Mortar and Concrete Mix by weight

[rac2]

New to site today, so I hope this isn't a regular request. I had a quick look through a couple of the forums but couldn't see a post relating to this.
I know the mix ratio's by volume (shovel fulls) but you buy bags of mortar/balast/sand by weight. Last year when I laid the foundations for my garden walls I tried to keep a record, but lost count of the times I went back to buy more bags of cement!
This summer I want to build the walls and cast in some concrete steps.
Can anybody help me with the above info please, to cut down on my trips to the suppliers?
Thanks in advance...

 

[^woody^]

Yes, you buy sand etc by weight, but the bags contain more or less the same amount

Just do it by volume and ignore if one material is wetter than the other.

You don't need exact mix ratios by weight except for large specialised engineering projects.

If you have ordered the materials based on ratios for the volume needed, and then mixed it by adding the materials correctly, then you should not be needing to go and fetch more stuff.

 

[rac2]

Thanks Woody.
It was only for ordering that I needed the info. I will still mix by the shovel full.

 

[^woody^]

Just convert the ratio of whatever mix it is into bags - but check what size bags the merchant sells - may be 20,25 or 40 kg bags for sand/gravel etc.

Or 6-8 25kg cement per 1 tonne bulk bag