How to measure your height accurately at home

What you need

For the most accurate measurement at home you need very little:

• a flat wall or door frame with no skirting board where you stand, and a hard floor (not carpet);
• a ruler, or anything stiff with a straight edge, to rest on your head;
• a pencil or a sticky note to mark the wall;
• a tape measure, ideally a metal one that stays straight;
• a helper, if you can find one. It's easier, but not essential.

Don't have a tape measure? Skip to measuring with your phone: it needs nothing but the phone in your pocket.

Preparation

• Take off your shoes and socks. Most shoes add 2-3 cm.
• Remove heavy outer clothing so you can stand flat against the wall.
• Flatten your hair. Take out buns, ponytails, clips and headbands. Thick or curly hair should be pressed down when you measure.
• Choose a hard floor. Carpet and rugs compress under your heels and make you look shorter.
• Measure in the morning if you can. It's when you're at your tallest (more on that below).

Standing correctly

Most height mistakes come from posture, not from the tape. Stand like this:

• Heels together, touching the wall, with your weight evenly on both feet.
• Bottom and shoulder blades touching the wall. The back of your head may touch too, but don't force it.
• Legs straight, knees not locked back, arms relaxed by your sides, shoulders level.
• Look straight ahead. Your chin should be level, so an imaginary line from your ear hole to the bottom of your eye socket is parallel to the floor. Clinics call this the Frankfort plane. Tipping your chin up or down changes the reading.
• Take a breath in and stand tall, without lifting your heels.

Marking and measuring

1. Take off your shoes. Remove shoes, thick socks and heavy clothing, and take out hair clips, buns or anything on top of your head.
2. Stand against a flat wall. Stand on a hard floor with your heels together and touching the wall. Your bottom and shoulder blades should touch it too.
3. Stand tall and look ahead. Legs straight, arms by your sides, shoulders level. Look straight ahead so your chin is level, not tipped up or down.
4. Rest a ruler on your head. Someone places a ruler flat on the top of your head, level and at a right angle to the wall, pressing down just enough to flatten your hair.
5. Mark the wall. Mark the wall where the underside of the ruler touches it, with a pencil or the edge of a sticky note, then step away.
6. Measure floor to mark. Measure from the floor straight up to the mark with a tape measure. Read it to the nearest millimetre or eighth of an inch.
7. Repeat and average. Measure two or three times and use the average. If two readings differ by more than half a centimetre, measure again.

That number is your real height. For comparison, two trained nurses measuring the same person with a clinic stadiometer usually agree within 3-5 mm, so a careful home measurement within about 1 cm is doing well.

Measuring your height by yourself

No helper? You can still check your height by yourself. Stand against the wall as above, rest a ruler flat on your head, and keep it pressed to the wall with one hand. With the other hand, slide a sticky note up the wall until it touches the underside of the ruler, and leave it there. Step away and measure from the floor to the bottom edge of the note. A mirror in front of you helps you keep the ruler level.

You can also measure that sticky note with your phone camera instead of a tape: aim at the floor directly below the note, then at the note itself.

How to measure your height with your phone

If there's no tape measure in the house, CheckMyHeight measures your height with your phone camera, free and in your browser. There's no app to download and nothing to print or hold. It uses the same augmented-reality technology as Apple's Measure app and Google's ARCore: as you move the phone, it maps the room in real metres, then measures from the floor to the top of the head.

1. Stand barefoot on a hard floor, 2-3 metres from the person holding the phone.
2. Open checkmyheight.com on the phone and tap Measure my height. Allow camera access (and motion access on iPhone).
3. Move the phone slowly from side to side for a few seconds so it can find the floor.
4. Aim the dot at the floor between the feet and tap +, then aim at the very top of the head and tap + again.

Your height appears live in feet and inches and in centimetres, with your percentile and the celebrities who are exactly your height. The camera feed stays on your phone and is never uploaded.

Why you are taller in the morning

Between the bones of your spine are discs that act like cushions. While you sleep, lying flat, they soak up fluid and expand. During the day, standing and sitting squeeze some of that fluid out, so most people are about a centimetre shorter by bedtime. That's why clinics prefer morning measurements, and why you should always measure at the same time of day if you're tracking your height or a child's growth.

Measuring a child's height

Children aged about two and up are measured exactly like adults: shoes off, heels to the wall, looking straight ahead. Make it a game so they stand still, and ask them to "stand tall like a soldier" for a moment. Babies and toddlers under two are measured lying down, which a doctor or health visitor does with a measuring board.

Measure children every six months or so, at the same time of day, and write the date next to each result. If you'd like to know how tall they're likely to be as adults, try the height calculator or the mid-parental height calculator.

Common mistakes

• Keeping shoes or thick socks on.
• Standing on carpet or a rug.
• Tilting the ruler, so it touches the wall higher or lower than your head.
• Looking up at the ruler instead of straight ahead.
• Letting the tape measure sag or run at an angle instead of straight up.
• Measuring once, at night, and trusting that single number.

What to do with your height

Once you know your real height, see how you compare with the average height for men and women, convert it with the feet to cm converter, check your BMI, or put yourself next to your favourite stars on the height comparison chart.

Questions