Ah, but Sathor, that is what we are trying to explain. Even off-the-rack Kilts are measured differently by the different re-sellers.
Some assume that the measurement you give them will be for the smallest size of the Kilt. (smallest hole on the straps.) and some do it to the middle hole.

Some off-the-rack Kilts such as UK's are designed to be worn low and loose. Some higher.

If you are used to wearing a UK and send your UK measurements to Jerry at SWK the Kilt you get will not fit. Not even close.

This is a phenomenon that we in the Kilt world see every day. Guys today are so used to wearing jeans of "X" size that they have no idea what their real measurements are.
They have never had a tape measure wrapped around themselves.
Then they try wearing a garment that fits completely differently than jeans and it is natural to be confused.

So, the best advice anyone can give is to follow the instructions of the person you will get the Kilt from.