Ergs per second to milliwatts conversion calculator shown above calculates how many milliwatts are in 'X' ergs per second (where 'X' is the number of ergs per second to convert to milliwatts). In order to convert a value from ergs per second to milliwatts (from erg/s to mW) just type the number of erg/s to be converted to mW and then click on the 'convert' button.