When I check my Gas Bills, I am finding that, using the Calorific Value stated on page 6 of my Bill, the kWh used figure does not work out as per the value stated. This seems to be because the calculation was not made using the Calorific Value quoted. Usually it is only an error of plus or minus 0.1 of the stated value but it should be the correct value or else the bill is technically wrong !
Why can you not get all of the figures correct so that the bill can be checked fully?
Best answer by Transparent
Updated on 26/08/25 by Abby_OVO
On our live-billing platform, your energy charges are calculated and applied to your balance on a daily basis. The monthly email gives a summary of how much your total charges were for the previous month. You can log-in to your online account or OVO app (download for Android or iOS) anytime to view your up-to-date balance, detailed charges and usage. Find out more about how this works in our FAQs below:
In order to covert a m3 unit to kWh, we need to carry out a complex equation which involves taking into account the calorific value of gas. As this can change month to month, the calorific value we use to calculate your charges may differ slightly to the one used by your meter, which uses a set value of 39.2. As the calorific value changes so often, it's not practical for the meter to be constantly updated with it. However your monthly summary will use the up-to date calorific value.
When submitting your meter readings manually on your online account or OVO app (download for Android or iOS), you’ll only need to send us the m3 figure and we’ll do the rest. Find out how to read your meter reading manually here.
Hope this helps 
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Why is Ovo altering my bills after I have downloaded my copy and then using the altered bill as the start point for the next bill?
+8Hi
Do you have gas? If so, it might be updated to account for the calorific value.
However, we can’t answer this one very easily here. You’re probably better off calling 0330 303 5063.
+9There are occasional updates after initial issue. I had one where the energy support payment was added after the first issue. And of course the updated bill is the start of the new month
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OVO Energy Ltd, registered office 1 Rivergate Temple Quay Bristol, BS1 6ED, company no. 06890795 registered in England and Wales.
OVO (S) Gas Limited is registered in England and Wales (Company No. 02716495) at 1 Rivergate, Temple Quay, Bristol, BS1 6ED.
OVO (S) Gas Limited is part of OVO Group Ltd
