Given the debate on the Simply yours' post on bra fitting. I decided to take hands and use the information added here at Bratabase :D.

Stats:

  • This is based on last week's backup, since then some more bras have been added.
  • The measurements are taken by the users with no supervision and by good will, although there is some validation by the site to make sure the numbers are not out of range.
  • There is no standard way of measuring a stretched band. Each user stretched the bra as much as she feels comfortable and enters that measurement.
  • Only the bras with measurements have been taken in consideration.

Band length at rest
Band size Average (cm) Average (in) Std Dev (cm) Std Dev (in) # of bras
28 58.21 22.92 3.22 1.27 123
30 61.65 24.27 3.50 1.38 300
32 65.03 25.60 4.32 1.70 195
34 69.50 27.36 5.19 2.04 115
36 74.87 29.48 4.48 1.76 50
38 79.16 31.17 5.03 1.98 28

This table contains the stretched bands, only bras with such measurement were considered.

Band length stretched
Band size Average (cm) Average (in) Std Dev (cm) Std Dev (in) # of bras
28 73.22 28.83 4.22 1.66 63
30 76.42 30.09 4.87 1.92 156
32 79.94 31.47 6.53 2.57 78
34 91.57 36.05 13.28 5.23 41
36 95.27 37.51 5.44 2.14 27
38 95.15 37.46 6.96 2.74 9

Further math shows that on average a bra's band at rest represents the 80% of its band number and that bras can stretch an average of 25%, which is enough to match the bra's band size.