The amount of time a DVR will record is based on the size of the DVRs hard drive, the number of cameras recording and the frames per second. Our stand alone DVRs use 3.4 GB per camera per day. A 4 camera stand alone DVR with a 250 GB hard drive will record for 18 days. An 8 camera stand alone DVR with a 250 GB hard drive will record for 9 days. A 16 camera stand alone DVR with a 500 GB hard drive will record for 9 days.