Protocols · Do it the same way every time
How to Measure Your Child's Height Accurately, at home
Small technique differences add up: at some ages the reference median moves only about 3.0 inches across an entire year (CDC Growth Charts, boys 13→14), so sloppy technique can easily produce a bigger difference than months of real change. The method below follows the measurement procedure described in the CDC's NHANES Anthropometry Procedures Manual, adapted for a wall at home.
The protocol
- Set up. A hard, uncarpeted floor against a flat wall. You'll need a metal tape measure, a pencil, and a flat rigid object — a hardcover book or clipboard.
- Prepare. Shoes off, thick socks off, hair accessories and high hairstyles down — anything on the crown adds height.
- Position. Heels together and touching the wall; buttocks and shoulder blades against the wall too, arms relaxed at the sides.
- Head level. Eyes looking straight ahead, so the line from the ear canal to the bottom of the eye socket is horizontal (the survey manual's head position). Not tilted up — chins rise instinctively.
- Headpiece. Press the flat object level against the wall and lower it to the crown, pressing gently through hair until it touches the head. Keep it at a right angle to the wall — this is where most home measurements go wrong.
- Mark and step away. Mark the wall at the bottom edge of the object, then have your athlete step out.
- Measure. Metal tape from the floor to the mark, tape held straight and vertical. Read at eye level, to the nearest 0.1 cm or ⅛ inch.
- Repeat once. Take it twice; if the two differ by more than about a quarter inch, take a third and use the middle value.
The mistakes that add half an inch
- Measuring on carpet (the tape start point sinks).
- A tilted headpiece — anything but a right angle reads tall.
- Chin up instead of eyes-forward.
- Socks, insoles, or a high hairstyle under the headpiece.
- Comparing a morning measurement to an evening one.
Protocol reference: CDC, National Health and Nutrition Examination Survey (NHANES) Anthropometry Procedures Manual.
Common questions
How often should we measure?
For most families, monthly is plenty — more often mostly measures noise. What matters is consistency: same wall, same method, a similar time of day, recorded every time.
Why does time of day matter?
Measurements taken at different times of day can differ slightly, so comparing a morning measurement to an evening one adds avoidable noise. Pick a routine and keep it.
Tape measure or phone app?
A metal tape against a flat wall, read at eye level, is hard to beat. Camera-based estimates vary with angle and distance and are difficult to repeat consistently.
Where these numbers come from
Every value on this page is computed by My Athlete from the CDC Growth Charts (2000), published by the National Center for Health Statistics and in the public domain. We use the charts' own published LMS (Lambda-Mu-Sigma) parameters and method — no estimates, no blended sources, nothing invented. The reference population is the U.S. reference population underlying the CDC Growth Charts (2000); it describes measured distributions, not targets. How we build these tables →
Source: CDC Growth Charts (2000), National Center for Health Statistics — cdc.gov/growthcharts. Data coverage: ages 2–20. Use of these data does not imply endorsement by CDC, NCHS, HHS, or the U.S. government. · Page last reviewed: August 26, 2026
One number tells you where they are today.
The part that actually matters is the same measurement, repeated over a season — the record of measured change over time. That's what My Athlete keeps, across 18 sports, alongside every assessment your athlete does.