So funny story... I live outside the US and so have no idea what an oz is. I ordered on earth day when the wonderful team at popflex active were giving away a free reusable drink bottle. I was scrolling through the main accessories page to decide which bottle to pick. Going off the photos this bottle looked like a short but fat drink bottle compared to the other drink bottle. I guessed the smaller one was 750ml and this one was 1L. I was so wrong, and definitely reccomend converting to mls before you order. It was massive when it arrived. Like truly massive. I am a mum to a newborn so it actually worked out really well for me. I drink at least 2 of these per day and one overnight to keep up with breastfeeding demands. Just be aware, these are huge. The other bottle in the photo is 750ml for reference.