Sandbag Flood Protection Guide
How many bags and how much sand, where to get them, filling and placing them safely, what sandbags can’t do, and what to do after a flood.
What size flood barrier do you need?
Units
ft
Measured along the planned barrierBarrier heightVertical height of the finished barrier
ft
in
How to measure
How are the sandbags stacked?
The estimate uses the U.S. Army Corps of Engineers’ St. Paul District pyramid-barrier quantity table. Other configurations can require different numbers of bags.
Your sandbag estimate
66
sandbags
for a 10 ft barrier at the 1 ft reference height · includes 6 extra (10%)
- Base width
- ≈ 2.5 ft 3 bags across at the bottom
- Layers
- 3 about 3 bags per foot of height
- Sand (estimate)
- ≈ 1.3 tons 2,640 lb at 40 lb per filled bag
Extra bags60 from the table + 6 extra = 66
Sandbag barriers are temporary measures and may leak, overtop or fail. This estimate does not assess water pressure, soil conditions, drainage, structural stability or site safety. Follow local emergency-management instructions.
Why height matters
Bags for 10 ft of pyramid barrier at each USACE reference height, before extra bags| Reference height | Cross-section | Base | Bags | vs 1 ft |
|---|---|---|---|---|
| 1 ft | ≈ 2.5 ft | 60 | — | |
| 2 ft | ≈ 5 ft | 210 | × 3.5 | |
| 3 ftGet guidance | ≈ 7.5 ft | 450 | × 7.5 | |
| 4 ftGet guidance | ≈ 10 ft | 780 | × 13 |
Doubling the height from 1 ft to 2 ft takes 3.5 × the bags, because the base has to get wider as the wall gets taller. A single stack three layers high (about 1 ft) takes 30 for the same length.
Everything you need
| Item | Quantity | Price optional | Total |
|---|---|---|---|
| Empty sandbagsTypical woven bags about 14 × 24 in · includes 6 extra | 66 | $ per bag | — |
| Sand2,640 lb at 40 lb per filled bag · roughly 53 bags of 50 lb or 1.02 cu yd · confirm with your supplier | ≈ 1.3 tons | $ per ton | — |
Materials subtotalAdd pricesEnter a bag price and a sand price to see a materials subtotal. Excludes delivery, equipment and labor.
Also plan for
Sheeting size, truck loads, pallets and labor time aren’t calculated. They depend on the method, fill weight, terrain and supplier.
Your plan
Ready to prepare your supplies?
Learn more
How many sandbags do I need for a flood wall?
For a pyramid barrier, the U.S. Army Corps of Engineers table gives about 600 bags per 100 ft at 1 ft high, 2,100 at 2 ft, 4,500 at 3 ft, 7,800 at 4 ft. Height matters far more than length: each extra foot adds three more layers and makes every layer below it wider.14
How wide does a sandbag wall need to be?
In the table’s pyramid, three bags across is about 2½ ft, and each foot of height needs about three more bags across the base. So a 1 ft barrier is about 2.5 ft wide at the bottom and a 3 ft barrier about 7.5 ft. Corps flood-fight manuals also give a rule of thumb of a base about three times the height, so leave room for that footprint.13
How much sand do I need to fill the bags?
It depends on the bag size and how full you fill it. Bags are typically filled one-half to two-thirds full, and extension guidance suggests keeping them to 35 to 40 lb for handling. CalcBrite uses 40 lb as an illustrative weight; change it under Assumptions.24
Questions
How should sandbags be filled and stacked?
Follow official guidance: the U.S. Army Corps of Engineers’ sandbagging sheets show filling, placement and the pyramid method step by step. They call for bags filled one-half to two-thirds full and left untied, laid lengthwise and parallel to the flow, each layer offset by half a bag and pressed down so the bags fit together. Your local emergency-management office may also run filling stations.21
How many sandbags do I need for a doorway or garage door?
For a low barrier in still water, a single stack is enough: no pyramid is needed at 1 ft or less, and the Corps of Engineers says single stacks generally shouldn’t go above three layers (about 1 ft). The St. Paul District gives 300 bags per 100 ft for a single-width course 1 ft high, about 3 bags per foot. So a 3 ft entry door takes about 9 bags (10 with 10% extra) and a 16 ft garage door about 48 (53). Choose “Single stack” above to work out your own.124
Can sandbags prevent all flooding?
No. Sandbag barriers are temporary. The Corps of Engineers says sandbagging doesn’t guarantee a watertight seal: barriers can leak, be overtopped or fail. Follow local emergency instructions.13
Where can I get sandbags?
Many towns give out empty bags and sand during flood warnings; check your local emergency-management office. Hardware stores and landscape suppliers also sell bags and sand. Availability varies, especially during an emergency.
Landscaping project? The Sand Calculator works out bulk sand by volume for patios and paths. It doesn’t count flood-barrier bags.
How we calculate, assumptions & sourcesSource table, formulas, assumptions, worked example, units and 5 sources
Source table: pyramid barrier, bags per 100 linear feet
| Reference height | Bags per 100 ft | Bags per ft | Layers | Bags across the base | Base width |
|---|---|---|---|---|---|
| 1 ft | 600 | 6 | 3 | 3 | ≈ 2.5 ft |
| 2 ft | 2,100 | 21 | 6 | 6 | ≈ 5 ft |
| 3 ft | 4,500 | 45 | 9 | 9 | ≈ 7.5 ft |
| 4 ft | 7,800 | 78 | 12 | 12 | ≈ 10 ft |
The table is a stacked pyramid: about 3 bags high per foot, a base 3 bags wide per foot of height (3 bags ≈ 2½ ft), and 1 bag ≈ 1 ft along the barrier.12 A single-width course takes 300 bags per 100 ft at 1 ft high, the figure the single-stack option uses.1 It stops at 4 ft; taller barriers aren’t calculated. The Corps gives 3 ft as the preferred height limit for sandbag levees.3
Worked example: 10 ft long, 1 ft 6 in high, 10% extra
- Length 10 ft, height 1 ft 6 in → next whole-foot row: 2 ft
- Table: 2,100 bags per 100 ft → 21 bags per ft
- Bags: ⌈21 × 10⌉ = 210
- Extra 10%: ⌈210 × 0.10⌉ = 21 → 231 bags to plan for
- Sand: 231 × 40 lb = 9,240 lb ≈ 4.6 tons (illustrative fill)
- Base: 2 ft × 3 = 6 bags across ≈ 5 ft
Formulas
- Reference height
- next whole foot at or above the entered height (1–4 ft)
- Bags
- ⌈ table bags per 100 ft ÷ 100 × length (ft) ⌉
- Extra bags
- ⌈ bags × allowance % ⌉
- Layers / base
- 3 × reference height (bags)
- Single stack
- layers = ⌈ height (in) ÷ 4 ⌉, at most 3; bags = ⌈ layers × length (ft) ⌉ (1 bag ≈ 1 ft per layer)
- Base width
- ≈ 2.5 ft × reference height (3 bags ≈ 2½ ft)
- Sand
- total bags × filled-bag weight; ÷ 2,000 = US tons
- Sand to buy
- sand lb ÷ 50 = bags of 50 lb; ÷ 2,590 lb per cu yd (dry loose sand, as in the Sand Calculator) = cu yd
- Metric
- 1 m = 3.28084 ft · 1 kg = 2.20462 lb · 1 tonne = 1,000 kg
Assumptions
- Pyramid barrier per the U.S. Army Corps of Engineers table; other configurations can need different numbers of bags.1
- Whole-foot reference rows only; in-between heights use the next row up. Nothing is interpolated.
- Single stack: one bag wide, up to three layers (about 1 ft), for low barriers in still water; heights use whole layers about 4 in high.124
- Extra bags default to 10%, as in the worked example. Sand to buy is converted at the Sand Calculator’s dry loose sand density; wet sand weighs more, so confirm with your supplier.
- Typical bags about 14 × 24 in, filled one-half to two-thirds full; sand weight uses 40 lb per filled bag (illustrative).24
- No allowance for water pressure, soil, drainage, stability or site safety.
- Not an engineered design, a forecast check, or an evacuation or emergency-response tool.
- All math uses full precision; results are rounded only for display. Unit conversions follow NIST.5
Sources
- Sandbag Levees (brochure, Rev. 08.22), U.S. Army Corps of Engineers, St. Paul District — bags required per 100 linear feet of levee: 1 ft 600, 2 ft 2,100, 3 ft 4,500, 4 ft 7,800; “1 bag length equals about 1 foot, 3 bag widths equals about 2-1/2 feet, 3 bags high equals about 1 foot”; “Single width course requires 300 bags per 100 linear feet, one foot high”; as many rows on the bottom as vertical courses; bags about 24 × 14 inches, filled about two-thirds; “does not guarantee a watertight seal”.
- Sandbagging Techniques (pamphlet, 2004; copy hosted by Utah State University Extension), U.S. Army Corps of Engineers, Northwestern Division — the same 1–4 ft table; bags about 14 × 24 inches, “filled one-half to two-thirds full should generally be left untied”; sand works best, silt, clay or gravel only in emergencies; single stacks “generally not recommended to be above three courses or layers in height (approximately 1 foot)”.
- Flood Response Manual 2023, U.S. Army Corps of Engineers (hosted by the St. Paul District) — 6, 21, 45 and 78 bags per linear foot at 1–4 ft; “5 feet high is the practical limit of a sandbag levee … The preferred height limit is 3 feet”; base width about three times the height; bags filled one-half to two-thirds full; 6 mil polyethylene to improve water tightness.
- Sandbagging for Flood Protection (AE626, reviewed April 2023), NDSU Extension, North Dakota State University — 600, 2,100, 4,500 and 7,800 bags per 100 ft at 1–4 ft; bags about 14 × 24–26 inches and easier to handle at 35 to 40 pounds filled; no pyramid needed at 1 ft or less; support a low wall with “clusters” of bags every 5 feet.
- Guide to the SI, Appendix B.8: factors for units listed alphabetically, NIST Special Publication 811 — foot = 0.3048 m; pound (avoirdupois) = 0.45359237 kg; short ton = 2,000 lb.
- Last reviewed:
- November 2026
- Last updated:
- November 2, 2026
- Calculator version:
- 1.1