Combining all the inches together can be very encouraging for some - kind of a summary of all the losses. It's an affirmation of the progress made.

Personally, I look at each body part separately, i.e. "I lost two inches from my waist, two inches from my hips, etc."

It can be an indication that you're getting smaller without poundage lost. Sometimes you can get smaller without losing scale weight.

You lose inches and you can fit into smaller clothes. You can even gain scale weight and that can happen.

The scale weight isn't the only indicator of health.

The bust-waist-hip measurement is generally used because it's a typical standard of measurement especially in clothing.

I don't add anything together. As a strength training male in the 14-15% bf range, losing inches from the waist is good; anywhere else is bad, or maybe means nothing, as I could have done a measurement at a time when a muscle group was particularly swollen.

I do the standard chest, waist, hip measurements...I add in a low belly measurement because that's where I tend to carry my fat...arms and legs are not a concern for me, but for some people who carry weight in those regions, they might be good indicators of fat loss...not everyone carries weight in the same place or loses weight in the same place, so for someone who carries extra weight in their thighs, tracking chest/waist/hip might not yield many changes for fat loss, while tracking thigh measurements at 3 different places on their thigh can give them a better indicator of progress...like any other metric, it's just a way to track changes over time, the individual measurement is only meaningful if it's meaningful to your specific situation...

I can't measure myself properly to save my life. According to my calculations I've gained inches. I gave up last month. My clothes are getting looser.

Most often I see folks measuring a baseline for each body part, then tracking changes to that baseline. I only see "total inches lost" in shilly adverts or the occasional person who wants to celebrate a total victory--but those folks then tend to share how many inches they lost per measurement area.

I plan to track inches per measurement area, not a nebulous "total inches lost."

I lost 40 pounds years ago using WW. I picked 7 body parts to measure for a baseline. I measured periodically at those same points. I kept a log of each individual measurement, as well as a total. I found it very encouraging to see the total number for my own motivation. When I would have few weeks of a stall on the scale, I could see changes happening with the tape measure. It was also helpful to have a total when I got closer to goal. 1/8 to 1/4 of an inch on one body part may seem small, but 1/4 inch x 7 parts added up to help me see the changes in a concrete number. It was, for me, a way to keep from getting discouraged. It also helped me not depend on the scale so much for evidence that I was progressing.

The chick at BodyFit bt Amy has a good video on how to consistently measure yourself.
https://www.youtube.com/watch?v=DZVcaYJvnSU

I love her exercise videos to death, I'm not gonna lie.

thanks baconslave that video was very helpf