Our gravel calculator works out how many tonnes or 25kg bags of gravel, chippings, or decorative stone you need for a driveway, path, or garden area. Enter the length, width, and desired depth of the gravel layer, and the calculator gives you the volume in cubic metres and the weight in tonnes. For driveways, a depth of 50–75mm is typically recommended; for decorative garden areas, 25–50mm is usually sufficient. The calculator also estimates the number of bulk bags (typically 850kg each) or 25kg bags you would need to order.