Methodology

Start with inputs you can check

A calculation is only as useful as its inputs. Each tool names the quantities and units it needs, and explains the assumptions that affect its result.

• Use current bill prices where personal rates are supported.
• Check equipment labels, measured use or the relevant quote.
• Keep the country, units and comparison period consistent.

Follow the calculation

Results show formulas with the values used in the estimate. Energy, unit prices, fixed charges, losses and other adjustments are separated where they apply.

For example, an appliance calculation converts watts into kilowatts, applies the time in use and then applies the electricity price. Other tools use the method appropriate to their question.

Check the sources and dates

Published defaults come from recorded official or manufacturer sources. Source links and checked dates help you identify the record behind a price, rule or equipment figure.

A checked date records when a source was checked; it does not guarantee that a price or rule is still current. If a required figure cannot be verified, it must not be published as a default.

Compare like with like

Use the same demand and time period when comparing options. Read whether a result includes taxes, standing charges, installation costs, maintenance or other costs.

Equipment performance, household use and the scope of a quote can materially change a comparison. The tool’s assumptions and limits belong alongside the figures.

Precision and incomplete edits

Calculations retain more precision internally than the displayed figures. Currency and intermediate values are rounded for readability, so displayed parts may not add up exactly.

After you calculate, valid edits can update the result. If an edit is incomplete or invalid, the last valid estimate is retained and labelled until the inputs are valid again.

Use estimates with judgement

Actual costs can differ because prices, weather, equipment performance and household use change. Worked examples illustrate a method; they are not a prediction of your bill.

There is no expert review. Check current sources and seek qualified advice before acting on a significant decision.