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Tariff comparison calculator

Compare whole-bill costs for your current and proposed energy tariff.

Whole-bill tariff comparison

Three steps: your usage, your current tariff (pre-filled with the Ofgem price cap) and the new offer from the supplier's tariff information. Entered rates are compared as though they applied for the whole period; future variable rates are not predicted.

Single-rate tariffs only. Each tariff has one electricity unit rate. For day/night tariffs use the Economy 7 calculator; for time-of-use tariffs see EV tariffs or heat-pump tariffs.

  1. Step 1: Your usage

    Default: Ofgem typical use.
    Mains gas supply
    The gas standing charge applies even if you use no gas.
    Enter 0 if the meter is connected but unused.
    Sets your Ofgem region, so the cap rates match your area.

  2. Step 2: Your current tariff

    Ofgem price cap, October 2026 - December 2026, England, Scotland & Wales average, Direct Debit, including VAT.

    Electricity unit rate
    26.32p/kWh
    Electricity standing charge
    54.83p/day
    Gas unit rate
    7.97p/kWh
    Gas standing charge
    29.68p/day
    Change current tariff

  3. Step 3: The new offer

    Copy the rates from the supplier's tariff information label, for the same region and payment method.

    Exit fees, incentives and contract details
    Only paid if you leave a fixed deal early.
    From the new offer, counted once.
    Used for the period total and break-even.

Enter the new offer's rates in step 3 (unit rates and standing charges) to see your annual cost and saving.

Assumptions used
  • Annual cost = electricity usage cost + electricity standing charge + gas usage cost + gas standing charge. The gas standing charge is included whenever a gas supply is connected, even at zero use, and left out for an electricity-only home.
  • Standing charges use 365 days a year. Unit rates and standing charges include VAT when taken from the Ofgem cap.
  • Single-rate electricity only. Day/night and time-of-use rates are not modelled.
  • Both tariffs are compared at the entered rates for the whole comparison period. Variable rates can change each quarter.
  • The one-off credit is subtracted once, in the first year. The annual figures leave out the exit fee; the first-year saving includes both the credit and the exit fee.
  • Break-even is the number of months of lower bills needed before any credit, less the exit fee, turns into a net saving.
  • Default current rates: Ofgem price cap for October 2026 - December 2026, England, Scotland & Wales average, Direct Debit.