Correct ring sizing - wheatsheaf, ring sizers etc

Morning everyone,

What is your experience of accurately sizing a ring. Do you use a wheatsheaf ring stick, or other ring sizers and whether the different types are accurate, or not. Some people swear by Wheatsheaf, saying their sticks are accurate, whereas other cheaper versions are not.

Do you calculate the size of the ring by putting the ring up to the line on the wheatsheaf, over the middle of the line?? I have read that some calculate up to the line, others have found they always use the middle of the line to calculate an accurate ring size. Then of course there are spinner rings, comfort fit etc etc

I'd be very interested to hear your experiences and tips.

Thanks xx