5.4L of detergent in the nice 'sideways' shelved bottle that allows you to just pour from a tap into the lid for washing.
works out at $4.80 per liter
Same thing is $37 in Big W so is a good saving!
the $18 for 4L - https://www.ozbargain.com.au/node/803505 is a bit better 'per liter' at $4.50…but less convenient, the 'big bottle' is really worth the extra.
(it would be $19.20 at the same per liter price as the 5.4l one)
if you're super 'cost efficient' then go for the smaller bottle and refill your larger one!
Don't forget the Subscribe and Save (S&S) - $23.31