Methodology

See how each number was built.

A cost estimate is only useful when you can see its inputs. Our guides show where the figures came from, what the example assumes, and which part you need to replace with your own information.

Where the facts come from

We start with regulators, government departments, safety bodies, utilities, and established consumer organisations. Each guide lists its sources and access dates. If a rate, rule, or provider term may have changed, check the linked source before relying on it.

How examples are calculated

We state the household situation, units, time period, and inputs. For example, an appliance estimate should show its wattage, hours of use, unit rate, and number of days. A worked example is a way to test the method; it is not a forecast for every home.

When a guide changes

We update a guide when a source changes or a material error is reported. The page shows its latest update date. If you find a problem, send the page address and the evidence through the contact and corrections page.

What still needs checking

Location, property condition, usage, eligibility, tariffs, and provider terms can change the answer. For a legal, safety, insurance, or financial decision, use the current official source or qualified advice as well.