Why gun count alone cannot determine warship size

How large must a cruiser be to carry a proposed battery of twelve large guns?

The battery is not enough information; speed, draft, machinery, fuel, protection, and mission equipment also determine the ship's size.

A specified gun battery leaves out the design variables needed to size a cruiser: speed, draft, engine type, endurance, and the other loads the ship must carry. Two hulls of similar size can mount different gun totals because one devotes more volume and displacement to fuel or another capability. Naval architecture therefore begins with a balanced requirement rather than scaling a hull directly from weapon caliber and barrel count.