As I remember, with calc_overhead = true, uT is showing the actual-net data traffic rate. The limits you set - do include the overhead. Any external tool that you use to measure the traffic, will show the total traffic, that equals to those limits you've set, and NOT to the actual rate uT displays. edit: As far as I can see - in this version the actual (external) rate measurement exceeds the limit we set in uT (at least for upload) . This should be investigated. ( Measured with - http://www.softpedia.com/get/Network-Tools/Bandwidth-Tools/NetMeter.shtml )