just a confusing question about height measuring.

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hey everybody i'm now on the LL.
right now i've lengthen 2.6cm.
my original height is 159cm (measured in many places and i'm pretty sure it's precise or 0.1cm error).
but today i measured my height: 160.5cm
i should be 161.6cm right now but i'm only 160.5.

so here is the question: does any LLER measure his/her height during the LL and find out it's lower than it should be? well, my posture is fine since my leg can stand pretty straight.

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similar method as yours. external one on tiebia.
i am wondering that the height right now is incorrect since the difference is 1cm. maybe i should measure my height after i fully complete the LL?

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i am sure that i measured my height at similar time.
so, is it possible that duck ass can result 1.2cm error?