Take, for example, this image of a crewman standing next to a T-72 versus Khamenei et al standing in roughly the same spot relative to the Zulfiqar. Compare the relative hull heights.
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I have estimated Zulfiqar dimensions before, but because of the low precision (on account of photo perspective), a broader sample size necessarily improves accuracy. Dimension estimates are based off a road wheel diamter of 66 cm.