Specimens break at the notched portions, as the impact stress is focused and concentrated in that section. For specimens undergoing the Charpy test, specimens can have either a V-shaped or U-shaped notch, with test specimens only having one notch in the middle.

Three notches can be applied to specimens undergoing the Izod test, which is suggested for a test that involves averaging within their methodology. In this test, the specimen is broken one after the other.