Z-CoiL Footwear generally runs true to size.  If you are familiar with EURO or CM size please see the conversion below.  If you would like to check your size in inches — step on a ruler or measuring tape and use the guide below.

Size Conversion


Z-CoiL footwear is very ergonomically designed.  Built with a rounded heel and raised arch we strive to support each contour on your feet.  If you have a flat foot (flat arch), an adjustment will likely need to be made to lower the built-in arch.  The toe box of Z-CoiL is wider than normal shoes and designed to prevent irritation in the toes and ball of the foot.  In general, the ball of the foot is wide — however the width will vary slightly by style.  Its important that you wear shoes that prevent cramping or squeezing of the toes.  Tension on the toes can easily lead to bunions and disfigurement of the toes and ball of the feet.  Its important to set your toes free and allow them to spread out naturally with each step.

1/2 Sizes

Z-CoiL does not make half sizes.  Instead all Z-CoiL Footwear ship with an extra 3 mm insert that makes up 1/2 size. Add the insert as follows:

1.  Remove the Z-CoiL InsoleOne Half Size Insert from Z-CoiL

2.  Insert the 1/2 Size Insert

3.  Replace the Insole

The video explains how to make the simple adjustment.

3mm insertClick Here:

Spring Strength:


Z-CoiL has 4 different sized springs.  The size of the shoe dictates what size of spring is loaded at the factory.  In some cases, customers will choose a softer or stiffer spring based on their weight or gait type.  Your objective should be to compress the spring about 75% during a normal walk (or a normal run — if you run in Z-CoiL’s).  If you “bottom out” on the spring, you may want to consider a stronger spring.  If you feel your shoe is too stiff, you may consider a softer coil.   The vast majority of consumers do not change the factory spring strength.

  • Women’s sizes 5~7 are factory loaded with a small spring.
  • Women’s sizes 8~11 & M8~9 are factory loaded with a medium spring.
  • Men’s 10~13 are factory loaded with a large spring.
  • Men’s 14+ are loaded with an XL spring.
Coil Size Typical weight Weight range of
successfully fitted customers
6.2 mm Small up to 150 lbs. 90 to 300 lbs.
6.5 mm Medium 120 – 200 lbs. 90 to 350 lbs.
7.2 mm Large  160 – 240 lbs. 90 to 350 lbs.+
7.5 mm X-Large 220 lbs. + 90 to 350 lbs. +