The new king of windshirts (by an unlikely candidate)

I have never really understood dollar-per-gram or gram-per-dollar metrics.

Really, you have a garment A that weighs 50 grams and costs 100 dollars

and you have garment B that weighs 100 and costs $50

So, first is $2 per 1 gram or 0.5 gram per dollar, while second is the opposite – $0.5 per 1 gram and 2 gram per dollar. Yeah… Now what?

We want to: minimize weight and minimize cost. So these ratios do not make any sense. This is not like we were calculating metric for hard disk drives for PC: dollar-per-megabyte, where we actually want to maximize megabytes and minimize the price. The dollar-per-gram metric is totally wrong.

You can talk of a metric like “saved X gram and payed Y for this”

In the example above, you can say that you can invest (100-50) dollars to save (100-50) grams, so the metric is: (A.price – B.price)/(A.weight – B.weight). This way you can illustrate how much money you paid per saved gram if you choose B over A. Then, since this metric is relative to specific garment, you can build a matrix where you calculate this metric between each pair of garments you consider to buy. I made something like this for quilts at the time of buying.

Sorry for the offtopic :)

Hi Gregory,

Yes, dollar/gram is not a useful measure. dollar * gram is more useful. Your formula (A.price – B.price)/(A.weight – B.weight) is correct, and I always use that when I am considering upgrades, but I don’t see the utility of the matrix. Either you have a quilt now, and you are replacing it, or you don’t have a quilt now, and you are adding it to your kit.

The more general case is you are replacing/adding n items to your kit, and want to minimize the cost per total weight.

For building a kit from scratch, it would be easy to write a computer program to find the best choices. (Does anyone know of source for tabulated price weight, data?)

What are people’s thoughts on adding pit zips to a windjacket?