This interactive calculator will help provide a fairly accurate estimate of the top-dressing requirements for an area that is being hollow-tined.
It does not allow for any overlap where the operation is not carried out in straight lines nor where a second hollow-tining may overlap on the holes formed by the first occasion: A small percentage allowance may wish to be allowed for this occurring.
The amount of top-dressing required to completely fill the holes will in practice be slightly less than the figure given due to tines holes closing up slightly and some excavated material falling back into the holes.