Take your actual body measurements as they are more accurate than measuring over your clothes or shoes.
Feet: Use a ruler or tape measure to measure your foot (from the heel to the tip of your longest toe) Be sure to measure both feet. Many people have feet of different sizes. Fit to the larger of the two.
Remember, feet can expand over a quarter size during a full day's walk so ensure you get the right fit.
I recently bought a pair of these and was delighted to find a Gore-Tex lined shoe in the sale for only £50.00. My normal size didn't fit, so I had to buy a size and a half larger than I usually would, but that fitted fine. My first wearing was at Saturday's Parkrun. the trainer performed admirably, provided plenty of grip on the mixed surfaces and didn't rub or pinch as I would have expected a new shoe to do. I may go back and buy another pair.