Sub-base calculator
Work out how much MOT Type 1 you need, including the allowance for compaction. Loose stone loses roughly a fifth of its volume once it is properly compacted.
Compacted volume in place-
Loose volume to order-
Approximate weight-
Bulk bags (850kg)-
Compaction allowance of 25% is included. Compact in layers of no more than 75mm, not all in one go, or the bottom of the layer never consolidates.
On soft or clay ground, lay a woven geotextile across the formation first. Without it the stone works down into the subsoil and you will be re-stoning in a couple of years.
These figures are a guide for ordering. Site conditions, compaction and wastage vary, so check against your own measurements before placing a large order.