Wall From the flood guidance you follow

Wall Length m

Wall Height m

Base Width m

Flood guidance sets the base width for a given height; enter the figure yours gives.

Filled Bag Measure a filled, laid and tamped bag

Laid Bag Length along the Wall m

Laid Bag Width across the Wall m

Laid Bag Thickness m

Sand per Bag kg

Loose Sand Bulk Density t/m³

From the supplier, or weigh a bucket of known volume.

Spare Sacks %

Empty Sacks to Order

— sacks

Bags in the wall plus the spare share, rounded up

Count

Layers: — layers
Bags along the Wall per Row: — bags
Bags in the Bottom Layer: — bags
Bags in the Wall: — bags
Bags per Metre of Wall: — bags/m
Sand: — t
Sand Volume (Loose): — m³

The base width, the laid size of a bag and the sand per bag are yours; flood guidance differs on the base-to-height ratio and on how full a bag should be, and the tool has no figure of its own for either. Each layer is one laid bag thick and the wall narrows evenly from the base width to a single bag width on top; every row is counted in whole bags along the wall and across it, so a short wall rounds up at each end. Bonding, the trench some guidance asks for under the first layer, and plastic sheeting are not counted. **This is a material count, not a flood defence design: a sandbag wall seeps and must be built and watched as your flood authority advises.**

Sandbag Flood Wall: Layers, Bags per Layer, Sand Tonnage & Woven Sacks to Order — free, with the formula and a worked example, at Textile School.