I have been searching for reviews of the Sonnie sneakers before buying and this is all I found (partially contradictory):
- true to size/more on the smaller side
- very narrow
- not for feet with a high arch
- Half size: size up
- Half size: size down
- heel too high
The length of my feet is 25.2 cm. According to the measurement I am a EU40 but most of my shoes are a 39.5 or 39 (UK6).
I have normal feet, neither very narrow not wide.
My arch is pretty high. I have issues with nearly all boots which do not have a zipper (e.g. I am not able to get my feet into the Classic Mini UGGs because of the instep/arch).
I ordered the low Sonnie sneakers in white leather in size 40 and here is my experience:
The length of the insole is nearly perfect for me. Although it looks like it is slightly too short (it is only 2-3 mm longer than my foot) the sneaker itself feels very roomy.
I had NO issues regarding the width and I am not sure why most reviewers found the sneakers to be narrow. Honestly I would say they are pretty wide and I had to tighten the strap a lot just to avoid slipping around in it.
Also I have no problems with the instep although one reviewer said she wasn’t able to close the clasp because of her high arch.
I have to open the clasp to get into the shoes and I am not able to „slip in“ but after closing there is more than 3 cm of the strap left.
The heel height does not seem to be a problem for me. There is no rubbing and the fit perfectly.
Maybe my experience will help others to decide on the style or the size.
