Measure the temperature change between the two points in time where the heat release is to be measured. This value is often called "Delta T" and is the difference of the final temperature minus the initial temperature. Confirm the temperature scale used to measure Delta T is correct. The temperature scale required is Kelvin.
Multiply the Delta T by the specific heat of the material being measured. For example, the specific heat of water is 4.18 J / K x g, read as "Joules per gram Kelvin."
Multiply the resulting product by the mass of the specimen being examined. This mass must be in grams. The resulting product will be the heat in Joules, as all other dimensions will cancel out, lost or gained, during the time period observed.