Are the calorific values used to calculate monthly gas charges shown on the online account?

  • 18 January 2019
  • 16 replies

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  • Carbon Cutter*
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I've got two questions about the new OVO online account pages.

1/ Are the calorific values used to calculate monthly gas charges shown anywhere on the OVO pages? My apologies if they are displayed, but I've missed them.

I raise the question because you need to know the relevant calorific value if you're trying to check your gas charge calculations - right through from the meter readings to the final amount. Under the old arrangements the relevant averaged calorific value was recorded on your monthly gas bill. As far as I can see you can't download an 'old-style' gas bill under the new arrangements - and I don't think the calorific value is included on the new web pages.

I know you can download calorific values via the National Grid website - but this is a palaver because you have to filter out the daily values relevant to your local zone and then average them over the charging period. It would be much more convenient if the relevant figure was included alongside the other charging information on the OVO pages.

2/ My second question is to ask whether there is an easy way to download a record of the electricity and gas meter readings from the beginning and end of the monthly charging period. I'm not sure how charging periods work under the new OVO regime, but OVO is now emailing me my electricity and gas charges for the previous calendar month, so I'm working on the basis that my charging period is now each calendar month. When I check the monthly charges I therefore need to know the meter readings from the beginning of the first day and end of the last day in each month.

Again, the old-style gas and electricity bills made it easy because they included the start and end-of-period meter readings used to work out your bill.

I appreciate that you can still see this information using the bar graphs on the new monthly usage pages. For anyone who doesn't know, you could mouse over the bars representing the first and last days of the month. Mousing over the bars launches pop-up windows showing start and end-of-day meter readings. You can then subtract the start-of-first-day reading from the end-of-last-day reading to give you the total number of units consumed in the period.

To be fair, I think this pop-up access to your meter readings is rather neat, but it would be very convenient if the OVO pages additionally displayed the relevant start-of-the-first-day and end-of-the-last-day meter readings alongside the other charging information.

Displaying these two readings for each charging period as part of the other pages would also give customers a way of printing these key meter readings - making it easy to retain a permanent record. A problem with the pop-up approach is that, as far as I know, you can't print the pop-up windows or export them as pdfs. The only way you can 'grab' the information is to screenshot the relevant part of the web page while the pop-up is displayed. This is okay as a workaround, but simply reproducing the key meter readings alongside the other monthly charging information would make life easier for those of us who like to check our bills and keep a record.

Again, I'm happy to stand corrected if I've misunderstood how the new OVO pages work. Please put me right.

Best answer by Paul_OVO 30 January 2019, 14:49

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Updated on 31/07/23 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.


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 that you can find online here.


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 :slight_smile:

Userlevel 1
Many thanks for the response and for explaining that charges are calculated daily. I look forward to future developments regarding the display of calorific values and meter readings. Hopefully it will also become possible for users to capture this information for their own records. Thanks again. Rob

Just put the Daily Calorific Value on your website!!!!! I can then check daily have a more accurate figure to put on my own spreadsheet. 
I've looked on the National Grid website and it is not user friendly. Technical terms I cannot understand, etc etc.

Knowing where I live  OVO should be able to give me a number for my area.



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Hi there @Bright1 !

This is actually a bit of an old thread, so I’m not sure if things have changed since the initial discussion. I’ll go ahead and ask @Tim_OVO and @Jess_OVO if there’s been any updates since then, as I don’t think Paul will be available right now.

I think the Support Team might also be able to help you identify which values to look for on the data explorer. It looks like the link is broken, so I’ll ask for that to be fixed as well. The correct one should be for the main site, and for the actual data explorer itself. You’ll want the second one if you’re after the raw data.

Thank you. It may only be difference of a few pounds over a year, but with the terrifying increases in cost of fuel every penny counts. 
Kind regards

Userlevel 7

Hi @Bright1 and Welcome to the OVO online community,


You’ve managed to dig out this archived topic and spotted some edits that need to be done so thank you for highlighting this as a question which is still being asked.


I’ll update the links provided in the Best Answer above as our community volunteer, @Blastoise186 has helpfully found the most up-to date source of the calorific value info. Unfortunately this is something that is not yet shown on your online account but I’ve passed your comments on as we’re always keen to hear on ways we could improve the online tools available to you.


How do you find the other online usage tools? Have you had a chance to get to grips with OVO Greenlight yet? 


Thank you. The fact is I don’t know my way round the forum. Haven’t really needed to use it in the past.
Like many other people I have always ‘cut my coat according to my cloth’.
I will not burden you with my opinions of those who haven’t been told ‘there are no pockets in shrouds!!!!

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No worries. :)

Everyone has to start somewhere after all! Don’t worry if you accidentally post in the wrong thread, we’ve got ways to fix that sort of thing. A quick touch of Moderator powers and Tim or Jess can easily fix things up, free of charge. If you ever need help, you’re always welcome to stop by and we’ll help you out. I also tend to monitor the forum using the recent activity feed anyway, so I will always see pretty much anything that gets posted, no matter which category it’s in.

I’ll try to check for any other references to that particular link, in case any need fixing. If there are any, I’ll ask for those to also be fixed in the background.

Thank you again.

kind regards

Hi all,

I was recently switched from SSE to OVO (on 28 June 2022, to be exact) for my gas & electricity supply. I like to be very on-top of what is going on with my utilities, so I keep detailed records of all metre readings and double-check the calculations made in my bill.

I’ve noticed two things on my OVO bill that are different from my SSE bills of the past.

  1. OVO don’t provide the calorific value of the gas supplied for each billing period. SSE did this, allowing me to calculate my estimated gas bill, but OVO don’t. Why not?
  2. My OVO bill states an opening reading provided by me (which is correct), a reading for the last day of the billing period provided by me (which is correct), and a “Closing read as of <last day of billing period>” which is slightly higher than the reading provided by me for the last day of the billing period. I tried to ask someone on the phone about this but they didn’t understand/know, so can someone enlighten me as to what this value is and why it’s higher than the metre reading I provided?

I have yet to receive a second bill to see if this spuriously generated “closing read” matches next month’s “opening read”… If it doesn’t, there’ll be trouble! 😉

Thanks for your help and have a great day!

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Hi @Sirk !

I’m one of the forum volunteers here. Just so you’re aware, I can’t access your account myself and I don’t work for OVO or SSE.

As far as I’m aware, there should be the calorific value data on every bill, but you might need to download the PDF versions to find it. Alternatively, if you look it up on the National Grid Data Item Explorer at you should be able to find the data you’re looking for. And there’s a ton more on there as well in case you’re curious.

As for the closing readings, I don’t have gas myself but my electric bills all show the opening and closing readings for each statement matching up perfectly. It’s worth bearing in mind however, that gas readings need to go through additional calculations before being verified - and if the Calorific Value happens to vary, it can change things a little.

Userlevel 7

Hi @Sirk,


Do you have a smart meter? If you don’t and you submit a manual reading a bit too early, an estimated meter reading is created for the exact billing period. It will count from your last submitted reading, and use your ‘future annual consumption’ to count up however many day’s worth of usage need to be estimated. 


You’ll never be charged twice for the same energy though. If you haven’t got a smart meter, consider getting one and we’ll get your meter readings every 30 minutes! 

As I am new to OVO from SSE, I think I have fathomed out the workings of my first OVO bill. Only one thing that seems to missing from my OVO bill that was on my SSE bill is the calorific value used towards accurate calculation. All it says on the OVO bill is to view the National Grid site for these values. I do know the value fluctuates and that probably an average of the fluctuations is used the finalize the figures but to me the actual figure used should be shown on the bill to enable myself to accurately check OVO figures to the penny. If anyone is interested I could put the National Grid values for each calendar month on this site.

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I do know what you mean about seeing the calorific value @JGANLEY . I remember using that to double check my bills in the past. 
I believe (but may be wrong) that as NGC issues daily values, the data is calculated on those daily figures and so giving an average might be misleading 

Yes you are correct @BPLightlog. The NGC does issue daily values, this though does enable an average to be calculated for over the period of the bill. However on my first bill nowhere does it show how or what CV OVO have used to include in the calculations. As I mentioned the SSE bill did show the figure and that figure always provided accurate results. SSE did not ask the bill owner to look at another site to fathom it out themselves. Again I think OVO should give a full explanation on how they achieve the CV value, plus how they use it. Small amounts I know but millions of users could add up to a large amount.

Excerpt from SSE gas bill, leaving no ambiguity when calculating costs.

Converting to kWh

This is how we convert gas units into kilowatt hours (kWh):

137.55 metric units used

x 1.022640 volume correction

= 140.66 corrected units

x 40.1 calorific value ÷ 3.6 to convert to kWh

= 1,566.79 kWh

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I don’t disagree at all @JGANLEY I just presumed that various volumes at various CV’s would be difficult to follow. 
I see that you’ve found a thread from some time ago on this subject and that might be the best route for any updates