Hammers can break down any player-made Structures and most naturally occurring Structures such as Pig Houses, yielding at least 50% of the materials used to create the Structure in most cases.
If the player strikes a container such as a Chest or Crock Pot, all items within will fly out but remain undamaged. It also can be used on an Ancient Pseudoscience Station and Ornate Chest, both of which are found in the Ruins, to make random effects and objects appear.
Bones can be hammered for Bone Shards, and hammering a Merm Head, a Pig Head, or a Wildbore Head during a Full Moon will yield Nightmare Fuel, as well as their usual items. The Hammer can also be used to "whack" Moleworms, which will stun them.
The Hammer can be used to break down structures by equipping it then right-clicking a structure. After the first right click, left mouse button or space bar can be held down to continue hammering until the structure breaks.
The Hammer can be used as a weapon, dealing 17 damage per strike. It has 75 uses, meaning each use will reduce 1.33% of its durability, whether it was used as a weapon or to deconstruct objects.
Using the Hammer on a Structure that has "uses" (e.g. the Tent) may return less than 50% of the materials used to craft it, based on how many times the Structure has been used. For structures that have usage, the amount returned for each type of ingredient is:
amount_returned = original_amount * percent_uses_left * 0.5
Hammering a structure will always yield at least one of each of the crafting materials, with the exception of Walls, which drop their main component instead. If the main component of the Wall is a Refined item, its base components are dropped instead. For example, a Sign which requires 1 Boards to craft will drop 1 Boards when hammered, a Hay Wall crafted from Cut Grass and Twigs will only drop Cut Grass, and a Wood Wall crafted from Boards and Rope will only drop Logs. Light Tab Structures will drop Ashes in addition to their components.
- The Hammer used to cost 30 Science Points to craft, and it used to have a value of 1-10 Science Points depending on its durability when used on a Science Machine.
- Before the Caves update, the Hammer was used with a left-click. It was changed to right-click so fewer accidents would happen, such as hammering Chests.
- A wooden Hammer is the icon used for the Structures Tab.
- Sometimes when hammering certain Structures, the resources will be shot out of the structure instead of being dropped normally.
- In the Reign of Giants DLC, it's possible to find a Hammer Blueprint, which cannot be learned by the player as the recipe for the Hammer is always available.