Important - See below the table for Corset sizing....

International Sizing Chart
  Regular Sizes Plus Sizes One Size
S M L S/M M/L 1X/2X 3X/4X OS OS (Queen)
Dress Size UK 6-8 10-12 14-16 6-10 12-16 18-20 22-24 6-16 18-24
France/Spain 34-36 38-40 42-44 34-38 40-44 46-48 50-52 34-44 46-52
Germany 32-34 36-38 40-42 32-36 38-42 44-46 48-50 32-42 44-50
Italy 38-40 42-44 46-48 38-42 44-48 50-52 54-56 38-48 50-56
USA 2-6 6-10 10-14 2-8 8-14 16-18 18-20 2-14 16-20
Japan 5-7 7-9 9-11 5-9 9-13 13-15 15-17 7-13 13-17
Cup A/B B/C C/D A/B C/D D/DD DD A/C D/DD
cm Bust 81-86 86-91 91-97 81-86 91-97 90-108 108-122 81-97 90-122
Waist 61-66 66-71 71-81 61-66 71-81 81-102 102-112 61-81 97-112
Hip 86-91 91-97 97-102 86-91 97-102 106-122 127-142 86-97 107-122
Inside Leg (Inseam) 88 89 90 89 90 93 94 89 93
Rise 18-19 19-20 20-22 19-20 20-22 23-24 24-25 19-20 23-24
kg Weight 40-55 55-65 65-75 45-60 60-75 75-105 105-125 40-70 75-115
inches Bust 32-34 34-36 36-38 32-34 36-38 40-48 48-54 32-38 40-54
Waist 24-26 26-28 28-32 24-26 28-32 36-40 40-44 24-32 36-44
Hip 34-36 36-38 38-40 34-36 38-40 42-48 50-56 34-40 42-56
Inside Leg (Inseam) 34.5 35 35.5 35 35.5 36.5 37 35 36.5
Rise 7-7.5 7.5-8 8-8.5 7.5-8 8-8.5 9-9.5 9.5-10 7.5-8 9-9.5
lbs Weight 90-120 120-140 140-160 90-130 130-160 165-225 225-275 90-160 165-275

Special Note For Corset Sizing...

Sizing your Corset
You would measure for your corset like you would measure the band size for your bra.

Finding your Band Size
Standing in front of a mirror, wrap your tape measure snugly around your chest, just under or at the crease beneath your breasts and flush against your back. Check in the mirror to make sure the tape measure is parallel to the floor and flat across your back. You may need a friend or partner to help. Record this measurement in inches and write it down.

Now you’ll need to do some basic maths to find your proper band size.

If the number is even, add 4 to get your Band Size
If the number is odd, add 5 to get your Band Size

Example:
If you wrote down 32, add 4 and your band size will be 36, this will also be your corset size.
If you have a DD cup size or above you would go one size larger.