To use an online pressure conversion calculator, provide a measurement in the known unit, specify the unit to convert it to, and then press or click a button typically labeled "calculate" or "convert." In general, the process is similar on most modern hand-held calculators or when using a pressure conversion calculator app on a smartphone.
At OnlineConversion.com, click the Pressure link about midway down the main page to display a pressure calculator. Type the measurement in the known unit in the Convert What Quantity box, click the known unit in the From drop-down box, click the unit to convert to in the To drop-down box, and then click the Convert button to display the solution in the Result box.
At UnitConversion.org, click the Unit Converter tab near the top-right of the page, click the Pressure Conversion link in the list of common converters, and then click Switch to Compact Pressure Converter near the top of the page. Type the measurement in the known unit in the From drop-down box, click the unit to convert from on the list of units on the left, and then click the unit to convert to on the list on the right to display the result in the To and Result boxes.