diff --git a/__DEFINES/materials.dm b/__DEFINES/materials.dm
index 78196c0b47c..d523723a731 100644
--- a/__DEFINES/materials.dm
+++ b/__DEFINES/materials.dm
@@ -80,3 +80,4 @@
 #define CC_PER_SHEET_MOLITZ      CC_PER_SHEET_METAL
 #define CC_PER_SHEET_GINGERBREAD CC_PER_SHEET_METAL
 
+#define CC_PER_U 10 //How many cc per 1 u of reagent in eg. a glass of water or a human's bloodstream.
diff --git a/__DEFINES/reagents.dm b/__DEFINES/reagents.dm
index 395d98d2793..69d4c45f955 100644
--- a/__DEFINES/reagents.dm
+++ b/__DEFINES/reagents.dm
@@ -522,7 +522,7 @@
 #define TEMPERATURE_WELDER 3480
 #define TEMPERATURE_PLASMA 4500
 #define TEMPERATURE_ETHANOL (T0C+1560)
-#define HEAT_TRANSFER_MULTIPLIER 7 //Multiplies the numbers above when heating a reagent container. A truly magical number.
+#define HEAT_TRANSFER_MULTIPLIER 7 //Multiplies the numbers above when heating a reagent container. A truly magical number. Not currently used anywhere due to a bug with reagent heating being fixed.
 
 // By defining the effect multiplier this way, it'll exactly adjust
 // all effects according to how they originally were with the 0.4 metabolism
diff --git a/code/modules/reagents/Chemistry-Holder.dm b/code/modules/reagents/Chemistry-Holder.dm
index 3e056508559..6e4dd9b57cf 100644
--- a/code/modules/reagents/Chemistry-Holder.dm
+++ b/code/modules/reagents/Chemistry-Holder.dm
@@ -606,6 +606,16 @@ trans_to_atmos(var/datum/gas_mixture/target, var/amount=1, var/multiplier=1, var
 		for(var/datum/reagent/R in reagent_list)
 			R.reaction_dropper_obj(A, R.volume+volume_modifier)
 
+/datum/reagents/proc/get_equalized_temperature(temperature_A, thermalmass_A, temperature_B, thermalmass_B)
+	//Gets the equalized temperature of two thermal masses
+	if(temperature_A == temperature_B)
+		return temperature_A
+	if(thermalmass_A + thermalmass_B)
+		return ((temperature_A * thermalmass_A) + (temperature_B * thermalmass_B)) / (thermalmass_A + thermalmass_B)
+	else
+		warning("[usr] tried to equalize the temperature of a thermally-massless mixture.")
+		return T0C+20 //Sanity but this shouldn't happen.
+
 /datum/reagents/proc/add_reagent(var/reagent, var/amount, var/list/data=null, var/reagtemp = T0C+20)
 	if(!my_atom)
 		return 0
@@ -616,9 +626,12 @@ trans_to_atmos(var/datum/gas_mixture/target, var/amount=1, var/multiplier=1, var
 	update_total()
 	if(total_volume + amount > maximum_volume)
 		amount = (maximum_volume - total_volume) //Doesnt fit in. Make it disappear. Shouldn't happen. Will happen.
-	chem_temp = round(((amount * reagtemp) + (total_volume * chem_temp)) / (total_volume + amount)) //equalize with new chems
 	for (var/datum/reagent/R in reagent_list)
 		if (R.id == reagent)
+
+			//Equalize temperatures
+			chem_temp = get_equalized_temperature(chem_temp, get_thermal_mass(), reagtemp, amount * R.density * R.specheatcap * CC_PER_U)
+
 			R.volume += amount
 			update_total()
 			my_atom.on_reagent_change()
@@ -641,6 +654,10 @@ trans_to_atmos(var/datum/gas_mixture/target, var/amount=1, var/multiplier=1, var
 	if(D)
 
 		var/datum/reagent/R = new D.type()
+
+		//Equalize temperatures
+		chem_temp = get_equalized_temperature(chem_temp, get_thermal_mass(), reagtemp, amount * R.density * R.specheatcap * CC_PER_U)
+
 		reagent_list += R
 		R.holder = src
 		R.volume = amount
@@ -901,25 +918,18 @@ trans_to_atmos(var/datum/gas_mixture/target, var/amount=1, var/multiplier=1, var
 /datum/reagents/proc/is_full()
 	return total_volume >= maximum_volume
 
-/datum/reagents/proc/get_heatcapacity()
-	var/heat_capacity = 0
-
-	if(reagent_list.len)
-		for(var/datum/reagent/R in reagent_list)
-			heat_capacity += R.volume*R.specheatcap
-
-	return heat_capacity
-
-/datum/reagents/proc/get_overall_mass()
+/datum/reagents/proc/get_overall_mass() //currently unused
 	//M = DV
-
 	var/overall_mass = 0
+	for(var/datum/reagent/R in reagent_list)
+		overall_mass += R.density * R.volume
+	return overall_mass * CC_PER_U
 
-	if(reagent_list.len)
-		for(var/datum/reagent/R in reagent_list)
-			overall_mass += R.density*R.volume
-
-	return overall_mass
+/datum/reagents/proc/get_thermal_mass()
+	var/total_thermal_mass = 0
+	for(var/datum/reagent/R in reagent_list)
+		total_thermal_mass += R.volume * R.density * R.specheatcap
+	return total_thermal_mass * CC_PER_U
 
 /datum/reagents/proc/heating(var/power_transfer, var/received_temperature)
 	/*
@@ -931,10 +941,8 @@ trans_to_atmos(var/datum/gas_mixture/target, var/amount=1, var/multiplier=1, var
 	*/
 	if(received_temperature == chem_temp || !total_volume || !reagent_list.len)
 		return
-	var/heat_capacity = get_heatcapacity()
 	var/energy = power_transfer
-	var/mass = get_overall_mass()
-	var/temp_change = (energy / (mass * heat_capacity))* HEAT_TRANSFER_MULTIPLIER
+	var/temp_change = (energy / (get_thermal_mass()))
 	if(power_transfer > 0)
 		chem_temp = min(chem_temp + temp_change, received_temperature)
 	else