What is a serving size of grain based foods?

The Australian Government website eatforhealth.gov.au provides the following guidelines about a serve of grain based foods:

Grains

A standard serve is (500kJ) or:

1 slice (40g) bread

½ medium (40g) roll or flat bread

½ cup (75-120g) cooked rice, pasta, noodles, barley, buckwheat, semolina, polenta, bulgur or quinoa

½ cup (120g) cooked porridge

²/³ cup (30g) wheat cereal flakes

¼ cup (30g) muesli

3 (35g) crispbreads

1 (60g) crumpet

1 small (35g) English muffin or scone

*Grain (cereal) foods, mostly wholegrain and/or high cereal fibre varieties