Why is the cost and usage graph on my online account different to my bill amount?

The graphs on your online account will not exactly match your bill, as it's intended as an indication of your cost and usage only. 

There are a few reasons why your bill will differ from the graphs:

• The usage on your online graph is summed and rounded daily, weekly and monthly, rather than for your billing period. This may result in small differences in total consumption between your graph and your bill.  
• If you're on a free time plan, usage on your free day (e.g. Saturday) is subject to a fair usage cap of 1200 kWh per year, or approximately 100 kWh per month.  This is pro-rated at a rate of 3.29kWh per day of the billing period. Usage above the cap will be charged at the day unit rate but won’t be reflected in your graph. 
• The online graph amount includes VAT and standing charges, but doesn't include PSO levy.