Hi, and thanks for reaching out! Our 60 day claim is based on robust testing by the Air Wick Research & Development team. Each Air Wick Scented Oil when used on the lowest setting for 24 hours per day, dispenses up to 60 days of our fragrance. The bottle may appear empty for the last few days, but the wick will still be saturated with fragrance which will evaporate into the room in the normal way. We hope this information helps! Sincerely, Your Air Wick Team!