How armour enters a cruiser's stability calculation

How much of a cruiser's armour arrangement was intended to help stability?

Armour was not principally fitted for stability, but designers included its effect in the ship's stability calculations.

Armour was not principally fitted to improve a cruiser's stability. Its presence nevertheless affected the ship's stability profile. Designers accounted for that effect while developing the whole ship. The armour's protective purpose and its contribution to the stability calculation were therefore separate considerations.