Calculate with your own figures
Use the calculator that matches the information on your bill. Each result is an illustration of the figures you enter, not a supplier statement.
Electricity cost
Estimate a usage cost from kWh and your own electricity rate.
Gas cost
Estimate a gas usage cost from billed kWh and a bill rate.
kWh cost
Turn kWh and a pence-per-kWh rate into a simple cost.
Energy bill
Explore usage, rates and standing charges for a period.
Economy 7
Compare peak and off-peak costs using your tariff figures.
Appliance running cost
Estimate an appliance cost from watts, hours and your rate.
Gas units to kWh
Convert meter volume using the factors shown on your bill.
Choose the tool that matches the evidence you have
Use a usage-and-rate calculator when you know billed kWh and the unit rate, the appliance tool when you know power or measured kWh, the whole-bill tool when dates and standing charges matter, and the Economy 7 tool for two-rate comparisons.
Seven useful starting points
Use the electricity and gas cost tools for fuel-specific checks; the kWh tool for the smallest rate calculation; the energy bill tool when standing charges matter; Economy 7 for two registers; the appliance tool for watts and hours; and the gas-units-to-kWh tool when your gas meter and bill use different units.
Prepare figures from your own statement
Keep the billing period, units, rate, standing charge and whether readings are actual or estimated. The tools do not fetch a live tariff and should not be treated as a supplier bill.
Read the calculation trail
Results show the inputs and method the tool used. If a required value is missing or invalid, the result should remain unavailable rather than silently becoming zero.
Use the result to choose the next question
A calculator can show whether your arithmetic is plausible, but it cannot decide why a supplier changed a Direct Debit or whether a tariff is available. If the result differs from a bill, compare the dates, reading type, rate, standing charge and account adjustments before assuming an error.
Ask the checker only after the free result
A calculator can answer the arithmetic without a conversation. If you need help interpreting a mismatch or deciding what evidence to gather next, use the non-personal assistant handoff after reviewing the result.