Measure Height How to measure height accurately at home
Most people get a different number every time they try, and it is almost never the tape's fault. Your height genuinely changes by a centimetre or two over a normal day, and four small things about how you stand account for the rest.
What you need
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A hard floor
Carpet swallows up to a centimetre. Stand on tile, wood or a flat board.
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A clear wall
No skirting board under your heels, no radiator, no picture rail at head height.
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Something flat and rigid
A hardback book, a clipboard, a shoebox. Not a ruler you hold at an angle.
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A metal tape measure
Cloth tapes stretch. A folding rule or a steel tape both work.
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A pencil
You are marking the wall, not guessing where the book was.
No wall available? Skip to measuring without one.
The method, step by step
This is the wall and book method, which is what a clinic does with a stadiometer minus the equipment. Getting someone else to do steps 6 and 7 is worth more than any of the gear.
- 1
Take off shoes and socks
Socks are worth a couple of millimetres and thick ones more than that. Let your hair down and flatten anything piled on top.
- 2
Put four points against the wall
Heels, bottom, shoulder blades and the back of your head. If one of them is not touching, you are not standing straight and the number will be short.
- 3
Feet together, weight even
Heels touching each other, toes slightly apart, arms hanging at your sides. Do not push up onto the balls of your feet.
- 4
Look straight ahead
The line from the bottom of your eye socket to the top of your ear canal should be level with the floor. This is the standard clinical position, and tipping your chin up is the fastest way to invent two centimetres.
- 5
Breathe in and hold it
Clinics take the reading at the top of a deep breath, because the ribcage lifts the shoulders slightly and it is the one posture everybody can repeat.
- 6
Bring the book down flat
Lower it until it rests on your head and press until it stops sinking into your hair. Keep it at a right angle to the wall. A tilted book is the second most common error after the chin.
- 7
Mark the wall, then measure
Mark along the bottom edge of the book, step away, and run the tape from the floor to the mark with the tape flat against the wall.
- 8
Do it three times
Take the average. If your three readings spread more than half a centimetre, something in the setup is moving and repeating it will not fix that.
The five things that change the number
Added together these are worth more than five centimetres, which is why two honest people can measure the same person half an hour apart and disagree.
| What | Worth | Why, and what to do about it |
|---|---|---|
| Time of day | 1 to 2 cm | Your spinal discs compress through the day. You are tallest within an hour of getting up and shortest at night. Pick a time and always use it. |
| Carpet | up to 1 cm | The heel sinks and the tape end sinks with it. Move to a hard floor or stand on a board. |
| Hair | 0.5 to 3 cm | Thick or curly hair reads as height unless you press the book down until it stops moving. |
| Chin angle | up to 2 cm | Looking up lengthens the back of the neck against the wall. Looking down does the opposite. |
| Slouching | 1 to 3 cm | The biggest single variable, and the reason a friend measuring you beats measuring yourself. |
Measuring someone else
Easier and more accurate, because the person being measured can concentrate on standing still instead of reaching over their own head.
- ✓Stand to the side, not in front. You need to see the book edge against the wall.
- ✓Your eye should be level with the book when you mark. Marking from below adds height.
- ✓If they are taller than you, stand on a step rather than reaching up and guessing.
Measuring a child
Under two years old the standard is length, lying down, not standing height. Lay the child flat, one person holding the head against a fixed surface and another straightening the legs, and measure to the heels.
From two years old, use the wall method above. For growth tracking, consistency beats precision: same wall, same time of day, same person marking. A chart made of readings taken at random times says more about the times than about the child.
When there is no wall
A doorframe works, since the sides are straight and vertical. Otherwise you are into estimates, and it is worth being clear about how good they are.
Apple's Measure app
Can put a line on a person's head and give you a height, but it needs the LiDAR sensor, so it only works on Pro iPhones and iPad Pros. On any other iPhone the feature is not there.
A photo and a known object
Photograph the person next to something whose size you know, a door, a kitchen counter, a standard brick course, then scale from it. This works, and it is what our app automates.
This app
Take one photo and it reads the scale from what is already in frame, then returns height, width and depth with a confidence score and a note saying what it used as a reference.
Be honest with yourself about which one you need. A photo estimate is fine for deciding whether a wardrobe fits through a doorway. If the number is going on a passport form or a medical record, spend the two minutes with a wall and a tape.
Centimetres to feet and inches
Rounded to the nearest inch, which is as precise as anyone quoting a height in feet is actually being.
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155 cm
5 ft 1 in
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160 cm
5 ft 3 in
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165 cm
5 ft 5 in
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170 cm
5 ft 7 in
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175 cm
5 ft 9 in
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180 cm
5 ft 11 in
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185 cm
6 ft 1 in
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190 cm
6 ft 3 in
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195 cm
6 ft 5 in
Any other height? The height converter takes cm, metres or feet and inches in one box.
Questions
Why am I taller in the morning?
The discs between your vertebrae hold water overnight while you are lying down, and lose some of it once you are upright and loaded. The difference is usually one to two centimetres across a full day. Nothing is wrong with you, and there is no version of your height that is the real one. There is only the height you measured, at the time you measured it.
Should I measure with shoes on?
No, unless the form you are filling in asks for shoe height, which almost none do. Passports, medical records, driving licences and sports registrations all want barefoot height. If you want to know your height in a specific pair of shoes, measure barefoot first and measure the shoe separately.
How accurate does this need to be?
For a form, half a centimetre is far more than enough. For tracking a child's growth, use the same wall, the same time of day and the same person doing the measuring, because a consistent method matters more than an accurate one. For anything medical, a stadiometer at a clinic is a different instrument and you should use it.
Can I measure my height with my phone?
Partly. Apple's Measure app can estimate a person's height, but it needs the LiDAR sensor, so it only works on Pro iPhones and iPad Pros. Our app works from a normal photo on any iPhone by reading scale off objects already in the frame. Both are estimates. Neither replaces a wall and a tape if the number is going on a form.
What is the single most common mistake?
Holding the measuring object at an angle. People instinctively tilt a book or a ruler down towards the wall so they can see the edge, and every degree of tilt adds height. Keep it flat on your head and square to the wall, and mark the wall rather than trying to read the tape at the same time.
For everything that is not a person
Trees, furniture, doorways, dogs. One photo, three measurements, and a confidence score telling you how much to trust them.
