Have you ever wondered why your handmade set of platemail where each part has an AR value of "40" only gives you an overall armor rating of "36"? Well, here is the answer.
Sphere follows OSI's armor rating system. That means, that each armor part will show you an AR value what it will give you if you wear a complete set of armor where each part has this AR value. Depending on what body parts a selected armor part is covering it adds a procentual share to the overall armor.
Furthermore, armor pieces theoretically can be stacked. So a platemail chest covers chest and back, and a cloak covers the chest. But that does not mean that your back now is double protected: Like on OSI, Sphere only uses the covering part with the highest AR property. Therefore, if you wear a chain tunic under your plate, id adds to weight, but not to your character's AR.
Body parts and Percents
15 percent from ARMOR_HEAD
7 percent from ARMOR_NECK
5 percent from ARMOR_BACK
25 percent from ARMOR_CHEST
14 percent from ARMOR_ARMS
7 percent from ARMOR_HANDS
22 percent from ARMOR_LEGS
5 percent from ARMOR_FEET
What layer covers what?
LAYER_HELM gives ARMOR_HEAD
LAYER_COLLAR gives ARMOR_NECK
LAYER_SHIRT, LAYER_CHEST, LAYER_TUNIC, LAYER_CAPE, LAYER_ROBE gives ARMOR_BACK
LAYER_SHIRT, LAYER_CHEST, LAYER_TUNIC, LAYER_ROBE gives ARMOR_CHEST
LAYER_ARMS, LAYER_CAPE, LAYER_ROBE gives ARMOR_ARMS
LAYER_GLOVES gives ARMOR_HANDS
LAYER_PANTS, LAYER_SKIRT, LAYER_HALF_APRON, LAYER_ROBE, LAYER_LEGS gives ARMOR_LEGS
LAYER_SHOES, LAYER_LEGS gives ARMOR_FEET
Or, if you're preferring it the other way around:
A helmet, hat ect. will only cover the head, thus adding 10 percent to the total AR.
A gorget, but also a necklace will cover the neck, adding 5 percent to total AR.
A shirt (LAYER_SHIRT) can cover the back and the chest, adding up to 40 percent of total AR.
Items on LAYER_CHEST and LAYER_TUNIC behave like LAYER_SHIRT.
A cape may cover the back and the arms, adding up to 20 percent to total AR.
A robe may cover back, chest, arms and legs, adding up to 70 percent to total AR.
Armwear (LAYER_ARMS) only covers the arms, thus adding 10 percent to total AR.
Gloves and gauntlets are covering the hands, adding 10 percent.
LAYER_PANTS, LAYER_SKIRT, LAYER_HALF_APRON are covering the legs (20 percent of total AR).
LAYER_LEGS (like plate legs) and LAYER_SHOES are covering the feet (5 percent of total AR)
Do not forget that multiple coverings will _not_ stack; only the item with the highest AR property will be taken into account!
If you prefer it all in a combined table: