Here’s how
we work out your bills
Understand
Make sense of our credit meter
tariffs with different unit rates
Fair
See how all our customers pay
a fair share of fixed costs
Example
Use our worked example to see
how we calculate your gas bill
Understand
Fair
Some of our credit meter tariffs have two rates for the units of gas and electricity you use
(also called kilowatt hours or kWh):
Some of our credit meter tariffs (and all our prepayment tariffs) have a daily standing charge that
helps to cover the fixed costs we have to pay in supplying energy to you, e.g. distribution and
metering costs. For our credit meter tariffs with no standing charge the money we collect through
the primary unit rate goes towards these fixed costs.
• Primary unit rates (labelled as ‘first’ on your bill) are charged at a higher rate
• Secondary unit rates (labelled as ‘next’ on your bill) are charged at a cheaper rate
The primary rate units are applied to individual billing periods (i.e. the periods reflected in your bills)
as follows:
• For electricity the primary rate units are charged evenly through the year at 8.33%
(or 60.7 units) per month (that’s about 2 units a day), adding up to a maximum of 728 units
a year.
• For gas the primary rate units are charged on a seasonally adjusted basis, with more primary
units being charged in the winter months, adding up to a maximum of 4572 units a year as
shown in this table:
Months
Maximum units charged
at primary rate per month
• For electricity we charge the primary rate units evenly throughout the year because electricity
use is more consistent across the year.
We’ll charge you at the primary unit rate for the total number of primary units applicable for a
billing period, as long as your total consumption is at least equal to the total allocation of primary
units for that period, and regardless of your usage in the individual months in that period.
Maximum percentage charged
at primary rate per month
Nov, Dec, Jan, Feb
882
19.30%
March
272
5.94%
April, Oct
271
5.93%
May, June, July, Aug, Sept
46
1.00%
Annual total
• For gas we charge more units at the primary unit rate during the winter months to reflect the
fact that most customers use more gas in the winter. We believe this helps to make sure that all
our customers pay a fair share towards the fixed costs of supplying energy, and customers who
use very little gas in the summer months won’t be subsidised by other customers.
4572
If you were previously on our Tracker, Fixed Price 2009 or Sign Online 8 gas tariffs your primary rate gas units are allocated differently across the months – you can
find out more at npower.com/understandingprices or call Customer Service.
Here’s an example. If we send you a bill for the period 1 July to 30 September, we’ll aim to
charge a total of 138 primary rate units (46 units for each month). If no gas was used in one
of those months, but your gas consumption for the whole billing period was at least equal to
138 units in total, then we’ll charge 138 primary rate units on that bill. However, if you used
less than 138 units in that billing period, we won’t carry forward any uncharged primary rate
units to the next billing period.
Example
Step 1 – Work out how many units you’ve used
Subtract your previous meter reading from your current meter reading to work out the volume
of gas used. If you have an imperial meter that measures your gas in cubic feet (with 4 dials),
multiply this number by 2.83 to convert to cubic metres. If you have a metric meter (with
5 dials) there’s no need to do this.
Then multiply this number by the Calorific Value
and the Correction Factor, and then divide by
3.6 (round the answer to 1 decimal place) to give
you the total units (kWh) charged on the bill.
You can find the values for Calorific Value
and Correction Factor on your bills. These
figures can vary but are approximately:
Calorific Value
40.0
Correction Factor 1.02264
Let’s assume your previous meter reading is 48400 and your current meter reading is 48800
So the volume of gas used is:
48800 – 48400 = 400
Multiply by the Calorific Value:
400 x 40 = 16000
Multiply by the Correction Factor:
16000 x 1.02264 = 16362.24
Divide by 3.6:
16362.24 / 3.6 = 4545.1 units
So the amount of gas used is 4545.1 units
Step 2 - Work out the number of units to be charged at the primary
and secondary rate
The primary units will be allocated as shown in the table opposite. Any remaining units will be
charged at the secondary rate.
Let’s assume the three-month bill period is 15 March to 14 June
Work out the first month’s % at the primary rate
Take the number of days in the first month and subtract
the start day of the bill (March = 31 days)
31 - 15 = 16
Divide the answer by the number of days in the month:
16 / 31 = 0.516129
Multiply by the percentage for that month (as shown in
the table opposite ) and round to 2 decimal places:
0.516129 x 5.94 = 3.07%
So the first month’s proportion of the 4,572 units charged at the primary rate is 3.07%
Work out the middle months’ % at the primary rate
Use the full percentage for each full month (as shown in the table opposite)
Second month (April) = 5.93%
Third month (May) = 1.00%
5.93% + 1.00% = 6.93%
So the total for the middle months is 6.93%
Work out the last month’s % at the primary rate
Take the last day of the bill and divide by the number of
days in the last month (June = 30 days)
14 / 30=0.4666666
Multiply by the percentage for that month (as shown in
the table opposite) and round to 2 decimal places:
0.4666666 x 1.00% = 0.47%
So the last month’s proportion of the 4572 units charged at the primary rate is 0.47%
Now calculate the total percentage to be charged
at the primary rate for this bill
Add all percentages together:
3.07% + 6.93% + 0.47% = 10.47%
Multiply the total percentage by 4572 and round up
to a whole number, to get the units charged at the
primary rate:
10.47 / 100 x 4572 = 479
So the total number of units charged at the primary rate is 479
Step 3 - Work out the total bill
Let’s assume our prices are primary rate 8.5p per unit and secondary rate 3.5p per unit
Take the number of units at the primary rate
(from Step 2) and multiply by the primary rate,
then divide by 100 to convert into pounds and pence:
479 x 8.5 / 100 = £40.72
Take the total units (from Step 1) and subtract the
number of units charged at the primary rate (from Step 2)
to get the number of units charged at the secondary rate: 4545.1 – 479 = 4066.1
Take this number of units at the secondary rate and
multiply by the secondary rate, then divide by 100 to
convert into pounds and pence:
4066.1 x 3.5 / 100 = £142.31
Add these two together:
£40.72 + £142.31 = £183.03
Now multiply by 1.05 to add VAT at 5%:
£183.03 x 1.05 = £192.18
So the total bill including VAT is £192.18
Any questions?
If you still have any questions, why not try
looking for an answer on our website at
npower.com/faqs
Or you can call one of our specialist
Customer Service teams:
Direct Debit
0845 070 4851
Regular Payment Scheme
0845 070 4852
Quarterly cash/cheque
0845 070 4850
Please have your account number to hand when you call.
We’re here to help you 8am to 8pm Monday to Friday and 8am to 6pm Saturday.
Our top tips to help you be more energy
efficient and caring for the environment.
Tip 1
Tip 2
Tip 3
Getting your boiler
regularly serviced could
save you 10-15% of your
energy bills according to
the Carbon Trust. Learn
more about npower’s
boiler service and care
products at our website.
The Energy Saving Trust
says by turning down
your thermostat by just
1 degree could reduce your
heating bills by up to 10%.
Do your bit for the
environment, switch
to paperless billing
from npower.
For all this and more just visit npower.com
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npower is a registered trademark and the trading name of Npower Limited (Registered No. 3653277), Npower Gas Limited (Registered No. 2999919), Npower
Northern Limited (Registered No. 3432100) who also act as an agent for Npower Northern Supply Limited (Registered No. 2845740) for the supply of electricity,
Npower Yorkshire Limited (Registered No. 3937808) who also act as an agent for Npower Yorkshire Supply Limited (Registered No. 4212116) for the supply of
electricity. Registered in England and Wales. Registered Office: Windmill Hill Business Park, Whitehill Way, Swindon SN5 6PB.
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