How is my Smart Dynamic bill calculated?

Your Smart Dynamic bill is based on your actual electricity use, measured every half hour by your smart meter. You can view your Smart Dynamic bills on your online account.

Here’s how it works, step by step.

1. We start with your half‑hourly usage

Your smart meter records how much electricity you use in each half‑hour period. You can see this detailed usage in the Cost and Usage Data (BDF), available to download from your online account. BDF stands for Billing Downloadable File. 

2. Each half hour is priced individually

For every half hour on your bill:

• Your electricity use (in kWh) is multiplied by the dynamic unit rate for that specific half hour
• This reflects the day‑ahead price, with built‑in price caps applied

We add up these half‑hourly amounts to get your total dynamic electricity cost for the billing period.

3. Your bill shows an average unit rate

Because prices change every half hour, we don’t show every individual price on your bill. You can see the full half‑hourly breakdown in your online account.

Instead, we show an average dynamic unit rate for the billing period. We calculate this by taking your total dynamic electricity cost and dividing it by your total electricity use (kWh).

You can still see the full detail of every half hour in your online account if you want to dig deeper.

See the example below, which shows how the average unit rate is calculated across six half‑hour periods.

Once we’ve calculated your total electricity usage and the total dynamic cost across all half‑hour periods, we divide the total cost by the total usage.

This results in an average unit rate of €0.1278 per kWh, which is 12.78 cent per kWh.

This is your average unit rate for the billing period, and it’s the rate that will appear on your bill. VAT is added after this.

4. Base unit rate and standing charge

Your total bill also includes:

• A base unit rate, applied to your half‑hourly usage
• A standing charge , which is a fixed daily cost and doesn’t depend on how much electricity you use

These are shown separately to give full transparency. 

5. Final bill total

Once we’ve added together:

• Dynamic electricity costs
• Base unit rate costs
• Standing charge

We then add the PSO levy and VAT to give your final bill total.

If you like to check the detail, your BDF shows all the information used to calculate your bill, including half‑hourly usage and prices.

Please note: prices shown in the BDF already include VAT, while on your bill VAT is added at the end. That’s why the figures may look slightly different, even though the total amount is correct.

For information on our current base rates and standing charge, see Our Tariffs Explained.