you have consumed based on the Kwh per pence ratio of the tariff you are on. So say you're with British Gas and you spent £500 - that may work out, with the discounts and everything factored in, to 5000 Kwh. But £500 with someone else who has a cheaper Kwh per pence ratio and different discounts may work out to be 6000 Kwh. So when the site calculates how much your usage would cost with an equivalent provider, and what your saving will be, it's based on this Kwh figure. Which is why it's important you identify who you're with, which tariff you are actually on AND how you pay currently to get an accurate quote.

 That's pretty much how I understand it anyway.

hello,

I'm slightly confused over the switching listed on here,

when I type in my correct postcode and usage (in £ per month) but put in gas supplier details/payment method/tarif that aren't specific to me I get  a total price of £683.22 (a saving of £212)

but when I put all my correct details in (the postcode usage current supplier tarrif payment method) it lists my total price as £843.70 (a saving of £54) 

I was wondering why this diference occurs,can anyone help?

cheers