A method for determining the size of a crack (26) in a workpiece (20), in particular the depth of a crack (26) in this workpiece (20), by means of the ultrasound - pulse - method and with the following steps: a workpiece (20) has a front surface (22) and a rear surface (24), in the work piece (20), there is a crack (26), of the of the rear surface (24), is an angle probe (28) on the front surface (22) is placed, it emits ultrasonic pulses at an angle alpha in the workpiece (20) and receives echo signals of these pulses, the angle probe (28), at least on the one hand by means of the crack (26) is moved, so that the radiation lobe (46) of the angle beam (28) of the crack completely sweeps over (26), the received echo signals are digitized and stored in a memory (40) as pairs of values stored by means of the echo signal transit time, the stored value pairs form an upwardly by an envelope curve (48) limited amount, from the width of the envelope curve (48) in the case of a predetermined part of amplitude and from the maximum amplitude of the envelope curve (48), the dimension of the crack (26) is determined.
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