It comes as a surprise to many travellers when they first weigh their cabin bag empty -- the average heavy-duty nylon business wheel-aboard weighs about 5KG!
That leaves a piffling 2KG for the contents of the bag, given Qantas and Virgin Australia's weight limit of 7KG.
It then becomes obvious why, on the occasions that an efficious flight attendant has insisted on weighing the cabin bag, it has always been overweight.
You can flip that equation around by investing in an ultra-light cabin bag.
One popular one that claims to be the world's lightest wheel-aboard hard-case is the XCase by Toronto-based luggage maker Heys.
It's made of ABS/polycarbonate composite which is deformable (it springs back into shape if dented) and has a frameless design, which keeps weight low.
The handle is aluminium, rather than steel, and it has two partially recessed wheels with high quality metal bearings.
If something does go wrong, though, it has a five year worldwide warranty.
The weight for the 20" model? A mere 2.3 kg.
Australian Business Traveller has seen slightly lighter bags, but they tend to be made of light fabric stretched over a frame, which makes us nervous thinking about laptops and other gadgets typically packed in carry-on.
You can order the Heys Xcase from Amazon.com for US$69.99 ($65.18), though they don't ship directly to Australia. You'll need to use a US shopping service like PriceUSA. Postage would cost approximately another US$70.
Even lighter again...
Since writing this article, one of our readers has pointed out that the Samsonite Cosmolite 55cm case is even a tad lighter, at 2.22kg.
You can read more about this case at Samsonite Australia's website.
It's made of the miraculous Cosmolite material, patented by Samsonite, that has woven/layered polypropylene for unbelievable strength. Most shops that sell Cosmolite cases have a sample of the 'fabric' available that you can bend and fold as hard as you want, and then marvel at how it springs back into shape no worse for wear.
The Cosmolite spinner has a commensurately top-of-the-line price-tag, unfortunately, at $499.