Irish Calculators
Everyday money

Electricity and Gas Cost Calculator

Calculate energy spending from known kWh, meter readings or appliance power and hours. Use VAT-inclusive tariffs and the gas conversion factor on your bill; current supplier prices are not retrieved.

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Your numbers

kWh
Use the actual billed conversion factor for your meter units. 11.2 is illustrative, not a universal gas conversion.
W
hours
€/kWh
€/day
€
Enter applicable levies and other known charges, including any VAT.
€
Your figures stay on this device.

How the calculation works

Energy can be entered directly as kWh or calculated from meter readings or appliance operation. The selected mode determines whether the result represents a bill including fixed charges or the incremental energy cost of using an appliance.

Appliance kWh = watts × hours/day × days × quantity ÷ 1,000. Electricity-meter kWh = latest − previous reading. Gas kWh = meter difference × the conversion factor shown on your bill. Bill = kWh × rate + daily standing charge × days + other charges − credits.

  1. Calculate energy consumed

    Direct mode uses supplied kWh; electricity meters use the reading difference. Gas multiplies the difference by its conversion factor, while appliance mode multiplies power, hours, days and quantity.

  2. Apply the unit tariff

    Multiply energy by the price per kWh. Appliance watts are converted to kilowatts so hours produce kWh rather than watt-hours.

  3. Reconcile bill adjustments

    Where applicable, add standing charges for the billed days and known extra charges, then deduct credits. Appliance results remain focused on usage rather than the whole household bill.

Worked example: Typical bill

Sample inputs demonstrate the method. They are not a forecast or product offer.

The first example prices 200 kWh at 0.30, giving 60 of energy cost. A daily standing charge of 0.50 over thirty days adds 15, producing an estimated bill of 75.

Starting information
Known electricity or gas energy (kWh)
Energy used (kWh)
200
VAT-inclusive unit rate (€/kWh)
0.3
VAT-inclusive standing charge (€/day)
0.5
Number of days
30
Other charges for this bill (€)
0
Bill credit or discount (€)
0

Expected result

Estimated bill
€75.00
Worked example: Credit

Sample inputs demonstrate the method. They are not a forecast or product offer.

Starting information
Known electricity or gas energy (kWh)
Energy used (kWh)
100
VAT-inclusive unit rate (€/kWh)
0.25
VAT-inclusive standing charge (€/day)
0
Number of days
30
Other charges for this bill (€)
0
Bill credit or discount (€)
10

Expected result

Estimated bill
€15.00

Understanding your result

An estimated bill can differ from a supplier statement if rates change within the period, readings are estimated or adjustments are omitted. Split materially different tariff periods before combining their amounts.

A device's rated power is not necessarily its average consumption. Cycling, standby behaviour and usage patterns must be reflected in the power or operating-time assumptions supplied.

Questions you might have

What does this electricity & energy cost calculator include?

Estimate an electricity bill or appliance running cost from kWh, meter readings or watts and operating hours, with the tariff you actually pay.

Which assumptions should I check?

Use VAT-inclusive tariffs. Gas volume-to-energy factors depend on meter units and the billed conversion; copy the applicable factor from your bill. Appliance mode excludes fixed household charges. No live tariff comparison, supplier login or automatic meter-file import is provided.

Choosing the right inputs

Starting information
Choose the data you actually have. Gas mode needs billed volume conversion; appliance mode uses power and running time rather than meter readings.
VAT-inclusive unit rate
Enter a VAT-inclusive price per kWh. This calculation does not add a separate tax layer or retrieve a supplier tariff.
kWh per meter unit from your bill
For gas readings, copy the factor applicable to the meter units from the bill. The illustrative factor is not universal.
VAT-inclusive standing charge
Enter a daily VAT-inclusive standing charge for bill modes. Appliance mode deliberately excludes fixed household charges.

Common mistakes to avoid

  • Do not apply VAT again to already VAT-inclusive tariffs.
  • Do not multiply gas volume by a factor meant for different meter units.

Assumptions to check

  • Use VAT-inclusive tariffs. Gas volume-to-energy factors depend on meter units and the billed conversion; copy the applicable factor from your bill. Appliance mode excludes fixed household charges. No live tariff comparison, supplier login or automatic meter-file import is provided.

Sources and method

Read our calculation and testing approach.