Decorative Stone

[mr_doubtfire]

How many one tonne bags of 20mm gravel will I require to cover 54 sq mtrs of my garden to a depth of approx 40mm?

[rockyracoon]

This website recommends 4 tonnes, it also gives amounts for different sized bags

http://www.gravelmaster.co.uk/GravelMasterCalculator.aspx

[bert_h]

The arithmetic agrees on 4 tons, but there's an awkward discrepancy between the 40 mm depth you want and the 20 mm gravel size you're getting. After the first layer on the ground, a complete second layer will settle into its gaps, so it will only be about 33 mm, but would still need a bit more than 3 tons. Then with 5 tons you would have enough for a third layer in the gaps of the second, but that would increase the depth to about 50 mm. Maybe you should think about the next smaller size of gravel so that your 4 tons will spread evenly and give you the depth you want.

[The Builder]

Bert has reminded me that 20mm chips do give quite a coarse finish.
Spread the 4 bags of 20mm, let it settle or roll it, then spread a bag of 10mm over the whole lot.

I think it's a nicer finish. All a matter of personal preference though.