Wear-time guides
How long does cologne last
Cologne has no universal wear time because the word can mean eau de cologne or simply fragrance in casual usage. Identify the exact product and formulation-style label before evaluating how long its scent remains enjoyable.
A HUME Fragrance buying guide

Resolve the meaning first
A product called Cologne is not necessarily described the same way as a traditional eau de cologne. Read the full label and maker information before making comparisons.
Observe the actual composition
A citrus-led opening may change noticeably while other impressions remain. Record the later character rather than equating the loss of initial brightness with total disappearance.
Use your intended occasion
Decide whether the fragrance remains suitable for the period you actually want to wear it. Duration alone does not decide whether you enjoy the scent or prefer the format.
Try this before you buy
Write what cologne means on the actual product label, then record the opening and later impression separately.