This chart provides the hard drive capacity required given the number of cameras you have and how many days of continuous footage you want to store and have access to . This is worked out using 24 hours of continuous storage per day using HD video streams.

  7 days  14 days 30 days 60 days  90 days
1 camera 105GB 210GB 450GB 900GB 1.35TB
2 cameras 210GB 420GB 900GB 1.8TB 2.7TB
3 cameras 315GB 630GB 1.35TB 2.7TB 4.05TB
4 cameras 420GB 840GB 1.8TB 3.6TB 5.4TB

 

If you want to store 24 hours of high definition (HD) video footage, then each camera will use 15GB of storage capacity per day.

 

This means that if you want to store approximately one month's worth of footage from 4 cameras, then the total capacity required is:

 

15GB*4(cameras)*30(days)=1800GB

 

So a 2TB hard drive is sufficient to store up to 1 month of HD video for 4 camera system.