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How to calculate your electricity bill: formula and practical example

Calculating your electricity bill may seem complicated, but it involves adding up several items: the energy you consume, your contracted power, meter rental, taxes and any other charges or discounts.

Woman using a calculator next to a laptop to review her expenses.

If you want to know how to calculate how much you will pay for electricity, first have three figures to hand: the kWh consumed during the billing period, your contracted power and the price you pay for each item. You can find all of these in your contract or a previous bill.

How to calculate your electricity bill step by step

To estimate an electricity bill, follow these steps:

  1. Calculate the cost of the energy consumed.
  2. Calculate the cost of contracted power.
  3. Add meter rental, if applicable.
  4. Add any other items, services or discounts.
  5. Apply the applicable taxes.
  6. Check the final amount.

The simplified formula is:

Electricity bill = energy cost + contracted power cost + meter rental + other items + taxes

This calculation may vary depending on your tariff, whether you have a fixed price, time-of-use pricing, PVPC, self-consumption or additional services.

How to calculate the energy cost

The energy cost is the variable part of your bill. It depends on how much electricity you consumed during the billing period.

The formula is:

kWh consumed x price per kWh = energy cost

For example, if you consumed 250 kWh in one month and your energy price is €0.15/kWh:

250 kWh x €0.15/kWh = €37.50

If your tariff has several periods, such as peak, shoulder and off-peak, calculate each one separately:

Period

Consumption

Price

Cost

P1

60 kWh

€0,22 /kWh

€13,20

P2

90 kWh

€0,16 /kWh

€14,40

P3

100 kWh

€0,12 /kWh

€12,00

Total energy

250 kWh

 

€39,60

This lets you see not only how much you consume, but also which periods account for most of your costs.

How to calculate the cost of contracted power

Contracted power is the fixed part of your bill. You pay it even if you use no electricity, because it represents the maximum capacity you can use at the same time.

The usual formula is:

contracted power x power price x billed days = power cost

For example, if you have 4 kW of contracted power, a price of €0.10/kW/day and a 30-day bill:

4 kW x €0.10/kW/day x 30 days = €12

Some tariffs have two power periods. In that case, calculate each period separately and add the two amounts.

If you want to check whether you have more contracted power than you actually need and avoid overpaying for the fixed part of your bill, you can find out how to calculate and adjust it to suit your household’s needs.

Calculate how much contracted power you need

Complete example of an electricity bill calculation

Imagine a monthly bill with the following figures:

 Item

 Calculation

 Amount

 Energy consumed

 250 kWh x €0.15/kWh

 €37.50

 Contracted power

 4 kW x €0.10/kW/day x 30 days

 €12.00

 Meter rental

 Approximate monthly amount

 €1.00

 Other items

 No additional services

 €0.00

Subtotal

 

 €50.50

The relevant taxes must be added to this subtotal. That is why the final bill will be slightly higher than the initial result.

This example is for guidance, but it helps you understand how an electricity bill is calculated and which items have the greatest impact on the total.

How to find out how much you will pay for electricity

To estimate your electricity costs before receiving your bill, you can make a forecast based on your current consumption.

You need:

  • cumulative consumption in kWh
  • price per kWh
  • contracted power
  • number of days in the billing period
  • meter rental
  • taxes and other items

If you can access your customer area or consumption curve, check how many kWh you have used so far this month. Then multiply that consumption by your energy price and add the fixed contracted-power charge.

This calculation will not always be exact, but it helps you plan and spot when your consumption is higher than usual.

What can affect the final bill amount?

Although the basic calculation is straightforward, several factors can change the result:

  • higher-than-usual consumption 
  • price changes across time-of-use periods
  • excessively high contracted power
  • additional services
  • meter rental
  • taxes
  • compensation for surplus electricity if you have solar panels
  • discounts and promotions
  • adjustments to previous meter readings.

So, if your bill rises sharply one month, do not look only at total consumption. Also check whether the price per kWh has changed, whether an adjustment has been applied or whether new charges appear on the bill.

How to reduce your electricity bill

Calculating your bill also helps you make better decisions. Once you know which part accounts for the most, you can act.

If your energy cost is high, review your consumption habits, the appliances you use most and the times of day when you use the most electricity.

If the fixed contracted-power charge is high, you may have more power than you need. Adjusting it could help you pay less each month.

If you have a time-of-use tariff, shifting some electricity use to cheaper hours can reduce your bill without reducing the number of kWh consumed.

And if you have solar panels, reviewing your self-consumed electricity and compensation for surplus energy can help you better understand the actual savings from your installation.

If you would rather not keep track of calculations, prices or consumption periods, you can explore the different electricity tariffs and choose the one that best suits your usage. If you want more predictability in what you pay each month, a flat-rate tariff can help you maintain a stable monthly payment and manage your expenses.

Discover the flat-rate electricity tariff

Frequently asked questions about calculating your electricity bill

How do you calculate an electricity bill?
Add the cost of the energy consumed, contracted power, meter rental, other items and taxes.

How do you calculate electricity consumption on a bill?
Multiply the kWh consumed by the price per kWh. If you have several periods, calculate each one separately.

How can I calculate how much I will pay for electricity?
Estimate the amount using your cumulative consumption, tariff price, contracted power and number of billed days.

Which has a greater impact on the bill: energy or power?
It depends on the household. Energy costs vary with consumption; contracted power is fixed and paid every month.

Why does my final bill not exactly match my calculation?
Because taxes, meter rental, adjustments, discounts, additional services or compensation for surplus energy may apply.

Can I calculate my bill if I have solar panels?
Yes, but you must consider the energy you draw from the grid, the energy you consume directly from your panels and any applicable surplus compensation.

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