Obviously they don't put the weight on the product main page, that is absolutely heavy.

The Helinox Chair Zero is the standard by which all backpacking chairs are compared https://helinox.com/products/chair-zero - and it is 1 lb 1 oz.

And then some people mod these chairs, like this similar one that was reduced to 13 oz. https://backpackinglight.com/forums/topic/chair-enlightening...