The number of possible sockets on equipment is based on the item level as well as the type of the equipment being used.
The number of sockets can be changed by Jeweller’s Orb reforging, using the Crafting Bench in your hideout, or an Orb of Binding. Corrupted items can only be changed through the Crafting Bench and need an equivalent amount of Vaal Orb as the usual cost of Jeweller’s Orb, Chromatic Orb and Orb of Fusing to change sockets on any corrupted item, or via the use of Tainted Jeweller’s Orb, Tainted Chromatic Orb, and Tainted Orb of Fusing.
Maximum number of sockets by equipment type
Most Belts, amulets, rings and quivers do not have sockets. Exceptions are Unset Ring, Unset Amulet, Black Maw Talisman, Stygian Vise, Ornate Quiver, and Mechanical Belt.
One-handed weapons and shields can only have up to 3 sockets max
Boots, helmets and gloves can have up to 4 sockets
Body armours and Two-handed weapons can have up to 6 sockets
Non-unique equipment can have up to 1 Abyssal Socket, with the appropriate modifier on the item.
Some items have exceptions to these rules, typically due to special modifiers or low-level base types with a different inventory size.
Item level
Number of sockets
Minimum ilvl
Weight (6S & 3S)
Weight (4S)
First vendor availability
1
1
50
100
Act 1
2
1
120
90
Act 1
3
2
100
80
Act 1
4
25
30
30
Act 3
5
35
5
N/A
Act 4
6
50
1
N/A
Act 6/7
The item level item is generally applicable, but note that there are a few cases where these restrictions may be overridden or ignored:
Hillock, upon death, always drops a specific weapon with three unlinked RBG sockets, which is dependent on your class (identical basetype to starter weapon) (technically, this still respects the socket limit.)
Unique items that override the socket mechanics, such as Tabula Rasa or Skin of the Loyal, which always have 6 (linked) sockets regardless of item level. Altering the socket count via crafting bench and attempting to use Jeweller’s Orbs will cause it to respect item level again.
Items from strongboxes with of Complexity affix can exceed the item level limit.
A specific number of sockets can be crafted on an item using the Crafting Bench ignoring item level restrictions
Monster modifiers that cause items to drop with maximum sockets appear to ignore item level.
Certain heist enchantments can modify the number of sockets on an item when rolling with a Tailoring Orb or Tempering Orb.