Measuring loft of down

I don't know if there is an industry stadard, but I personally like to know actual loft, not average. A bag, for instance, should ideally have more loft on top than the bottom, and more loft in the foot box than elsewhere. "Average" loft doesn't give you a good indication. Also, some bags have a variable loft so you can adjust down between top and bottom to change those 'averages'. Likewise, a good jacket would probably have higher loft in the torso compared to the arms. Cheaper (AKA mass produced) down goods rarely have this differential. For instance, the mass produced Mont Bell UL down inner has the same loft all over compared to, say, the custom made Nunatak Skaha.

Hi David

There are international standards. See http://idfl.com/ for one version of how it is done.

But do note that IDFL introduced their own new way of conditioning down for measurement SOLELY to get a higher 'loft rating', and this move has engendered considerable international scorn, ridicule and rejection in the trade.

Cheers

Generally a bag has its highest loft at the chest area and its lowest loft at the knees. One way to quantify loft is to get a spirit level and ruler and measure both these heights … and divide by 2.

Good working way of establishing likely warmth.

Or make your own sleeping bag and put how ever much Down you want where ever you want it.

Do the math and then make your baffles as big or small as they need to be to hold the amount of Down, by weight, that is necessary to give you what you need / want plus a bit.