Howways Home ›› Local Listings ›› SA ›› Australia ›› Howways SA Marketing and Advertising Australia, SA 5108 5108https://howways.com Hair extensions are measured by the ounce. If you plan on installing hair extensions for a full head weave, then you will need two bundles, which are 6-8 ounces in total, with each bundle weighing somewhere between 3-4 ounces.