Earthbag Calculator
Bag count and fill material from wall dimensions.
About this calculator
Bags Required comes from Courses (wall height divided by layer height) times Bags per Course (wall perimeter divided by bag length), so Wall Perimeter, Wall Height, Bag Length, and Layer Height each pull real weight -- but Bag Width does not. It's a useful number for your own wall-thickness planning (a wider filled bag makes a thicker wall), yet the calculator's bag and fill quantities never actually reference it in the math: entering 18 in or the 30 in maximum produces identical Bags Required, Fill Material, Barbed Wire, and Courses. Fill Material assumes each tamped bag holds about 1 cu ft of fill, so it tracks Bags Required directly.
Barbed Wire -- laid between every course for inter-bag friction -- scales with both Courses and Wall Perimeter, since two strands run the full perimeter at every course line. At the default 30 ft perimeter, 8 ft wall height, and a 30 in bag length with a 5 in tamped layer height, that's 264 bags (with 10% waste), about 9.8 cu yd of fill, 1,200 ft of barbed wire, and 20 courses. The calculator doesn't account for bag overlap at corners or the extra courses a curved (round or oval) footprint typically needs versus a straight-wall layout.
Inputs
Results
Bags required
264
How to Use This Calculator
- Enter Wall Perimeter (ft), Wall Height (ft), and your Bag Length and Width (inches).
- Set Layer Height (in) — typically the compressed bag height after tamping.
- Enter Waste % for damaged or misshapen bags.
- Review Bags Required to order polypropylene bag stock.
- Plan fill material (gravel, clay-sand, or soil) volume based on bag count and dimensions.
How the result changes with Wall perimeter (ft)
| Wall perimeter (ft) | Bags required |
|---|---|
| 15 | 132 |
| 23 | 220 |
| 45 | 396 |
| 75 | 660 |
What each input means
- Wall perimeter (ft)
- Total perimeter of the earthbag structure.
- Wall height (ft)
- Height of the finished wall.
- Bag length (in)
- Length of each polypropylene bag when filled.
- Layer height (in)
- Height of each tamped bag course.
- Bag width (in)
- Width of filled bag for your own wall-thickness planning — not used in the quantities below, which are driven by bag length and layer height.
- Waste %
- Extra bags for tears, corners, and shaping.
What each result means
- Bags required
- Total polypropylene bags needed including waste.
- Fill material (cu yd)
- Volume of fill soil or gravel needed.
- Barbed wire (ft)
- 4-point barbed wire for inter-course bonding (2 strands).
- Courses
- Number of bag courses to reach wall height.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersWall perimeter (ft) = 30, Wall height (ft) = 8, Bag length (in) = 30, Layer height (in) = 5 = 6 input(s) provided
- Calculate Bags requiredBags required = ceil(totalBags * (1 + wastePct / 100))264 = 264
- Calculate Fill materialFill material = round((withWaste * 1.0) / 27 * 100) / 1009.78 = 9.78
- Calculate Barbed wireBarbed wire = round(courses * wallLength * 2)1200 = 1200
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Does bag width change the number of bags or fill material needed?
No -- despite the field's description, Bag Width is never referenced in the calculation. Bags Required, Fill Material, Barbed Wire, and Courses are driven entirely by Wall Perimeter, Wall Height, Bag Length, and Layer Height; use bag width only for your own wall-thickness planning.
What determines how many courses of bags a wall needs?
Wall Height divided by Layer Height (the compressed height of each tamped course), rounded up. At the default 8 ft wall height and 5 in layer height, that's 20 courses -- shorter layer heights (more tamping per course) increase the course count for the same finished wall height.
How is the barbed wire quantity calculated?
Two strands of barbed wire run the full wall perimeter at every course line, so Barbed Wire equals Courses times Wall Perimeter times 2. At the default 20 courses and 30 ft perimeter, that's 1,200 linear ft.
How much fill material does the waste percentage add?
Waste % inflates Bags Required before Fill Material is calculated from it, since fill is estimated at about 1 cu ft per bag -- at the default 10% waste, a wall needing 240 bags at zero waste instead needs 264, and fill material scales up by the same proportion.
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