• The Oxa Shirt is designed and tested for men, with a size range between 82 and 119 cm (32.35 - 47 in).
  • The Oxa Bra is designed and tested for women, with a size range between 67 and 96.5 cm (26.5 - 38 in).

To determine your size: 

You need a flexible measuring tape, string, or rope, at least 120 cm (4 ft) long.

  1. Ask someone you trust to take your measurement. Measure without a top/shirt.
  2. Measure your circumference at the bottom of the breastbone, where the rib cage joins together.
    • Measure in a straight, horizontal line. Tighten the tape so it doesn’t slide down the back/front.
    • Lower your arms and elbows at your sides.
  3. Note the nearest centimeter / half inch measurement.

To ensure the best fit for your Oxa bra or shirt:

  • Maintain a neutral posture. Relax your shoulders.
  • Breathe softly. Do not take deep breaths.


If you:

  • are alone? Use a mirror to check your posture and horizontal measurement. Measure twice to be sure.
  • use a string? Mark the measurement by hand, and measure the string after removing it from your body.

Review the measurement instructions as a PDF.

Why is it so tight?

Oxa measures your breath and heart signals directly at the surface of your skin and works best with a close-fitting connection when the electrode sensors rest snugly on the thorax (mid-torso).

What if you don't have my size?

The first generation of Oxa will be limited to the ranges listed above; for other measurements, Oxa looks forward to our growth together.