The shoe size conversion chart that someone gave a link to-I would not rely on that as it seems way out compared to some other charts I have seen.

It's a pity you can't list in Australian sizes but if the shoe itself is in an Australian size, I would put the size in the title of the ad and in the description and photos.

Other than that, if you can put in the European equivalent, and also the measured length of the shoe, that might help people.

I find on the charts-and I have looked at heaps of them over the last few years-the European/Australian equivalent is usually constant but the US/Aust sizing is not. Some say it is the same but for US, you have to go up a size.

For example, size 8 women's shoe in Aust is usually 39 European. I find that is accurate as I am a size 8. But US 8 is a bit small and i take an 8.5 or 9 US.