Calcs

media: 25fps 1080p 50Mbps
Real world gives about 80 minutes per 32GB card
If three cards, then 240 minutes storage
=4 hours shooting capacity

1TB drive
=1024GB
How many 32GB cards will fit onto a 1TB drive?
1024/32=32 cards
32 x 32GB cards=42 hours footage

50Mbps
=50x60x60Mb per hour
=(50x60x60)/8 MB per hour
=((50x60x60)/8)/1024 GB per hour
=22GB approx per hour
=> 32GB card should hold approx 87 minutes
Real world gives about 82 minutes