A spark plug for an internal combustion engine, having an insulator including an insulator shoulder designed for mounting a tensioning nut or a housing and having a first outer diameter, an insulator head which is situated farther from the combustion chamber and adjoins the insulator shoulder, and which has a second outer diameter which is smaller than the first outer diameter, and a continuous cavity, a composition including a first contact composition, a second contact composition, and a composition resistor situated between the first contact composition and the second contact composition, a connecting pin which contacts the first contact composition, a center electrode which contacts the second contact composition, and a ground electrode. The connecting pin, the composition, and the center electrode are situated in the cavity, and the composition resistor has a third outer diameter, and a ratio of the third outer diameter to the second outer diameter is between 0.35 and 0.7.