This is a tool that calculates the change in pressure or volume of a fixed mass of gas, if the temperature is held constant, using Boyle's Law.
The tool is multi-directional and, therefore, determines which volume or pressure needs to be calculated based on which data has been entered. The most typical scenario is to enter an initial pressure and volume and either the final pressure or volume, and calculate the other one. However, it is also possible to calculate either the initial pressure or volume from the entered final values. After one of the pressure or volume fields has been calculated, further data changes result in the re-calculation of the same field unless that field is itself changed or a different pressure or volume is cleared.
In more detail, the information that can be entered and/or calculated is:
Associated tool link: http://www.coggit.com/tools/boyles_law_calculator.html