It’s larger. As much as 6 times larger.

High definition video is certainly larger than standard definition video.

1080 format frame is 5.33 (perceived geometry) or 5.93 (resolving power) times larger than your old North American NTSCSD video.

720 format frame is 2.37 (perceived geometry) or 2.63 (resolving power) times larger than SD.

Imagine 6 TVs stacked in two rows of three TVs. That’s roughly how much 1080 format is larger than SD [Fig. 1].

Fig. 1. HD and SD Frame Size Comparison