How to Use OrthoCalculator

OrthoCalculator combines a standard mathematical calculator on the left with unit, clinical, date, research-statistics and paediatric tools on the right.

Clinical safety: Check every input, unit, formula and result against your institution’s approved method. The website supports arithmetic and does not replace clinical judgement.

1. Standard calculator

Select Basic or Scientific.
Enter the expression using the number and operation keys.
Press the orange = key to display the result.
Use AC to clear, ⌫ to remove the last entry, and the memory keys when required.

2. Conversion and clinical tools

Choose a category in the first list, such as Conversions, Clinical, Dates, Statistics or Paediatric.
Select the required tool in the adjacent list. Use the search field to find a tool quickly.
Enter all requested values and confirm the displayed units.
For conversions, choose the source and destination units or use Reverse units.
Press the orange = button beneath the fields. The result and available formula details will appear below it.

3. BMI height entry

Select either centimetres or feet-and-inches. When feet-and-inches is selected, OrthoCalculator converts the height internally before calculating BMI.

4. Date calculations

Dates are displayed and entered as DD/MM/YYYY. You may type the date or use the calendar button. Confirm that the day and month have not been interchanged before calculating.

The follow-up calculator starts from today by default but permits another starting date.
The time-since-event tool calculates elapsed time from surgery, trauma or injury to the present date.
Paediatric exact age uses the selected examination date.

5. History and privacy

The History view stores calculation summaries locally in the current browser. Clear the history from that view when it is no longer required. Do not enter patient names, record numbers, contact details or identifiable clinical narratives.

6. Light and dark modes

Use the theme button in the header to switch the page background. The selected appearance may be remembered by your browser.

Good practice: Record the source measurements and units separately, independently verify clinically important calculations, and document the approved formula used.