The front hull had 80 mm (3.1 in) of armour angled at 55 degrees from the vertical, welded but also interlocked with the side and bottom plates for strength. The combination of moderately thick and well-sloped armour meant that heavy Allied weapons, such as the Soviet 122 mm A-19, 100 mm BS-3 and US 90 mm M3,were needed to assure penetration of the upper glacis at normal combat ranges
The armour for the side hull and superstructure (the side sponsons) was much thinner at 40–50 mm (1.6–2.0 in). The thinner side armour was necessary to reduce the weight, but made the Panther vulnerable to hits from the side by all Allied tank and anti-tank guns. German tactical doctrine for the use of the Panther emphasized the importance of flank protection and 5 mm (0.20 in)-thick spaced armour or armoured skirts, known as Schürzen were added. Intended to provide protection for the lower side hull from Soviet anti-tank rifles such as the PTRS-41, the armour was fitted on the hull side. Zimmerit coating against magnetic mines started to be applied at the factory on late Ausf. D models beginning in September 1943,an order for field units to apply Zimmerit to older versions of the Panther was issued in November 1943. In September 1944, orders to stop all application of Zimmerit were issued, based on false rumours that hits on the Zimmerit had caused vehicle fires. Panther crews were aware of the weak side armour and made augmentations by hanging track links or spare roadwheels onto the turret and/or the hull sides
