Sandbag Calculator

USACE planning table used by this calculator

This estimate uses the bag quantities published in the U.S. Army Corps of Engineers, St. Paul District, Flood Fight Handbook (2022). The requested height rounds up to the next listed tier. That conservative lookup is not interpolation. For the applied tier:

base bags = barrier length in feet × bags per linear foot

reserve bags = base bags × reserve percentage, rounded up to a whole bag

total fill weight = total bags × fill per bag

USACE also illustrates a base approximately three times the barrier height. That is a planning footprint, not a structural design:

base width ≈ 3 × barrier height

For the canonical exact example, a 100 ft run at 1 ft, with 40 lb per bag and a 10% reserve, needs 600 base bags plus 60 reserve bags, or 660 bags total. Their planned fill weighs 26,400 lb, equal to 13.2 US short tons. The approximate 3 ft base width gives a 300 ft² footprint, before working and access space.

Why official estimates can disagree

USACE publications do not all contain the same table. A 2007 USACE flood-fight handbook lists 5, 10, 21, 36 and 55 bags per linear foot for the same nominal 1-to-5-foot heights, while the named 2022 handbook uses 6, 21, 45, 78 and 120. Different editions and barrier configurations can embody different placement and geometry assumptions. Do not blend the tables or silently substitute one for another. This calculator identifies and applies the fixed named table above so its result can be reproduced.

The rows are discrete configurations. A 2.5 ft request uses the 3 ft row; the tool does not interpolate a new rate and does not extrapolate above 5 ft. The selected tier is disclosed in the result. Ask the responsible flood authority or a qualified engineer about any site outside the published configuration.

Limits that a bag count cannot solve

Sandbag barriers are temporary and are not watertight. Water may seep through, over, under or around them. The model does not assess erosion, undermining, corners, tie-ins, safe height, freeboard, drains or whether diverted water will harm another property. Never delay an evacuation to build or defend a barrier. Alerts and emergency instructions take priority.

Floodwater may contain sewage, chemicals, sharp debris and biological hazards. Bags, sand and protective clothing exposed to it may require controlled handling or disposal under local guidance. Filling, lifting and placing thousands of bags also creates serious manual-handling risk. OSHA recommends mechanical help where possible, team lifting for heavy loads, suitable gloves, eye protection and protective footwear. A quantity estimate does not replace an emergency plan, a site assessment or safe-work controls.

Sources: USACE St. Paul District Flood Fight Handbook (2022), USACE Flood-Fight Handbook (2007), FEMA localized-flooding guidance, CDC floodwater safety guidance, and OSHA sandbagging safety fact sheet.