Armor thresholds

HE penetration

Here are some common armor thicknesses and the minimum HE shell diameters needed to penetrate them, according to the HE penetration formula. "Super" refers to the enhanced HE penetration of British battleships, German cruisers, and German battleships.

Armor thickness	Occurrences (non-exhaustive)	HE shell diameter needed to penetrate				Beneficiaries (non-exhaustive)
		Standard	IFHE	Super	Super IFHE
16 mm	Tier 3 battleship bow/stern Tier 6-7 battleship superstructure Most tier 6-7 cruiser bow/stern	99 mm	76 mm	66 mm	51 mm
19 mm	Tier 4-5 battleship bow/stern Tier 8-10 battleship superstructure Tier 8-10 destroyer plating	117 mm	88 mm	78 mm	59 mm	Some destroyers (100 mm - 114 mm)
25 mm	Tier 6-7 battleship bow/stern Some tier 8-10 cruiser bow/stern	153 mm	118 mm	102 mm	79 mm	Many light cruisers (152 mm) Most destroyers (120 mm - 150 mm)
27 mm	Some tier 8-10 cruiser bow/stern	165 mm	124 mm	110 mm	83 mm	Most light cruisers (152 mm, 155 mm) Some German secondaries (super 128 mm) Most destroyers (127 mm - 150 mm)
30 mm	Some tier 8-10 cruiser plating	183 mm	142 mm	122 mm	95 mm	Most light cruisers (152 mm, 155 mm, 180 mm) Some German secondaries (super 128 mm)
32 mm	Tier 8-10 battleship bow/stern	195 mm	148 mm	130 mm	99 mm	Most light cruisers (152 mm, 155 mm, 180 mm) Some German secondaries (super 128 mm)
50 mm	Khabarovsk belt Moskva plating Großer Kurfürst deck	303 mm	232 mm	202 mm	155 mm	Henri IV (240 mm)

• As can be seen, 152 mm and 155 mm guns, primarily found on light cruisers, are by far the biggest beneficiaries.
• It is also necessary for Akizuki to penetrate many important targets.
• Some other ships gain some benefit, but this is not generally considered worth the cost in skill points.

AP penetration

Armor thickness	AP shell diameter needed to overmatch	Occurrences (non-exhaustive)	Notes
10 mm	144 mm	Tier 4-5 cruiser superstructure Tier 4-5 destroyer plating	Will bounce most destroyer shells if sufficiently angled, but not most light cruiser shells.
13 mm	186 mm	Tier 4-5 battleship superstructure Most tier 6-7 cruiser superstructure	Will bounce light cruiser shells if sufficiently angled but not heavy cruiser shells (203 mm).
16 mm	229 mm	Tier 3 battleship bow/stern Tier 6-7 battleship superstructure Most tier 6-7 cruiser bow/stern Tier 6-7 destroyer plating	Will bounce almost all cruiser shells if sufficiently angled. Notable: Can bounce Moskva (220 mm) but not Henri IV (240 mm), Graf Spee or Scharnhorst (283 mm).
19 mm	272 mm	Tier 4-5 battleship bow/stern Tier 8-10 battleship superstructure Tier 8-10 destroyer plating	Will bounce up to 10-inch shells (254 mm) if sufficiently angled. Notable: Can bounce Henri IV (240 mm), but not Graf Spee, Scharnhorst (283 mm), Kronshtadt (305 mm).
25 mm	358 mm	Tier 6-7 battleship bow/stern Some tier 8-10 cruiser bow/stern	Will bounce up to 14-inch shells (356 mm) if sufficiently angled.
27 mm	387 mm	Some tier 8-10 cruiser bow/stern	Will bounce up to 15-inch shells (380 mm) if sufficiently angled.
30 mm	430 mm	Some tier 8-10 cruiser plating	At current only Republique (431mm), Conqueror with larger-caliber option (457 mm), Musashi and Yamato (460 mm) can overmatch.
32 mm	458 mm	Tier 8-10 battleship bow/stern	At current only Yamato and Musashi (both 460 mm) can overmatch.