Gas supply - calculation of cost

[Mr-H]

Does anyone have such a thing as a spreadsheet which will calculate the cost of their gas simply by using two meter readings? I use Npower, but believe that almost all companies use the same type of calculations (although the rates used might differ) insofar as they use a calorific value, then a correction factor, then a consumption profile etc. etc.!! I just thought that if anyone already had this spreadsheet and it worked (and if they were willing to let me have a copy) it would save me trying to work it out!! Thanks (hopefully!)

[buildersmate]

You don't need a spreadsheet - far too complicated. A simple 4-function calculator will do the trick.
Meters measure in Units of 100 cubic feet. So you deduct one reading from the other to get how many cubic feet of gas you used.
The calorific value of gas varies (a little) from region to region - this is the amount of energy created by burning a Unit measure of gas. A rough measure is 100 cubic feet of gas produces 30kWh of energy.
So multiple the number of cubic feet used by the caloric value (shown on the bill) to establish how much energy you were supplied with.
The price of gas is also shown on the bill priced in pence per kWh. Now multiply by this figure by that above and you know what your Bill should be.
If the companies go tinkering around with consumption profiles, life may become a bit harder, but the above is the valid way to establish what you used.