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Working out yourself how much its costing from meter reads

  • 13 November 2018
  • 30 replies
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Hi there, simple question really, I just want to work out the cost of what i am using myself, using my meter readings, but it always seems to be confusing how they measure this stuff.
My rates are:
electrictiy 13.115p per kWh
gas 3.098p per kWh
So if on my meter I've used say 40 units for gas how can I turn that into a £ figure? (40 x 3.098p doesn't seem to work, it would be much too low)
And for electricity if I used say 300 does 300 x 13.11p give me the actual cost? (this seems like it could be the right figure but I'd like to be sure)
Hope that makes sense, many thanks in advance

Quick final question is when submitting readings is there any way to change the date? Sometimes I take a reading but don't submit it the same day
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Best answer by woz 13 November 2018, 16:11

hi MJK
There's some good news and some bad news on this.
The
calorific value isn't quoted on the statement, but it can be worked out from the statement*, but that's only when you've had the statement which sort of defeats the object of the exercise.
The good news is that it doesn't vary by a huge amount so if you use an average value for your calculations (I'd suggest 39.4 MJ/m^3 or MegaJoules per cubic metre) it will be near enough to get you well within the ballpark.

Or as suggested, better still just use the calculator
HERE which is close enough.


*You can work out what calorific value PP have used by the following
On your statement it says how many cubic metres youve used - call that C
On your statement it says how many kWh call that K

Calorific value = (K times 3.6) divided by (C times 1.02264)
so for example you used 40 Cu m. and your bill says they are charging you for 450 kWh
450x3.6=1620
40x1.02264=40.9056
1620/40.9056=39.6
so the Calorific value used by PP is 39.6
(When I put the 40 into the website above it returned 447kWh)

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30 replies

Userlevel 7
Badge +9
Hello MJK.
the electric is easy. As you done
13.115p x usage + membership=cost
Gas has to be converted into kwh
Should show figures on bill but its something like.
Meter units × calorific value x 3.098p +membership = cost.
Does that help?
When you give a reading it should be as you read it time, you cant post date readings.
Many thanks for your quick and helpful reply
Yes i thought the gas is more tricky, and thats the one I need to monitor most for central heating usage. I can't seem to find the calorific value anywhere as PP don't seem to issue formal bills where you'd expect to see this sort of details? I looked around and found you had previously referenced this caluclator at https://www.ukpower.co.uk/home_energy/gas_meter_readings will this work?
Userlevel 7
Badge +9
Hello again.
Yes that would work, just make sure you use the correct conversion metric or imperial. Would come out with very differant answers.
Userlevel 7
Badge +11
hi MJK
There's some good news and some bad news on this.
The
calorific value isn't quoted on the statement, but it can be worked out from the statement*, but that's only when you've had the statement which sort of defeats the object of the exercise.
The good news is that it doesn't vary by a huge amount so if you use an average value for your calculations (I'd suggest 39.4 MJ/m^3 or MegaJoules per cubic metre) it will be near enough to get you well within the ballpark.

Or as suggested, better still just use the calculator
HERE which is close enough.


*You can work out what calorific value PP have used by the following
On your statement it says how many cubic metres youve used - call that C
On your statement it says how many kWh call that K

Calorific value = (K times 3.6) divided by (C times 1.02264)
so for example you used 40 Cu m. and your bill says they are charging you for 450 kWh
450x3.6=1620
40x1.02264=40.9056
1620/40.9056=39.6
so the Calorific value used by PP is 39.6
(When I put the 40 into the website above it returned 447kWh)

Userlevel 7
Badge +10
Dammit, I wanted to help but you both beat me to it 😩😩😩😩😩😩😩😂. I do mine (leccy only) plus parents (duel fuel) both manually, and come out dead to the penny every time 👍, so I know where you’re coming from MJK 👍and once you get into the flow each month, it’s a piece of wee.
Userlevel 7
Badge +11
That's interesting, despite my now huge and overcomplicated meter reading spreadsheet, where all I do is enter the readings, not once have I managed to get it to reconcile to the penny. I can't figure out exactly where my error is, it's very close but not exact. I think it has something to do with the way the discount or the monthly fee is calculated.
I'm coming to yours for lessons Bev, tea one sugar please.
Bev;16374:
Dammit, I wanted to help but you both beat me to it ������������������������������������������������. I do mine (leccy only) plus parents (duel fuel) both manually, and come out dead to the penny every time ������, so I know where you’re coming from MJK ������and once you get into the flow each month, it’s a piece of wee.
Userlevel 7
Badge +9
Careful woz. Never heard anything again from the bloke who took bev out for a lunch date. 🏥
Userlevel 7
Badge +11
ha - good point, might have to swap the cups round...
Jon1;16387:
Careful woz. Never heard anything again from the bloke who took bev out for a lunch date. ������
Userlevel 7
Badge +10
LOL SOOOOOOOOOO much, both 😂😂😂😂😂👍👍👍👍👍

OK, firstly, pretty sure it’s the rounding up Woz; do it to four decimal places throughout and usually comes out spot on. OK, maybe it’s occassionally out, but sooooo teeny.

Secondly, I’m NEVER prepared for visitors 😂😂😂😂. Ask anyone how many times I say “If you want a ☕️, bring your own milk and sugar!” 😂😂😂😂😂Never ever got either in!!!

Thirdly, oooooooh my date 😂😂😂😂😂😂, saw him only yesterday and asked him if I could delay our date (yes I called it that, frightened the poor bugger to death 😂😂😂😂) til Spring. He agreed bless, so it’s still on 💕😂, just on hold 👍.
Userlevel 6
@Bev LOL, delay date until the spring? That's a no, not really interested, then 🙂
Userlevel 7
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LOL LOL LOL Gil, he’s a lovely old geezer bless, 82 ya bugger 😂😂😂😂😂, thought be bit cold for him at mo 😂😂😂😂

Anyway Gil, where ya been hiding?! Thought you’d died a little bit! 🙀
Userlevel 6
Bev;16431:
LOL LOL LOL Gil, he’s a lovely old geezer bless, 82 ya bugger , thought be bit cold for him at mo

Anyway Gil, where ya been hiding?! Thought you’d died a little bit! ������


But @Bev, that's where you come in to warm him up 😉....go on, make his winter warmer!

As for hiding, we had a weekend away in the big smoke for my wife's birthday. Brilliant weekend :checkmark:❤️
Userlevel 7
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😂😂😂😂😂😂😂😂😂😂

ah fab re ya London trip, what a beautiful gift 🎁for your wifey 👍
errr getting back to the subject... (though I'm glad my enquiry sparked such a frenzy of camaraderie!)....
Many thanks all, so here's what I did - I put 47 (wich is my actual Oct reading) into the calculator (I used imperial as my meter saus cubic ft, came out with 1487.9526, so to get £ is this right on my spreadsheet? - 1487.9526*3.038/100 = £45.20?
However if I look at PP's figures for recently, they gave 661.7kWh and said that was £27.52, but if we put that into the formula, 661.7*3.038/100 then equals £20.10, ao hows that or have I missed something??
Thanks in advance
Userlevel 7
Badge +10
So work out your gas units used since last month in M3.

So yours is 47 you say MJK. Then multiply 47 x 1.02264 (volume correction)

multiply x (calorific value) 39.4

Divide by 3.6

= usage in KWh
Userlevel 7
Badge +11
errr...
if your meter is in cubic feet you must be a very light user because 47 cu ft=1.33 m^3, and if you heat your house on gas I'd expect between 100 and 200 (approx) for a small to large house (mine was at the upper end of that because my family refuse to wear thick woollies!)
Using my spreadsheet, (available on request at a very competitive price (£0) if you're feeling brave and have hours or days to spare to figure it out),

**
THESE FIGURES ARE AT MY RATES,2.930p/kwh I can't work yours out unless I know which area you're in


47 cu.m of gas which seems very low, = 530kWh and costs £22.92 including annual charges and at a calorific value of 39.7 which is the value PP used for me,your calorific value may be different to mine*, see below. (it's accurate to a few pence)
Breakdown
Cost of gas exc vat,

**£14.79


Annual charge pro rata daily (for me) exc vat
£8.25 (there's an extra day in there as it's 31 days)

Discount -£1.21(ex vat)

Total £21.83+vat at 5%=£22.92

**661kWh works out at £26.75 or £26.53 if you use £8.50 for the monthly charge, rather than adding an extra day (and that's a whole new discussion)


MJK;16568:
errr getting back to the subject... (though I'm glad my enquiry sparked such a frenzy of camaraderie!)....
Many thanks all, so here's what I did - I put 47 (wich is my actual Oct reading) into the calculator (I used imperial as my meter saus cubic ft, came out with 1487.9526, so to get £ is this right on my spreadsheet? - 1487.9526*3.038/100 = £45.20?
However if I look at PP's figures for recently, they gave 661.7kWh and said that was £27.52, but if we put that into the formula, 661.7*3.038/100 then equals £20.10, ao hows that or have I missed something??
Thanks in advance
Userlevel 7
Badge +8
Interesting to see all the calculations, I thought there must be an easier way than all this working out calorific values and converting to kWh.
Obviously the results will be different depending on the area you live and cost per kWh, but after the first initial calculations, it is possible to work out the cost per unit (cubic meter ) shown on the meter, in using the figures WOZ provided it works out at 32.77 pence per unit, in my case it works out at 32.6542 pence per unit, plus 23.83 p per day monthly charge plus vat @5%.

WOZ in one of your posts above you say you would expect between 100 and 200 cu ft, is this per month or per quarter
Userlevel 7
Badge +11
hi Duppy
I didn't say that, or at least I didn't intend it to be interpreted as cu. ft, I said 100-200 meaning cubic metres a month.
Having re-read it I can see why you thought that.
The calorific value has to be calculated retrospectively because PP don't quote the value so it has to be worked out from the statement.

So...in order to calculate the kWh from the volume, you have to use an "average" value for calorific value (and calorific value can also vary by area). I use a default of 39.4 and I calculate it for my spreadsheet once I have the statement
(I realise that's not ideal for working out in advance but it's close enough)
The easier way if it's only the gas price you want is THIS
As far as the usage goes if you look at Ofgen Typical Domestic Consumption Values they range from 8000 to 12,000 to 17,000 kwh a year, mine is more.
If you take the range of value of 8k-12k -17,000 and assume 65% is used in the colder months that gives
5,200 to 7,800 to 11,000 kWh in the colder period

or 867Low to 1300Med to 1800high kwh a month
which equates, depending on Calorific value of somewhere between
77Low to 115Med. and 160High cubic metres a MONTH
Then add your daily charges less discount

My 100 to 200 cu.m a month was a guess, but it looks pretty close. Perhaps I mix in badly insulated circles but most of the people I speak to are in the medium or higher than high range, including me.

I agree, if you use between 32p to 35p per cu.m and about 24p a day charges all inc vat (half the discount applied as only one fuel) you'll be close enough

Duppy;16611:
Interesting to see all the calculations, I thought there must be an easier way than all this working out calorific values and converting to kWh.
Obviously the results will be different depending on the area you live and cost per kWh, but after the first initial calculations, it is possible to work out the cost per unit (cubic meter ) shown on the meter, in using the figures WOZ provided it works out at 32.77 pence per unit, in my case it works out at 32.6542 pence per unit, plus 23.83 p per day monthly charge plus vat @5%.

WOZ in one of your posts above you say you would expect between 100 and 200 cu ft, is this per month or per quarter
Hi there Woz, many thanks for your answer and really appreciate ypou spending the time to try and explain all this but my porr little unmathmatical brain is still reeling a bit.... you refered several times to cubic metres but mine is an old meter in cubic feet, so does 47 still seem low? I usually get up to about ~100 a month in winter months, as low as ~10 in summer months. Its a fairly big victorian terrace 3 bedroom house in Bristol if that helps (gas for hot water and central heating and cooking). Main urgent need to work this out is becasue I have lodgers and one of them is spending over 20 minutes a day in the shower, which seems rather excessive to me but before I enter into any discussion with her I really need to know if this is costing me anything signifcant. Very appreciaitve of some simple calcs that relate to my specific situaiton! (let me know if you need any more info)
Userlevel 6
Could I butt in and explain what I do, as I like an easy life :)

This online calculator https://www.businessenergy.com/gas/kwh-calculator.html
will convert either Cubic meters (m3) or cubic feet (ft3) to kWh

So, old school 10ft3 = 315.13kWh
Then just times that by the Pure rate of 2.888p per kWh = £9.10 (or put 2.888 into the calculator).

The question for me is how many ft3 is used by a 20 minute shower? - meter reading before and after?

Now I will butt out, good luck 🙂
THats Ok, also pls see attachment to show my meter. I have noted that 1 minute of the shower uses 1 of the smaller units, so it went from 77574 to 77575. Of course this is a very rough reading, it might have been just about to change to 5 when I started and it might have finished just past the 5, so I noted it also on the dial to the right on the meter and 1 minute used 1.3 on that. HOpe that helps!
Userlevel 6
Hi @mrk, that's not enough time to really know whats going off, I reckon its about 9p usage 😕. Too many factors going off in 60 seconds.

Do the readings start/finish for the full 20 minutes then it should give you more meaningful data 🆙
Userlevel 7
Badge +11
hi @MJK
Oh dear, perhaps your lodger has other problems..and what about the water? Is that metered, it probably costs more than the gas..we'll do that one another time...

Anyway to the question, first things first:-
Imperial meters measure in hundreds of cubic feet (100 ft³). If your meter shows a usage of 1, you've actually used 100 ft³.
100ft³ equals 2.83m³.

So with that in mind: (bear with me..I'll get to the point eventually)
If I was looking at this from scratch without knowing any figures, I'd guess that your shower used about 11 to 12kwh of energy, then I'd guess at how efficient your boiler was and what the losses might be in the pipework. If your boiler is old it could only be 50% - 60% efficient from boiler to shower, if it's modern it could be 80%, so lets assume about 65% of the gas you use is converted into heat so you'd need to provide about 18kWh of gas for the shower. But the shower doesn't last an hour so..
For 20 mins that would be a third so lets guess 6 kWh for a 20 min shower or about 18p (In reality it depends on flow rate, temperature etc so let's widen that to between 16p to 20p AS A GUESS
This is just a guess to get us into the ballpark...
(we hesitate to mention ballparks as Bev will fall about laughing..but that's not important right now..)

So with that in mind lets look at the figures you quoted.
First of all you can't do an accurate measure over a minute, unless you note exactly where the round dial is when you start and finish, and note all the digits.
Try to do the measurement over a few counted minutes and note all the dial and number positions/rotations
Here's an imperial meter photo guide from .
gov



The last two square digits are 10's and units so your meter as shown is reading Seven hundred and seventy five thousand seven hundred and fifty cubic feet, which is why when you submit figures you would submit 7757 which is really 7757 (x 100)

But taking on face value an increment on the reading of 1.3 on the dial??? (unclear what you meant) and ignoring the square digit because as you said you don't know where it started , in one minute, that would equate to 1.3 ft³ =26ft³ in 20 mins, That would work out at about 8kw 0r 23p, but then your measurement is very rough and we don't know the efficiency of your heating system.
So for the moment the answer lies between 16p and 23p plus water.
I have a feeling this thread is going to continue, if so we'll need to know a bit more about your heating system
I hope the lodger doesn't read this, she may get spooked out thinking you're timing the showers!
Userlevel 7
Badge +10
Soooo true Woz re ballpark 😂😂😂😂😂😂but loving long 🚿talk too 👍👍👍👍, remember my polly hee? At least 25 mins on these cold winter mornings, then again when get home 🚿🚿, then again in eve 🚿🚿🚿👍😂👏
Userlevel 6
This stuff gets so addictive (someone help me :foldedhands:) :rolleyes:

When our shower was used today, (interestingly that was around 20 minutes, must be a gi** thing, NO, lets not go there!), I measured the power used.

We have a 10kW electric shower and my electric measurement system showed it used 3.4kW, which for 10kW @ 20 minutes is spot on 🙂.

SO, assuming is takes 3.4kW of power for a 20 minute shower, even though your using your gas boiler, the law of physics would also say that roughly, your 20 minutes would also need 3.4kW. But (big but) a gas boiler is no where near as efficient as an electric shower (reasons for that is a topic in its own right) so lets assume it would take three times as much energy, ie 10.2kw.

Therefore the Pure costs of 10.2kw of gas would be only 29.5p

For me, I don't think this is worth "fighting" (not in our house anyway :)), even if you said "10 minutes maximum" you would only save 15p each shower.

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