postcrete

I'm putting up a fence which will have 3 galvanised steel H posts. Posts are 1850mm long. Supplier site says to install posts 600mm deep. Post dimensions are 125mm x 105mm. I'm wondering how many bags of postcrete I'll need. Would it be 1 bag per post? Bags are 20kg. Instructions only say to...

Hi all does anyone know how much postcrete I would need for a 20litre bucket? Thank you!

Ok I've replaced several 9ft high posts, 4" × 4" into concrete. My gawd it nearly killed me removing the old posts. I've attached a photo of the posts set in postcrete. Now they are in the same position as the ones I removed. 2ft of the posts are buried in 12" diameter holes. I've measured 2.8m...