Methods and assumptions

Formula-based tools

Each calculator page shows the method or formula it uses. The result depends on the values, units and assumptions entered by the visitor. A formula can be mathematically correct while still being unsuitable for a particular real-world decision.

Conversions

Unit converters use fixed relationships between the units shown. A conversion page identifies the units it uses. Where UK and US units differ, the unit label makes that distinction explicit.

Dates and times

Date tools use calendar values supplied in the browser. Unless a page explicitly states otherwise, they do not include local public holidays, payroll rules, business working patterns, time-zone changes or contractual cut-off times.

Financial tools

Financial tools do not use live rates, tax rules, lender charges, credit criteria, exchange rates, product terms, fees or personal circumstances. Enter the figures that apply to your situation and verify the result against relevant official or provider information.

Health and fitness tools

Health and fitness tools are general mathematical estimates. They do not provide medical advice, diagnosis, treatment advice or emergency guidance. Use professional medical support for health concerns or decisions.

Rounding

Where a result is displayed to a limited number of decimal places, the underlying calculation may include more precision. Rounding can matter for prices, materials, measurements and other sensitive quantities.