🔨

Sandbag Calculator

Estimate how many sandbags you need for a flood barrier (pyramid levee) of a given length and height, the base width, the tonnes of sand to fill them and bags per metre or foot.

Units

Barrier length (m or ft)

Barrier height (m or ft)

Loading calculator…

How it works

cross-section = height × (3 × height + 0.3 m) ÷ 2 · bags = length × cross-section ÷ 0.0094 m³ (⅓ ft³ per half-filled bag) · sand = bags × 0.0094 m³

The US Army Corps of Engineers method stacks sandbags in a pyramid whose base is three times its height and whose top is about one bag (30 cm, 1 ft) wide. Each standard 14 × 26 in (35 × 65 cm) bag, filled one-half to two-thirds and flattened, occupies about one-third of a cubic foot (9.4 L) — which reproduces the USACE planning figures of 600 bags per 100 ft of a 1 ft levee, 2,100 for 2 ft and 4,500 for 3 ft. A filled bag weighs about 15–18 kg (35–40 lb). Lay a plastic sheet on the water side, stagger the joints and tamp each bag into place.

Worked example

A 10 m barrier, 0.6 m high: cross-section = 0.6 × (1.8 + 0.305) ÷ 2 = 0.631 m², volume 6.31 m³, so 6.31 ÷ 0.0094 = 669 sandbags (66.9 per metre) on a 1.8 m base, holding about 6.31 m³ or 10.1 t of sand.

Sources: US Army Corps of Engineers — Sandbagging for flood protection (Northwestern Division) · FEMA — Protect your property from flooding

Frequently asked questions

How many sandbags do I need per metre?

For a pyramid levee about 19 bags per metre at 30 cm high, 67 at 60 cm and 143 at 90 cm. A single doorway barrier two or three bags high needs far fewer.

How much sand fills one sandbag?

Fill bags only half to two-thirds full — about 15–18 kg (35–40 lb) of sand, roughly 9–10 litres — so they can be flattened and overlapped into a tight wall.

How high should a sandbag wall be?

About 30 cm (1 ft) above the expected flood level. Pyramid levees over about 1 m (3 ft) take a great many bags and should be built with expert advice.

How many tonnes of sand per 100 sandbags?

About 1.5–1.8 tonnes, or roughly 1 m³ of sand per 100 bags.

Related calculators

Sand Calculator

Sand for a paver base, sandbox or fill: cubic yards, tons and bags for rectangles, circles, triangles, rings or a list of areas, with sand-type densities, extra for compaction, bulk vs bag cost and truckloads.

Rain Garden Size Calculator

Size a rain garden or bioretention bed from the roof or paved area draining to it, soil type and ponding depth — surface area, volume captured from a design storm, dimensions and drain-down time.

Compacted Fill Calculator

Find how much loose fill (earth, clay, sand, gravel or crushed stone base) to order for a compacted layer: compaction factor, loose m³ or yd³, tonnes and truckloads.

Gabion Calculator

Count the gabion baskets for a wall or revetment and the tonnes of stone fill: box size, layout along, across and up, gabion volume, filled density from porosity and the geotextile behind the wall.

French Drain Gravel Calculator

Estimate the drainage gravel for a French drain trench — cubic yards and tons after subtracting the perforated pipe.

This calculator is for educational purposes. Double-check important results before acting on them.