Check a billHow to calculate your electricity bill from a meter reading
If you want to challenge a bill calmly, learn the manual method once. The basic logic is simple: work out the kWh used, multiply by the unit rate, add standing charge for the billed days, then check whether anything else on the statement is an account adjustment rather than actual energy use.
The simple version
- Take the end reading and subtract the start reading.
- That gives you the usage figure the bill is trying to charge for.
- Multiply the usage by the unit rate in p/kWh and divide by 100 to get pounds.
- Multiply standing charge in p/day by billed days and divide by 100.
- Add the two subtotals together and then inspect any other lines separately.
If the bill uses multiple rates or multiple registers, split the calculation by each rate block rather than forcing everything into one number.
Related guides
What people often forget
- The bill may cover more or fewer days than the previous one.
- There may be two unit rates in one statement.
- Monthly payment changes are not the same as billed usage cost.
- Past credit, debt or refunds are separate from current energy consumption.
Official and reference sources
Frequently asked questions
Can I calculate the whole bill with one formula?
Only for a simple single-rate bill. More complex statements need separate rate blocks or register splits.
What if the bill still differs from my calculation?
Check whether the reading used was actual, whether there are multiple rates and whether the bill includes account adjustments.
Is this enough to prove the supplier is wrong?
It gives you a strong first-pass check, but you still need the reading evidence and the full statement details.