That's a great question, and neither measurements nor estimations are the best way to determine how much skin to remove. Using measurements to decide how much to remove is inherently flawed, because taking out a symmetric piece of skin is no guarantee you are leaving behind a symmetric abdomen. Also, whatever measurements you get depend on how much stretch you put on the skin when measuring. Many patients have a little more skin on one side than the other, and/or more stretchiness on one side than the other, and the surgeon needs to factor this in. It's what you leave behind that matters. Also, estimations are nice, but not precise. Generally speaking in most full tummy tuck candidates, especially if they have had kids or lost significant weight, the skin between the upper border of the belly button and the lower incision will be removed. I tailor the amount of skin I take out based on the amount of skin excess and the degree of laxity present. I start with marking the tummy tuck incision along the lower abdomen with the patient in the standing position. I prefer to plan for the incision to sit low, so it can be hidden in a bikini, and to be smooth and symmetric. (as opposed to the jagged incisions you can see if you look online at a bunch of before and afters) Planning this incision is a criticial step in how the final incision will look. I pull the skin up with the amount of tension I estimate will be on the skin after the excess is removed. Doing this allows me to put the scar in a position most likely to be hidden. Skipping this step means the incision will sit higher or possibly more irregularly than I want. The interesting thing here is most patients do have some small asymmetry in how much skin is present side to side, so this must be accounted for not only during marking of the lower incision, but also in marking the upper incision. This lower incision is made, and the flap of skin and underlying tissue is elevated all the way towards the xiphoid (lower part of your breastbone) and margins of the ribs on either side of the xiphoid, carefully going around the belly button. Then any hernia repair or rectus diastasis repair is performed. After, the bed is flexed so the patient is bent forward at the waist to allow for removal of the excess skin. The incision marking the upper border of skin removal is then drawn out, placing equal amount of tension on the skin on right and left sides when marking, to obtain the most symmetric result. The amount of skin will vary patient to patient, and not all patients have enough laxity or looseness to get that amount out, and in those cases there are variations made in technique. The term mini-tummy tuck is often confusingly used to refer to different surgeries, so this is more surgeon specific. For example, some do a full dissection and repair and only limit the length of the scar (so basically a short scar tummy tuck) whereas others do only skin tightening and repair of the lower abdomen. The way the belly button is managed is also very surgeon specific, and looking at before and afters is a good way to see how this can differ. Seeing a board certified plastic surgeon in person would allow for a history and physical to tell you how much skin would be expected to be removed for you in particular.