The Stihl 025 is a 42cc chainsaw. A cc is equal to 1 cubic centimeter or mL, so 42 x 3.5 = 162.5mL of gas for this particular cylinder size on the Stihl 025 Please keep in mind that there are many chainsaws out there with different machine sizes and volumes – it’s important that you check your owner’s manual for specifics if you’re looking to replace parts or buy new gas for whatever reason!