Twenty minutes with a tape measure removes most of the uncertainty from buying clothes online. Do it once, write the numbers down, and keep them in your phone.

Before you start

  • Use a soft tape measure, not a builder's tape
  • Wear close-fitting underwear and the bra you usually wear, since it changes the bust measurement significantly
  • Stand normally, not straight-backed and braced
  • Keep the tape snug but not tight — it should sit against you without compressing
  • Get someone to help with the back measurements if you can

Breathe normally. Holding your stomach in produces a number that is no use for buying clothes.

The six measurements

1. Bust or chest. Around the fullest part, tape level all the way round and flat across the back. For a bust measurement, keep the tape parallel to the floor rather than riding up at the back.

2. Natural waist. The narrowest part of the torso, usually an inch or so above the navel. To find it, bend sideways — the crease that forms is your natural waist. This is not where trousers necessarily sit.

3. Hips. Around the fullest part, usually seven to nine inches below the natural waist. Include the fullest part of the seat.

4. Inside leg. From the crotch to where you want the hem, in the shoes you would wear with it. Measure a pair of trousers that are the right length rather than measuring yourself, which is awkward and unreliable.

5. Shoulder to shoulder. Across the back, from the bony point of one shoulder to the other. The most useful and least-taken measurement, because the shoulder is what decides whether a structured garment works and it is the hardest thing to alter.

6. Arm length. From the shoulder point, over a slightly bent elbow, to the wrist bone.

The more useful set

Body measurements tell you about you. Garment measurements tell you about what you are buying, and they are what most product pages give.

So take a second set, from the garment you own that fits best in each category:

  • Flat chest — laid flat, armpit to armpit, doubled
  • Length — shoulder seam to hem
  • Sleeve — shoulder seam to cuff
  • Flat waist for trousers, and the inside leg

Comparing garment to garment is far more reliable than comparing your body to a size chart, because it accounts for the ease built into the cut.

Keep them somewhere useful

A note in your phone with both sets. That is the whole system.

Re-measure once a year, or after any significant change. Bodies change and old numbers cause the same problem as no numbers.

Using them

Most product pages give either a size chart or garment measurements. If they give garment measurements, compare directly to your second set. If they only give a size chart, compare to your body set and expect the fit to include some ease.

If they give neither, treat that as a signal about the retailer and order accordingly.

Why clothing sizes are inconsistent explains why the label itself is not worth trusting, and fit words translated covers what the descriptions mean.