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

There are a few reasons why your bill may differ from the graphs, see below. 

The graphs in your online account are designed to give you an indication of your energy usage and cost. They won’t always match your bill exactly, and this is expected.
There are a few reasons why:

1. Graphs use calendar dates, not your billing period

The online graphs show usage by day, week, month or year, while your bill covers your billing period.
For example: If your billing period runs from the 9th to the 8th of the following month, the Monthly graph still shows usage from the 1st to the last day of the calendar month, so totals will differ.
 

2. Total cost view vs billing statement

The Total cost shown online is an estimate for the selected calendar period, while your bill includes all charges for your full billing cycle.
 

3. Difference between graph and table view

The graph gives a visual overview of usage trends, while the table view shows daily values.
Because neither follows your exact billing cycle dates, the totals may not align with your bill.
 

4. Free Time plan fair usage cap

If you’re on a Free Time plan, usage on your free day is capped at:

  • 1,200 kWh per year, or
  • approx. 100 kWh per month, pro-rated at 3.29 kWh per day

Any usage above this cap is charged at your normal day rate, but this extra usage does not appear in the graph, which can make your bill higher than what you see online.

5. VAT, standing charges and PSO levy

  • The graph includes VAT and standing charges
  • It does not include the PSO levy
    Your bill reflects all charges together.

6. BGE vs ESB Networks time stamp differences

There is a small difference in how smart meter intervals are displayed:

  • Bord Gáis Energy shows the start time of each half-hour interval.
  • ESBN shows the end time of each half-hour interval.

Example:
If ESB Networks shows 12:00am, this represents 11:30pm – 12:00am,
but BGE will show 11:30pm for the same interval.

This can sometimes shift usage by one calendar day between platforms.

Please note:

  • These differences are expected and do not indicate an issue with your meter or your bill.
  • The online graphs provide a helpful guide to your usage, while your bill is calculated using your actual billing periodand your price plan.