Anyone good at maths?!!

First thing to realise is that these beds will need a lot of topsoil/compost.
I did a quick calculation and came up with the following:
Volume of bigger beds 180x60x30 = 324000 cubic cm or 324 liters. x4= 1296 l.
Smaller beds 120x30x30=108000 cubic cm or 108 liters. x2= 216 l.
Total volume needed 1296 + 108 = 1512.
70% topsoil 1512 x0.7 = 1058 or roughly 1000 litres - probably about a metric tonne.
30% manure/compost 1512x 0.3 = 453 l. Probably 1/2 tonne.

Hope this helps! Seems like a lot?

That is so helpful, thanks very much.

Hope my calculations are correct! I don't know where you'll be sourcing your topsoil and compost, but for that amount, it will probably be cheaper to get it by trailerload, rather than bags.

Sorry I couldn't help , the problem brought back the dread I feeling at school with trains travelling at certain speeds and filling baths with a certain amount of water. I am glad someone else could help.

Hi Scentia and Farmor I can help but as the saying goes, I know someone who can (i.e. he has a brain). DHs figures are the same as yours Farmor and he agrees with your totals if that helps ?