Why self-measurement is hard
For a circumference you must locate the landmark, hold the tape level, keep it snug without pulling, and read the number, all simultaneously. Any one of those going wrong shows up in the result.
The string method solves it
- Cut a piece of string. Non-stretchy is essential.
- Wrap it around the measurement.
- Pinch or mark where the ends meet.
- Lay it flat against a ruler.
You have separated measuring from reading. That single change removes the biggest source of self-measurement error, because you can now take your time.
An elastic cord will stretch and give you a smaller number than reality. This is the most common mistake with this method.
The easy measurements
Inseam, arm length, shoulder width and torso length are all straightforward alone, because both endpoints sit on your body. Measure inseam from the crotch to where trousers sit on your shoe, with the shoes you normally wear.
The hard measurements
Chest, waist and hip. Waist is the worst because the natural waist is the narrowest point of a curve, which is a judgement call rather than a landmark.
Published inter-observer error for waist runs from 1.4 to 15 cm, so this is where care pays.
Conditions
- Morning, before eating, when girth is smallest.
- Close-fitting clothing, or measure over underwear.
- Stand naturally, weight even, arms relaxed.
- Breathe normally. Do not suck in.
- Keep the tape level, using a mirror to check.
- Three readings each, using the middle value.
Landmark tips
- Chest — fullest part, tape level all the way round.
- Natural waist — narrowest part, usually just above the navel.
- Hip — widest point of the seat, about 20 cm below the natural waist.
- Neck — narrowest point, just below the Adam's apple.
- Shoulder — point to point across the back.
What you still cannot do alone
Measuring across your back while reading at the front is genuinely difficult, and assessing how fabric sits across your shoulders is not a measurement task at all.
For alterations, a second pair of hands still helps.
Is it worth it?
Yes. Recorded once, seven core measurements remove the need to guess your size indefinitely.
More in methods for measuring alone and the professional standard.