The Thermal Stone, also known as Heat Stone, is a Survival item in Don't Starve. It requires an Alchemy Engine to prototype, and costs 10 Stone, 1 Pickaxe, and 3 Flint to craft. Its purpose is to delay body temperature change, preventing the player from Freezing in the Winter as well as Overheating in Summer (RoG).
A Thermal Stone absorbs heat from a fire, regardless of whether it is on the ground, in a Chest, or in the player's inventory. The size of the fire affects the maximum charge the stone can attain. A Red Hot Thermal Stone can emit enough light to ward off Charlie.
A Thermal Stone acts as a heat source with an internal temperature between -20° and +90°. With the thermal stone in the inventory, the player's own body will attempt to reach a temperature given by the formula:
T_b = (T_a + 2.1*T_h)/3.1
where T_b is the target body temperature, T_a is the ambient temperature, and T_h is the temperature of the thermal stone.
If the stone is on the ground instead, the target body temperature is instead given by:
T_b = (T_a + T_h)/2
which is simply the midpoint between the ambient temperature and the thermal stone's temperature.
The temperature of a heated thermal Stone drops at a rate determined by 120 insulation, which is 1 degree every 5 seconds. This insulation is only used for determining the stone's own temperature loss and does not affect the player.
The stage of the thermal stone is determined relative to the ambient temperature and each stage emits a fixed temperature:
|more than 30° below ambient temperature|
|between 30° and 10° below ambient temperature|
|between 10° below and 10° above ambient temperature|
|between 10° and 30° above ambient temperature|
|more than 30° above ambient temperature|
In all DLCs, cold Thermal Stones can be used in the Summer or Dry Season to prevent Overheating. A Thermal Stone can be cooled by placing it next to an Endothermic Fire, in an Ice Box, or in Snow Chester. Thermal Stones placed in Snow Chester will cool at half the rate that they would in an ice box.
In the Shipwrecked DLC, Thermal Stones are an ingredient for the Ice Maker 3000.
The Thermal Stone in Don't Starve Together has some differences from Singleplayer and its DLCs:
- Every time the Thermal Stone goes from Freezing White or Glowing Red to Gray, the Thermal Stone loses 12.5% of its durability. It can, however, be repaired with a Sewing Kit, one use of which will fully repair it.
- A level 5 or Glowing Red Thermal Stone can emit enough light to ward off Charlie.
- Thermal Stones stored in Snow Chester will cool at the same rate of an Ice Box. Blue and gray Thermal Stones can be given to the Antlion to appease it, delaying its rage by 2.98 days. When offered white, yellow or red Thermal Stones it will become enraged.
- The crafting recipe will accept pickaxes of any durability, so it is advised to use pickaxes that are at 3% durability to avoid wasting their use.
- In Winter, the Thermal Stone actually freezes the player at its coldest state, and during Summer/dry season hot Thermal Stones overheat the player. Chester, Packim Baggims or Hutch can be utilized to carry the cold/hot Thermal Stones, without affecting player temperature. Companions are immune to the effects of Freezing and Overheating.
- Having more than one Thermal Stone, one carried with the player, the other one kept charged (near a fire for warmth, or in an Ice Box for cool) allows quick switching, instead of waiting for a single one to charge.
- Keeping a thermal stone by a fire for purposes other than warming up is ill advised as it will use up the thermal stone's durability over time.
- This item was added in the Doorway to Adventure update.
- The Thermal Stone was renamed from Heat Stone to best fit its functionality in the Reign of Giants DLC, since it can also be used to cool the player.
- In the final release of the DLC, Where there's a Wilson..., the Thermal Stone received a new, cleaner asset for when it is at minimum temperature. Also in this update, the minimum temperature for the Thermal Stone was set to 25 in the Summer, solving the previous issue where holding a frozen Thermal Stone would cause freezing damage in the Summer.
- A Dropped Thermal Stone can be used to dry off a player with as much efficiency as a fire. As long as wetness is going down, the player can stand next to a thermal stone of any color to dry off quickly. This can help while using an Endothermic Fire, as it does not dry the player like a regular Fire.
- In the console edition of Don't Starve Together, Thermal Stones sometimes may not heat up, even when placed next to a fire.