A big teddy in a small room
Start with the landing spot. A gift may make a wonderful entrance and still need somewhere to sit the next morning. Measure the chair, bedside corner, or open floor space you have in mind.
Next, look at the full product size. A 100 cm bear is about 39.4 inches in listed length; a 200 cm bear is about 78.7 inches. Those numbers describe very different gifts, even when the photos look similar.
Finally, think about moving day. If the recipient travels between home and campus, a more compact design may be easier to bring along. The right size is the one that works for their real room and routine.
