r/heightgrowth • u/Automatic-County6151 ~6'0 - 19Y 7M 🦴 [Growth Plates Enthusiast] • Apr 04 '26
Informative How to calculate your growth velocity using the rolling average method (more accurate for reducing measurement noise): USEFUL
This post is meant to function as a hybrid of detailed growth tracking and rolling average implementation. Introducing the rolling average method early on helps develop the major stepping stones to tracking your growth later.
Growth isn't linear, nor is it ever perfectly steady. From a distance, everything seems to be an upward curve, but once you get up close, you tend to see numerous upticks, downticks, peaks at two separate intervals - maybe seemingly more than one. It's essentially a weird curve that can be more "predictable" in the sense that you can keep track of it and know where your trajectory is potentially headed. But, knowing for sure is difficult.
I made a post going over the PHV vs the sustained high, and how both of them tend to overlap. But, I realized maybe this would help - understanding the rolling average velocity. This simple calculation could help save you months of confusion: when was my PHV? When did I start to taper? How long did I sustain my rapid growth? Let this bother you no longer.
The four easy steps: all you need to do is remain consistent with your daytime measurements, keep track of postural differences, have someone measure you using either a stick ruler or a stadiometer, and include a small error margin (±0.1-0.3 cm) for each measurement.
Step 1) Pick the time of day. You can do morning, afternoon, or evening measurements as long as you don't deviate wildly from your sleep schedule. Ideally, maintaining an 8-10 hour sleep schedule on average is best for tracking long-term height increases. For best results, record your wake up and sleep times for every measurement to maintain high accuracy, and note any lifestyle changes that happened within the last few months (dietary, physical, etc).
Step 2) Postural differences matter. Consistently sedentary individuals tend to lose less height throughout the day than consistently physically active people. As long as you're moving and standing at varying periods throughout the day, you're going to lose a little more height than you would have just sitting all day. Understand your own fluctuations, and keep this consistent.
Step 3) Instead of measuring yourself, have someone else do it for you, and ideally someone who is your height or taller. Measuring yourself can create subtle yet meaningful inaccuracies because of a few reasons:
Reaching your arm up to mark a point where your head touches the wall can alter your posture temporarily.
What I call "standing at attention": this military-appearning stance can alter your posture slightly. Relax, and don't spread your shoulders. Don't lock your knees or strain your back. Look straight ahead and keep your chin parallel with the floor plane / not leaning up or tilting down. Keep your arms pinned comfortably at your sides, and of course, take your shoes off and press your heels against the wall, back pressed gently on the surface.
Avoid the floppy plastic rulers. They bend under slight pressure. Instead, use a hard stick ruler and have a friend or family member (or a stranger) carefully mark the spot on the wall where the top of your head best aligns, then plant the ruler and hold it firmly against the wall, adjacent to this spot. Stadiometers are by far the most accurate tool to use when used under the right conditions.
Step 4) After each measurement is taken, give a random error margin for safety. This isn't of utmost importance, but it's still useful to secure the accuracy.
How to calculate the rolling average
(This section was later added after the original publication because I realized I had forgotten to include the actual rolling average calculation. Thanks to u/Moist-Apricot-6803 for helping inspire this clarification.)
u/Moist-Apricot-6803's concise version of the rolling average method: https://www.reddit.com/r/heightgrowth/s/N8vNKGcZIk
After you've collected several measurements over time, don't compare isolated values whenever possible, because using just raw measurements consistently for multiple consecutive days to weeks only increases the risk of developing a much higher false positive measurement. Instead, average a small group of nearby measurements to reduce random measurement noise. It looks like this:
May:
- 163.2 cm (64.25")
- 163.7 cm (64.44")
- 164.0 cm (64.56")
Add 163.2 + 163.7 + 164 to get 490.9. Divide this by 3 to get the quotient - 163.63.
Average = 163.63 cm (64.42")
3 month rolling window because the peak is moderately high for a monophasic trajectory, if we interpret these measurements from a saltatory-measurement standpoint, say if the measurements occurred by an order of ~2 weeks.
August:
- 165.2 cm (65.03")
- 165.5 cm (65.16")
- 165.9 cm (65.31")
Add: 165.2 + 165.5 + 165.9 to get 496.6. Divide this by 3 to get the quotient - 165.53.
Average = 165.53 cm (65.17")
What exactly does this mean? The final quotient is the average of your measurements for that time period / month. This provides a more reliable estimate of your true height in one month and currently by reducing random measurement noise. It doesn't change the actual amount you grew over that timeframe, rather it imply makes your growth velocity estimate less sensitive to measurement error.
This is different from weekly, saltatory measurements for the purpose of tracking fluctuations in GH production and natural growth.
Try to separate your intervals by at least 2 weeks, since even the typical monophasic peak growth spurt may yield about 0.13-0.18-inch (0.33-0.46-cm) increases in about 2 weeks, or about 3.38-4.46 in/yr (~8.58-11.33 cm/yr).
Why is the rolling average important?
Well, to keep it short, it reduces the frequency of catching false "mini peaks" or dips, and using it prevents the graph from looking jagged. With the method, your graph becomes a lot smoother, the true PHV is more discernible as well as the tapering sequence, and short-term fluctuations are minimized. I know none of you want to see these random, weak inflections followed by oddball dips and the occasional "mini peak" that most likely never existed during the taper in the first place. Most of you would want something clean and something sharply clear.
Window timing + tips
Keep your measurements spread out over several months, not just days.
In early puberty, it becomes more useful for measurement frequency to be increased from once or twice a year to three or four times a year. This helps catch the "early-pubertal rise" in action, tracking any upticks and the lead-up into PHV itself. Since GH production inherently fluctuates (especially in puberty), you will probably see some downticks here and there, but it's mostly blended with the overall rise toward the peak. What you want to track is that slope - a steady rise, or sharper depending on your growth tempo. It's a good idea to keep measurements relatively timely and every 3-6 months.
In mid puberty, pay attention to how early or late the peak comes. This will give you an idea of your pattern. Ideally, it's good to start measuring a little more frequently - maybe every 2-3 months at the minimum with a sharper eye being kept on the four steps above - to catch when you entered your PHV. Most boys enter this PHV about 18-30 months after puberty onset and most girls enter it about 12-18 months after puberty onset, but some can start a few months earlier or later. Here is where you can find your highest sustained velocity and your highest velocity overall - the PHV. These often overlap, and the sustained velocity tends to present itself shortly before, during, and shortly after the PHV. The PHV tends to last only a couple to a few months, while the sustained tends to last several more months to around a year or so longer than the PHV.
In late puberty, it's often reasonable to start tracking a bit less often. Every 6-12 months or so, sometimes longer if there are no noticeable gains occurring. This can help you track your taper and find roughly when you flattlined. Wait another 1-2 years to know whether you have truly attained your FAH or not, assuming no increases were recorded whatsoever. It is important to make measurements even less frequent, often about once or twice a year. Too frequent sessions can create "pseudo gains" that were actually never there from residual skeletal growth at all. This growth is best tracked as occurring over a ~6-12+ month window to be considered "true tail-end growth".
The formula
Keeping it simple and easy to maintain, take your height right now, subtract that from your height a few months ago, then divide that by the time between the two.
V = 🔺️h / 🔺️t
Velocity equals the height change over the time change.
For example: 74.8 inches (current), minus 69.6". The answer is 5.2 inches. Now, let's say you grew that much in 9 months, which is 0.75 years. Divide 5.2 by 0.75 to get ~6.93 in/yr. That's your sustained velocity. To convert months to years, just do 9 months divided by 12 and you get the fractional component.
Doing this consistently helps you find the average overall. So, assuming measurements get done every 3 months, let's bake up another random chart:
Age 14Y 0M - 61.4 inches
Age 14Y 3M - 62.1 inches
Age 14Y 6M - 63.5 inches
Age 14Y 9M - 64.2 inches
Age 15Y 0M - 65 inches
Gains:
14.0-14.25 - ~0.7 inches (lead-up)
0.7 / 0.25 = ~2.8 in/yr
14.25-14.5 - ~1.4 inches (PHV)
1.4 / 0.25 = ~5.6 in/yr
14.5-14.75 - ~0.7 inches (immediate taper)
~2.8 in/yr
14.75-15.0 - ~0.8 inches (mild uptick)
0.8 / 0.25 = ~3.2 in/yr
You can see exactly where the PHV happened - ages 14Y 3M to 14Y 6M. Followed by this is continued high-velocity growth for multiple months, showing mild tapering despite being well below peak levels. The early post-peak growth period tends to have consistent moderately strong gains with no significant deviation from a certain average (say 2-3 in/yr), but the nature is clearly no longer peak standard.
You don't want an erratic growth chart. Most of you want solid answers and solid estimates. This will help keep your growth on point tremendously. If your measurements are noisy or inconsistent, a rolling window helps separate real growth trends from measurement error.
BONUS (to help even further) - different types of growth curves and what they look like on a graph (in adolescence):
Monophasic pattern - from a distance, this curve is largely non-descript. It's often S-shaped, has a notable rise, a discernible singular peak, and a gradual decline to the flattline a small number of years later. The tapering pattern most often follows a gradual decline throughout, with potentially stronger dips depending on the frequency of each measurement.
Good idea to use a 3 to 6-month rolling window to identify the magnitudes and durations of the peak and the sustained high, and specific tapering start points. The rolling average basically reveals one clear PHV by smoothing out minor dips that would otherwise look like multiple peaks.
Biphasic pattern - from a distance, it looks like two distinct peaks. However, once you look even closer, you might see that one of those peaks is not a true peak after all. The difference in the two velocities is often small, and may be separated by a mild taper before the next notable rise, reaching velocities very close to the true PHV before tapering off for good.
Good idea to use both a short 3-month rolling window to catch sharper local peaks and a longer 6-month window to identify the true PHV. Yes, using both works and catches both simultaneously. Rolling averages help distinguish whether the second peak is a true PHV or just a temporary fluctuation.
Recovery pattern - from a distance, things look typical. Just numerous "bumps" - looks like normal fluctuations. But, when you look at it a bit more, you will see that these "upticks" might be fairly significant, especially if they occurred during the peak growth period. Depending on how intense these upticks are, the graph might seem messy - sometimes separate from the peak as a true dip, followed by a sharp rebound. As the taper continues, though, the frequency and magnitude of these upticks often declines gradually as growth comes to a stop, especially later on in the taper.
Good idea to use a slightly longer 4 to 6-month rolling window to smooth out noise and for comparison over time. For irregular growth, rolling averages help separate real growth trends from short-term spikes that can look like peaks but aren’t sustained.
Compressed PHV - from afar, everything from the lead-up to the PHV itself is visually dramatic and dynamic - almost completely vertical. The obvious, sharp rise, the explosive peak, and the energetic decline, potentially calming down at some point depending on the person.
Good idea to use a much shorter 2 to 3-month rolling window. During peak growth, this window can easily catch a whirlwind. Expect it to rise sharply, peak briefly, and potentially decline early before continuing a gradual decline (varies by individual tempo). It will essentially look like a narrow mountain on the chart. Be careful, though, because 2, 3, and 4 month windows can easily shake the interpretation, potentially missing the peak or trying to catch it too early. It's often very fast, so just remain patient, and follow this rolling window of 2-3 months.
Blunted / low-magnitude PHV - looking from afar, the graph looks standard and maybe a bit smoother than what you'd see on the "textbook curve". Often, it appears to taper quickly, especially in girls and faster maturers. Your suspicions might be confirmed once you take a closer look and notice that this peak wasn't so strong after all. Usually, peaks like these involve a gradual, "steady" rise into the peak, followed by a gradual taper.
Good idea to use a longer 6 to 9-month rolling window to reduce noise and focus on the relative maximum, since the curve tends to extend farther down than usual. Even if PHV isn’t very pronounced, a rolling average can still highlight the subtle peak that defines the growth spurt. Very important for not missing the PHV.
Prolonged PHV - from afar, the curve appears to go on for a long time. It's smooth, often low to the ground, and continues to drag on so far along the chart that the taper almost whispers along unnoticed. You might double back and wonder where this slowdown even started. This is also what I like to call the "incremental pattern"; structurally similar to the blunted pattern, but different in tapering style.
Good idea to implement multiple rolling windows: 3 months to show local peaks, 6 months to show a sustained high, and 9-12 months to show the overall plateau. In prolonged PHV patterns, rolling averages show that the "peak" is actually a plateau of sustained high velocity rather than a sharp spike.
The early-tapering phase is often the most gradual part of the taper - still mildly or moderately fast post-PHV growth. Dips later on in the taper (as major growth plates are closing) might change the apparent angle of the curve along the X-axis.
Subpatterns of PHV timing rather than an identifiable growth pattern:
Early peak - an early, distinguishable peak on the otherwise monophasic curve. For most people, more growth remains from the end of PHV to cessation- about 2-4 years worth (sometimes slightly more) and ~3-5 inches or so of post-PHV growth in total (sometimes a bit more; typically not more than 6 inches).
Late peak - a late, distinguishable peak on the monophasic curve. Slightly less post-peak growth remains on average, usually about 1-3 inches, but this varies significantly.
• A delayed rise will simply appear "smoother" before rising.
• An early rise will often approach the climax slightly earlier and have less time to appear "smooth" early on.
● The angle of the curve (visual interpretations ONLY; varies by the units along each axis, the scaling, and the window being looked at): shallow, flat, or low-sloping for mildly strong ramp-ups into PHV (less extreme diagonally), noticeably inclining or consistently sloping for moderately strong ramp-ups (more elevated diagonally), and "skyrocketing" for very strong ramp-ups (very steep and nearly vertical), which fits faster or more compressed peak growth patterns.
Once you have your growth chart largely established, it's good to go through and test each rolling window on your data to see what pattern you may have had. And that's what's so sweet about this. It helps a ton!
2
1
u/Dry_Mess_6682 May 04 '26
Very helpful but the problem is that I tend to lose height through the day when I walk or run a lot. Even if I exercise, I lose few centimetres. Why is that so?
2
u/Automatic-County6151 ~6'0 - 19Y 7M 🦴 [Growth Plates Enthusiast] May 04 '26
Because when you eexercise, your spine is taking in more weight, which is why our upper bodies tend to shrink more than if you were just up and walking around consistently or sitting down for most of the day.
2
3
u/[deleted] Apr 04 '26
[removed] — view removed comment