20% smaller but cheaper by 75cents. (which off the top of my head is 20% cheaper ish) If you google the answer and not go for a bad pic.
I havent had a Big mac in donkeys years, i normally grab a Gourmet Angus ^
http://www.businessinsider.com/big-mac-cost-around-the-world-2017-1?IR=T/#-4
But we eat less in portion sizes in everything. The world knows Americans eat heaps.
So we have a Scotch fillet steak which is more expensive here than there.
We have Lamb that is cheaper here than there (im assuming as nobody said otherwise)
We have Milk and bread that is the same price. (which is the BIG one as its a staple)
We have a Big Mac that is 20% smaller but also 20% cheaper so the same price in reality.
And we have a higher min wage (double or more for adults) with penalty rates and allowances. Sounds like our children under 18 get paid more than your adults...
Im glad we cleared all that up.