How much fine gravel do I need

[Grandad99]

One 30ft x40 inch side border was laid with black weedproof mesh fabric topped with fine gravel. It contains only a row of smallish conifers and over the years the dropped needles and airborne bits have enabled weeds to now take root in the gravel.

I want to remove and replace both the mesh fabric and gravel. No problem working out the amount of mesh needed but how much gravel will I want for a depth of 2 inches?

[welsh brickie]

if you get a 1ton bag delivered you should have plenty,