🏗️ Free Base Calculator
Gravel Base Calculator — Shed, Patio & Sub-Base
Calculate the exact amount of compacted gravel base material for shed foundations, patio bases, and road sub-bases. Accounts for compaction factor and waste. Instant results.
✅ Compaction Factor ✅ Shed Foundations ✅ Patio Bases ✅ Road Sub-base ✅ Weight in Tons
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Frequently Asked Questions
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For a standard shed base, excavate 4–6 inches deep, fill with compacted crusher run gravel. Calculate: Length × Width × Depth (ft) ÷ 27 × 1.30 compaction factor. For a 12×16 ft shed at 6 inches: 12 × 16 × 0.5 ÷ 27 × 1.30 = 4.62 cubic yards. Add 15% waste to order 5.3 cubic yards. The gravel base should extend 6 inches beyond the shed footprint on all sides.
Crusher run (#411 or processed gravel) is the best material for shed foundations because it contains stone fines that bind and compact tightly. Dense Grade Aggregate (DGA) is another excellent option. Avoid clean washed gravel for foundations as it does not compact well. The goal is a solid, stable base — angular material with fines achieves this.
A standard concrete or paver patio needs a 4-inch compacted gravel base. For soft or clay soils, increase to 6 inches. For a flagstone patio, 2–3 inches of crushed stone plus 1 inch of sand is standard. The gravel base is critical — skipping or undersizing it causes settling, cracking, and heaving over time.
Gravel compacts when weight is applied — loose material takes more volume than its final compacted state. A 1.30× compaction factor means you order 30% more material than the calculated net volume to account for this. For structural base applications (foundations, sub-bases), always use a compaction factor of 1.25–1.35× depending on material type and required load bearing.
Crusher run gravel for a base typically costs $30–$50 per cubic yard. A 12×16 ft shed base at 6 inches deep needs approximately 5.3 cubic yards = $160–$265 in material plus $50–$150 delivery. Total cost for a shed gravel base is typically $200–$400. For larger areas like a driveway sub-base, see our gravel driveway calculator for a complete estimate.
Gravel Base Requirements by Project Type
A properly compacted gravel base is the foundation of any long-lasting outdoor structure. Skimping on base depth or material quality leads to settling, cracking, and expensive repairs. Our calculator uses compaction factor × net volume to give you the correct material order quantity — not just the theoretical net volume.
| Project | Base Depth | Best Material | Compaction |
|---|---|---|---|
| Shed foundation | 4–6 in | Crusher run | 1.30× |
| Paver / brick patio | 4–6 in | Crushed stone + sand | 1.25× |
| Concrete patio slab | 4–6 in | Crushed stone #57 | 1.25× |
| Flagstone patio | 2–4 in | Crushed stone + sand | 1.20× |
| Concrete driveway base | 4–8 in | Crusher run | 1.30× |
| Retaining wall base | 6–12 in | Crushed stone | 1.30× |
| Road / heavy vehicle base | 8–12 in | Limestone base | 1.35× |
| Swimming pool base | 4–6 in | Sand + gravel | 1.25× |
How to Properly Install a Gravel Base
- ▸ Excavate to correct depth: Remove topsoil and organic material to your required depth plus 2 inches for the sand setting bed. A bobcat or mini-excavator rental saves hours of manual labor.
- ▸ Check for soft spots: After excavation, walk the subgrade and probe for soft spots. Fill with additional base material and compact before adding your main base layer.
- ▸ Compact in 3–4 inch lifts: Never add all your base material at once. Compact each 3–4 inch layer with a plate compactor before adding the next. This is critical for structural integrity.
- ▸ Check for level and drainage: Use a laser level or long spirit level to confirm the base is flat. Slope the base 1/8 inch per foot away from structures for water drainage.
- ▸ Test with foot pressure: A properly compacted gravel base should show no deformation under foot pressure. If it does, compact again or add a lift of material to stabilize.
For driveway gravel calculations, use our gravel driveway calculator. To calculate all gravel types for any shape, see the main gravel calculator.