Shed Foundation Gravel Calculator

Calculate gravel for solid, level, long‑lasting shed bases quickly. Handles rectangles, skids, perimeter trenches, and sloped grades easily. Adjust depth, waste factor, compaction, and edge clearance tolerances. See volume, weight, tons, and bag counts instantly. Export results to CSV or PDF for documentation anywhere.

Units

Shed length (ft)

Shed width (ft)

Compacted base depth (in)

Edge margin each side (in)

Site slope drop across base (in)

Difference between high and low sides.

Compaction multiplier (loose/compacted)

Typical 1.10–1.20.

Waste factor multiplier

Adds allowance for spillage and unevenness.

Bulk density (kg/m³)

Crushed stone often ~1600 kg/m³.

Bag size (lb)

Bag size (kg)

Wheelbarrow volume (ft³)

Material price

Results

Effective footprint: 3.962 × 2.743 m
Area: 10.87 m²
Avg compacted depth: 10.2 cm
Avg loose depth: 11.2 cm

Volume: 1.276 m³ (1.67 yd³)
Weight: 2041 kg (4499 lb)
US tons: 2.25 | Metric tonnes: 2.041
Wheelbarrow loads: 16

50 lb bags: 90

25 kg bags: 82

Estimated material cost: —

Based on selected price unit.

Example Data (4" compacted depth, 6" margin)

Shed size (ft)	Area with margin (ft²)	Loose depth (in)	Volume (yd³)
12×8	117	4.4	1.67
10×10	121	4.4	1.73
16×12	221	4.4	3.15
8×6	63	4.4	0.9

Formulas Used

Effective footprint: (L + 2·margin) × (W + 2·margin)
Average compacted depth: depth + slope_drop / 2
Average loose depth: avg_compacted_depth × compaction_multiplier
Volume (m³): effective_area × avg_loose_depth × waste_factor
Weight (kg): volume_m3 × density_kg_m3
Convert: 1 m³ = 35.3147 ft³ = 1.30795 yd³

This model approximates slope as a linear wedge across the base.

How to Use

Select your unit system.
Enter shed length, width, compacted base depth, and margin.
If the site slopes, enter total drop across the base.
Adjust compaction and waste multipliers to your material and tolerance.
Optionally set density, bag sizes, wheelbarrow volume, and price.
Press Calculate, then export CSV or create a PDF report.

FAQs

Common recommendations are 4–6 inches compacted for small sheds. Heavier structures or poor soils may require deeper bases or engineered foundations.

Crushed stone base aggregate often ranges 1500–1700 kg/m³. Ask your supplier for a product‑specific figure for best weight estimates.

A sloped site needs more fill on the low side. We approximate this by adding half the total drop to the compacted depth before compaction and waste factors.

Six inches (150 mm) each side is common to improve edge bearing and drainage. Increase margins for eave overhangs or edging restraints.

No, it assumes granular base only. You can still estimate volume; accessories like geotextile, grids, or edging should be accounted for separately.

Shed size	Typical compacted depth	Edge margin each side
8×6 ft (2.4×1.8 m)	4 in (100 mm)	6 in (150 mm)
10×8 ft (3.0×2.4 m)	4–6 in (100–150 mm)	6–8 in (150–200 mm)
12×8 ft (3.7×2.4 m)	6 in (150 mm)	6–8 in (150–200 mm)
12×16 ft (3.7×4.9 m)	6–8 in (150–200 mm)	8 in (200 mm)

Shed size

Typical compacted depth

Edge margin each side

8×6 ft (2.4×1.8 m)

4 in (100 mm)

6 in (150 mm)

10×8 ft (3.0×2.4 m)

4–6 in (100–150 mm)

6–8 in (150–200 mm)

12×8 ft (3.7×2.4 m)

6 in (150 mm)

6–8 in (150–200 mm)

12×16 ft (3.7×4.9 m)

6–8 in (150–200 mm)

8 in (200 mm)

Material	kg/m³	lb/yd³ (approx)
¾″ crushed stone	1600	~2697
Pea gravel	1500	~2529
Recycled aggregate	1550	~2613

Material

kg/m³

lb/yd³ (approx)

¾″ crushed stone

1600

~2697

Pea gravel

1500

~2529

Recycled aggregate

1550

~2613

Coverage depth	Area per yd³	Area per m³
3 in / 7.5 cm	108 ft²	13.3 m²
4 in / 10 cm	81 ft²	10.0 m²
6 in / 15 cm	54 ft²	6.7 m²
8 in / 20 cm	40.5 ft²	5.0 m²

Coverage depth

Area per yd³

Area per m³

3 in / 7.5 cm

108 ft²

13.3 m²

4 in / 10 cm

81 ft²

10.0 m²

6 in / 15 cm

54 ft²

6.7 m²

8 in / 20 cm

40.5 ft²

5.0 m²

Width × Depth	ft³	yd³
6 in × 4 in	1.667	0.0617
6 in × 6 in	2.500	0.0926
8 in × 4 in	2.222	0.0823
8 in × 6 in	3.333	0.1235
12 in × 4 in	3.333	0.1235
12 in × 6 in	5.000	0.1852

Width × Depth

ft³

yd³

6 in × 4 in

1.667

0.0617

6 in × 6 in

2.500

0.0926

8 in × 4 in

2.222

0.0823

8 in × 6 in

3.333

0.1235

12 in × 4 in

3.333

0.1235

12 in × 6 in

5.000

0.1852

Width × Depth	m³	yd³
150 mm × 100 mm	0.0450	0.0589
150 mm × 150 mm	0.0675	0.0883
200 mm × 100 mm	0.0600	0.0785
200 mm × 150 mm	0.0900	0.1177
300 mm × 100 mm	0.0900	0.1177
300 mm × 150 mm	0.1350	0.1766

Width × Depth

m³

yd³

150 mm × 100 mm

0.0450

0.0589

150 mm × 150 mm

0.0675

0.0883

200 mm × 100 mm

0.0600

0.0785

200 mm × 150 mm

0.0900

0.1177

300 mm × 100 mm

0.0900

0.1177

300 mm × 150 mm

0.1350

0.1766

Shed Foundation Gravel Calculator

Results

Example Data (4" compacted depth, 6" margin)

Formulas Used

How to Use

FAQs

Recommended Base Depth by Shed Size

Gravel Density & Coverage Quick Reference

Perimeter Trench – Fast Volume Add‑On

Per 10 ft of trench

Per 3 m of trench

Related Calculators

Results

Example Data (4" compacted depth, 6" margin)

Formulas Used

How to Use

FAQs

What depth is recommended for a shed base?

What density should I use?

How does slope affect the calculation?

What margin beyond the shed footprint is typical?

Does the calculator include geotextile or paver base grids?

Recommended Base Depth by Shed Size

Gravel Density & Coverage Quick Reference

Perimeter Trench – Fast Volume Add‑On

Per 10 ft of trench

Per 3 m of trench

Related Calculators