About 6 feet/1.8m. It plugs into the back of the mac - it isn't fixed in place - so you can replace it if you need to. Like a lot of Apple stuff, the socket is a standard connector type with some extra plastic moulding to make it all look smooth and pretty when plugged in - so you could plug in a regular IEC 3-pin power cable if you wanted (it just wouldn't look so nice).