Ballast Calculator
Work out how many tons of ballast you need for a shed base, patio, footing, or concrete mix, based on your project’s area and depth.
Measure straight across the widest point.
Adjust depth below if needed.
Covers spillage and compaction. 5–10% is normal.
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Bags or bulk delivery?
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Coverage & weight
Material profile
For a 200 sq ft base at 6 inches deep, you’ll need about 4.07 cubic yards, or roughly 5.81 tons of all-in ballast including 10% waste. Coarse or all-in ballast suits foundations and concrete mixing; pea shingle drains better under paths.
Ballast needed for common project sizes
These estimates use all-in ballast at 2,850 lb per cubic yard with a 10% waste allowance built in.
| Project | Depth | Cubic yards | Tons |
|---|---|---|---|
| Shed base, 80 sq ft | 4 in | 1.09 yd³ | 1.55 tons |
| Small patio, 144 sq ft | 4 in | 1.96 yd³ | 2.79 tons |
| Footing trench, 45 sq ft | 6 in | 0.92 yd³ | 1.31 tons |
| Garden path, 150 sq ft | 3 in | 1.53 yd³ | 2.18 tons |
| Single garage slab, 400 sq ft | 4 in | 5.43 yd³ | 7.74 tons |
| Foundation strip, 80 sq ft | 6 in | 1.63 yd³ | 2.32 tons |
Ballast types, density and best use
| Type | Weight per yd³ | Best for | Drainage |
|---|---|---|---|
| All-in ballast (sand + gravel mix) | 2,850 lb | Concrete mixing, general fill | Moderate |
| Coarse 20mm ballast | 2,900 lb | Foundations, concrete mixing | Moderate |
| Pea shingle ballast | 2,750 lb | Concrete mixing, bedding | Good |
Figures are for dry material. Wet or freshly delivered material can weigh noticeably more.
How to calculate ballast you need
- Measure the footprint length × width for slabs and shed bases, or trench length × width for footings.
- Pick the depth 3in for paths, 4in under slabs, 6in for footings and foundations.
- Find cubic yards multiply area by depth in feet, then divide by 27.
- Add 10% waste covers compaction and spillage during placement.
- Convert to tons multiply cubic yards by ballast density (2,750-2,900 lb/yd³) and divide by 2,000.
Worked example
Using the calculator’s default 20 ft × 10 ft base at 6 inches with all-in ballast:
- Area20 ft × 10 ft = 200 sq ft
- Depth in feet6 in ÷ 12 = 0.5 ft
- Volume200 sq ft × 0.5 ft = 100 cu ft
- Raw cubic yards100 ÷ 27 = 3.70 yd³
- Plus 10% waste3.70 × 1.10 = 4.07 yd³
- Weight (all-in ballast, 2,850 lb/yd³)4.07 × 2,850 ÷ 2,000 = 5.81 tons
- Order amountRound up to 6 tons to match typical delivery increments
Recommended depth by project
| Project | Recommended depth | Notes |
|---|---|---|
| Project type | Depth | Notes |
| Garden path base | 3 in | Adequate for foot traffic only |
| Shed or slab base | 4 in | Standard under a concrete slab on grade |
| Patio base | 4 in | Compact before pouring concrete or laying pavers |
| Footings / strip foundations | 6 in | Compact in two lifts if hand-tamping |
| Driveway sub-base | 6-8 in | Use coarse or all-in ballast, not pea shingle |
Bags or bulk delivery?
Bagged ballast (typically 50 lb bags) runs several times the per-ton cost of a bulk load, so it’s really only worth it for very small footings or repairs. Past roughly half a ton, bulk delivery plus the flat delivery fee wins on cost and saves you carrying dozens of bags.
- Small jobsunder 0.5 ton (about 20 bags) — bags avoid paying a delivery minimum for a small footing or repair.
- Medium jobs0.5 to 2 tons — compare total bag cost to bulk plus the delivery fee; the two are often close.
- Large jobsover 2 tons — bulk delivery is cheaper and far less labor than stacking bags.
Common mistakes
- Using pea shingle in a concrete mixrounded pea shingle interlocks less than angular coarse ballast and can weaken the cured mix — use coarse or all-in ballast for structural pours.
- Confusing regional meanings of "ballast"some suppliers use ballast to mean coarse aggregate only, not a sand-gravel mix; confirm which product you’re getting before ordering for concrete.
- Not screeding to depthballast beds under slabs need a level screed, not just a dumped and roughly leveled pile.
- Skipping the damp-proof membraneforgetting a DPM over compacted ballast before pouring a slab lets moisture wick up through the concrete.
- Under-ordering for mix ratiosconcrete needs roughly twice the volume of aggregate as cement in a standard mix; miscalculating the ratio leads to running short mid-pour.
- Ignoring drainage under a basepoorly compacted or graded ballast under a slab can hold water; ensure adequate fall away from structures before placing it.
What this calculator assumes
Adjust your result if your project differs from these.
- Depth is the compacted thickness of the ballast layer.
- Density reflects damp, compacted bulk density typical of quarried ballast.
- 10% waste covers compaction settlement and spillage during spreading.
- Bedding-depth figures apply to base and footing uses; concrete mix-ratio volumes are covered by the Ballast for Concrete calculator.
- Prices are material only; delivery and compaction equipment are extra.
- Bag coverage assumes standard 50 lb bags.
Common questions
What is ballast used for?
Ballast is a sand-and-gravel or crushed-stone mix used to bed shed and slab bases, backfill footings, and as the coarse aggregate in concrete mixes.
What's the difference between ballast and gravel?
“Ballast” usually refers to an all-in mix of sand and stone up to about 20mm, while “gravel” often means washed, uniform stone with the fines screened out. Ballast is denser and better for concrete and compacted bases.
How much ballast do I need for a concrete mix?
For a standard 1:2:4 (cement:sand:aggregate) mix, ballast makes up roughly 4/7 of the total mix volume — use the Ballast for Concrete calculator to size a specific pour.
Can I use pea shingle instead of coarse ballast?
For bedding and general fill, yes. For concrete mixing or foundations, coarse 20mm or all-in ballast interlocks better than rounded pea shingle.
How deep should ballast be under a shed base?
4 inches compacted is standard for a timber or resin shed base; go to 6 inches under a poured concrete pad.
How many tons is a cubic yard of ballast?
About 1.375 to 1.45 tons, depending on grade — all-in ballast runs 2,850 lb/yd³, coarse 20mm about 2,900 lb/yd³, and pea shingle about 2,750 lb/yd³.
Does ballast need to be compacted?
Yes. Compact in 2-4 inch lifts with a plate compactor; uncompacted ballast settles unevenly under a slab or paving.
What's the difference between all-in and washed ballast?
All-in ballast includes the natural sand and fines from the pit; washed ballast has those fines removed for cleaner, better-draining fill.
Can I lay pavers directly on ballast?
No. Pavers need a bedding sand layer (about 1 inch) screeded on top of a compacted ballast or aggregate base, not directly on the ballast itself.
Do I need a membrane under ballast for a shed?
On damp or poorly draining ground, a weed membrane or DPM under the ballast helps control moisture and weed growth beneath the base.
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Project
| Shape | — |
| Dimensions | — |
| Depth | — |
| Area | — |
| Material | — |
| Waste allowance | — |
Volume & weight (incl. waste)
| Cubic yards | — |
| Cubic feet | — |
| Weight | — |
| Tons (rounded up) | — |
Shopping list
| Bulk order | — |
| Bagged alternative (0.5 cu ft) | — |
| Estimated cost | — |
Notes
Estimate generated by materialcalculate.com. Assumes uniform depth and standard dry material densities. Confirm quantities with your supplier before ordering.