I bought size 39 online, ended up exchanging them for a size 38, and the 38 is perfect for my feet which are 25.0cm long. Would say the boots run long rather than wide - i have normal to narrow feet so no issue for me, but if you have wide feet these may not be the boot for you.
I also have larger calves - about 44cm circumference. These fit my calves without being too tight, whilst being slouchy at the ankle. Exactly what ive been looking for!
Bought the chocolate brown which is gorgeous with a lot of trending pieces at the moment. Probably going to come back for them in black too.