It’s normally last up to 3-5 weeks. It’s may varies base on your diet, daily routine, cleaning habits and shedding cycle. Most of the eyelash extension place will recommend a 2 or 3 week fill for a fuller look that you like. We had a client came back on her 6 weeks and she still has 20% of the extension left as a result with out fill. Again, it is client to client.