Energy Tariff and Bill Checker

Check if a new energy tariff is cheaper for your usage, find the break-even kWh and exit fee payback, or see exactly why your bill went up.

Reviewed by Dany, RightSums team · Updated

Runs in your browser. Free, no sign-up.

home-energy · Daily life · UK & US

Compare two gas and electricity tariffs using your own kWh, or check why your latest bill is higher than the last one. For a comparison, enter each tariff's unit rate and standing charge (or a US fixed monthly charge), any exit fee and optional Economy 7 or time-of-use rates. You get the annual and monthly cost of each, the break-even usage where they cost the same, the winner at low, medium and high use and the months an exit fee takes to recover. For a bill check, enter both bills' kWh, rates, days, VAT and credits. The change is split into usage, unit rate, standing charge, days, tax and credits, adding up to the penny. UK defaults are the Ofgem price cap from 1 October 2026; US defaults are EIA averages.

Accepted inputs

  • Mode: compare two tariffs, or explain a bill change
  • Electricity unit rate in p/kWh or ¢/kWh for each tariff
  • Standing charge in p a day (UK) or fixed customer charge in $ a month (US)
  • Optional gas unit rate and standing charge (UK)
  • Optional peak and off-peak rates with the share used off-peak
  • Exit fee for leaving the current tariff
  • Usage in kWh a year or kWh a month
  • For each bill: kWh used, unit rate, standing charge, days, VAT or tax % and credits

Outputs

  • Annual and monthly cost of each tariff and the difference
  • Break-even usage in kWh for electricity and gas, with the working
  • Cheaper tariff at low, medium and high usage
  • Exit fee payback in months and net first-year saving
  • Bill change split into usage, unit rate, standing charge, days, tax and credits
  • Cost per day for each bill and tips based on your figures

How to use the Energy Tariff and Bill Checker

  1. Choose Compare two tariffs to test a new deal, or Why did my bill go up to compare two bills you already have.
  2. For a comparison, enter each tariff's unit rate and standing charge, any exit fee and your usage, which starts at Ofgem's typical 2,500 kWh of electricity and 9,500 kWh of gas a year.
  3. For a bill check, copy the kWh, unit rate, standing charge, days, VAT and credits from both bills, using the rates before VAT as they appear on the bill.
  4. Read the annual costs, break-even usage and exit fee payback, or the table that splits the bill change into its causes with the sum shown line by line.

Frequently asked questions

How do I know if a new energy tariff is cheaper for me?

Compare both tariffs at your own annual kWh, not a typical figure. A tariff at 24.50p/kWh and 62p a day beats the Ofgem cap from 1 October 2026 (26.32p and 54.83p) only above 1,438 kWh of electricity a year: (62 − 54.83) × 365 ÷ (26.32 − 24.50) = 1,438 kWh. Below that, the cap is cheaper because of its lower standing charge.

Why has my electricity bill gone up when my rates barely changed?

Usually because you used more energy or the bill covers more days. A September bill of 180 kWh over 30 days at the July cap was £64.16; an October bill of 210 kWh over 31 days was £72.27. Of the £8.11 rise, £7.83 came from extra usage, £3.20 from the unit rate, £0.69 from standing charges and days, and the VAT cut took off £3.61.

What is the energy price cap from 1 October 2026?

According to Ofgem, the Direct Debit average for England, Scotland and Wales from 1 October to 31 December 2026 is 26.32p/kWh and 54.83p a day for electricity, and 7.97p/kWh and 29.68p a day for gas. Ofgem says there is no VAT on domestic electricity from 1 October 2026 to 31 March 2027; gas keeps 5% VAT. Rates vary by region and payment method.

Is it worth paying an exit fee to switch energy tariff?

Only if the monthly saving repays the fee before the new deal ends. Moving from the October 2026 cap to a tariff saving £44.56 a year at typical dual fuel use takes 13.5 months to recover a £50 exit fee, so you lose £5.44 in the first year. Ofgem's rules stop suppliers charging exit fees in the last 49 days of a fixed term contract.

How much electricity and gas does an average home use?

Ofgem's typical domestic consumption values from 1 July 2026 are 1,600, 2,500 and 3,800 kWh of electricity a year for low, medium and high use on a single-rate meter, and 6,000, 9,500 and 14,000 kWh of gas. In the US, the EIA puts the 2024 average at 863 kWh of electricity a month, from 495 kWh in Hawaii to 1,202 kWh in Louisiana.

Sources

The rates and rules in this tool come from:

Guides that use this tool

Terms explained

  • Economy 7: Economy 7 is an electricity tariff with seven cheaper off-peak hours, usually overnight, and a dearer daytime rate; Ofgem assumes 42% of use falls off-peak.
  • Typical domestic consumption values (TDCVs): Typical domestic consumption values are Ofgem's yearly usage figures for a typical home, 2,500 kWh electricity and 9,500 kWh gas from 1 July 2026.

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