You'll need to get replacement blades after 4 months of use as a rule (if you use it 2 times a week), which is also stated by the manufacturer itself. Of course, this is an individual matter that will ultimately depend on the actual frequency of use, type and hardness of the beard, etc. The blade should therefore last on average for 30 shaves. Always prefer the original Philips blades, which are marked QP230/50.