Brief introduction - Following an impulsive heating event, a coronal loop will cool mainly by conductive and radiative losses. Cargill (ApJ, 422; 1994) showed that with some simple assumptions order of magnitude cooling times can be made--that ignore loop dynamics, such as the response of chromospheric heating due to a downward heat flux. which results in increasing density in the loop. The JavaScript model below is based on the Cargill 0D model and can be used for a quick estimate.
For more details please see the referenced text, and note that more up to date radiative phase functions should be used.
An adaption of the Enthalpy-Based Thermal Evolution of Loops (EBTEL) model (Klimchuk et al. 2008, ApJ, 682:1351-1362; Cargill et al. 2012A, ApJ, 752:161; Cargill et al. 2012B, ApJ, 758:5) will be scripted in the future.