This varies person-to-person based on (among other things) your skin / hair, preferences, and how well you care for your blades. Most people see between 5 and 8 shaves on a set of blades. Some folks go months, and others swap them every few shaves. Our suggestion is to push them as far as you can out of the gate to get a sense for how long they last for you, and swap them only when you feel they are dull and not shaving any longer. You may be surprised how long they last. And finally, different blades will last different lengths of time for folks. So feel free to experiment with different blade brands. Reach out for suggestions if you don't know where to start.