Determination of ignition spark duration

The method involves measuring the temporal gradient of the primary current flowing on the primary side and dividing the temporal gradient into a spark burning phase (23) and a subsequent free-wheeling phase of a high voltage-transmitter. The temporal gradient of the primary current is mapped in the spark burning phase by a function and in the free-wheeling phase by another function. Independent claims are also included for the following: (1) an ignition device with a measuring device; and (2) an internal combustion engine with a regulating device.