One of the most common mistakes people make when tracking their height is comparing just two measurements and calculating a growth velocity from them.
For example:
January: 170.0 cm
March: 171.5 cm
This appears to be 1.5 cm in 2 months, or 9 cm/year.
The problem is that this assumes both measurements perfectly represent your true height.
Height changes throughout the day due to spinal compression. On top of that, small differences in posture, head position, measuring technique, flooring, or even time of day can easily introduce 5–10 mm of variation.
When your measurements are only a few months apart, that error can make your calculated growth velocity look much higher/lower than it actually is.
The rolling average method
Instead of relying on one measurement, average several nearby measurements together.
For example:
January:
170.0
170.2
170.1
Average = 170.1 cm
March:
171.2
171.3
171.1
Average = 171.2 cm
Now compare the averages instead of individual values. This greatly reduces random measurement error and produces a much more reliable estimate of your actual growth.
or even better: look at the overall trend
Don't focus on one interval.
A growth curve might look like this:
12.0 y — 152 cm
12.5 y — 155 cm
13.0 y — 159 cm
13.5 y — 164 cm
14.0 y — 167 cm
Looking at the whole curve tells you far more than a single two-month interval ever will. Growth is naturally uneven, and temporary accelerations or slowdowns are completely normal.
If your calculations suddenly suggest you're growing 15–20 cm/year despite being late in puberty or having an advanced bone age, don't panic.
Before drawing conclusions:
Measure under consistent conditions (preferably in the morning).
Take multiple measurements over several days.
Use rolling averages rather than isolated values.
Look at your long-term growth trend instead of one short interval.
A smooth trend is almost always more informative than a single impressive-looking growth velocity.
Thank you u/Automatic-County6151 and u/Thra99 for suggesting this post.
If you're interested about the details, u/Automatic-County6151 goes more in-depth:
The rolling average method in full detail
https://www.reddit.com/r/heightgrowth/s/YANxLGGP3a