Ballast Calculator
A ballast calculator turns length × width × depth into cubic yards (ft³ ÷ 27), then tons at 1.4 t/yd³. A 20 × 10 ft bed 6 in deep needs 5.19 tons of stone.
What your order looks like
One bulk delivery is usually easier than hauling it yourself.
3.70 yd³ · 5.2 tons
50 wheelbarrow trips (2 cu ft each)
7 pickup loads (0.75 ton each)
1 small dump truck load (6 tons each)
Rules of thumb: A wheelbarrow trip is 2 cubic feet of heavy material, about 200 lb, a load most people can push. A pickup load is 0.75 ton, the payload of a full-size half-ton pickup (1,500 lb). A small single-axle dump truck carries about 6 tons.
How much ballast stone you need
A ballast calculator works out the volume of a track bed or heavy-duty stone layer and converts it to the weight a quarry sells. Multiply length × width × depth in feet to get cubic feet, divide by 27 for cubic yards, then multiply by 1.4 tons per cubic yard. Tons = (L × W × depth in ÷ 12) ÷ 27 × 1.4. A 20 × 10 ft section at 6 inches deep needs 5.19 tons.
Tick the 10% box and the allowance is added before the cost is worked out. Quarries quote ballast per ton, so enter that price.
Why ballast is measured this way
Ballast is coarse stone with very few fines, so it never compacts into a solid mass the way crusher run does. The depth you design is close to the depth you place. That makes the volume method reliable: the stone’s open, interlocking structure is the point.
The 1.4 tons per cubic yard figure is a typical loose weight for angular crushed rock of this size. Dense trap rock or granite can run heavier and some limestones lighter, so if the quarry gives a density, scale the result to match.
Worked examples
Example 1: Equipment pad, 20 × 10 ft, 6 in deep, $50 per ton
- Volume: 20 × 10 × 0.5 = 100 ft³ ÷ 27 = 3.70 yd³
- Tons: 3.704 × 1.4 = 5.19 tons
- With 10% extra: 4.07 yd³ × 1.4 = 5.70 tons
- Cost with allowance: 5.704 × $50 = $285.19
Example 2: Short siding or heritage line, 50 ft long, 10 ft wide bed, 10 in deep, $50 per ton
- Volume: 50 × 10 × (10 ÷ 12) = 416.7 ft³ ÷ 27 = 15.43 yd³
- Tons: 15.43 × 1.4 = 21.60 tons
- With 10% extra: 23.77 tons, about $1,188
A 10 ft bed width here includes the shoulders, the sloped stone either side of the tie ends. Measuring only the tie length would leave the shoulders short.
Ballast tons per 100 sq ft by depth
| Depth | Tons per 100 sq ft | Typical use |
|---|---|---|
| 4 in | 1.73 | Roof ballast layer, light pads |
| 6 in | 2.59 | Equipment and tank pads |
| 8 in | 3.46 | Garden and light-rail track |
| 10 in | 4.32 | Industrial sidings |
| 12 in | 5.19 | Heavier track beds |
These figures are net at 1.4 tons per cubic yard. Track depths are set by the railway or engineer, so treat the “typical use” column as a guide only.
Ballast compared with similar stone
| Stone | Approx. weight | Character |
|---|---|---|
| Railway ballast | ~1.4 t/yd³ | Clean, hard, angular; spec-controlled size |
| #2 stone | ~1.4 t/yd³ | Similar size, general construction grade |
| Crushed stone (#57) | ~1.35 t/yd³ | Smaller, about ½ to 1 in |
| Rip rap | ~1.5 t/yd³ | Much larger, for erosion control |
How to measure a ballast bed
- Length: pace or tape the run along the centreline.
- Width: measure the full bed, toe to toe, including both shoulders. For a trapezoid shape, average the top and bottom widths.
- Depth: measure from the prepared subgrade to the top of the ballast, which on track is usually level with the tops of the ties.
- Curves and turnouts: break them into straight sections and add each one.
Common mistakes
- Leaving out the shoulders. On track the shoulders can hold a large share of the stone.
- Placing ballast straight on soft clay. Without sub-ballast or landscape fabric, the stone sinks and fouls with mud.
- Substituting rounded gravel. Round stones roll under load. Ballast must be angular so it locks together.
- Ordering by the cubic yard when the quote is per ton. Convert with the cubic yards to tons calculator if the yard sells both ways.
For working track or loaded structures, have the bed design confirmed by a qualified engineer.
Frequently asked questions
How many tons of ballast do I need?
Multiply length × width × depth (in feet) to get cubic feet, divide by 27 for cubic yards, and multiply by 1.4 tons per cubic yard. A 20 × 10 ft bed at 6 inches is 3.70 yd³, or 5.19 tons, and 5.70 tons with a 10% allowance.
What is ballast stone used for?
Ballast is coarse, clean, angular crushed stone. Its main job is supporting railway track: it spreads the load from the ties, holds them in line, and drains rainwater straight through. The same stone is used under heavy equipment pads, on ballasted flat roofs, and as coarse drainage fill.
How deep is ballast under railroad ties?
Mainline track commonly has around 12 inches of ballast under the ties, sometimes more, while light industrial sidings and garden or heritage lines often use less. The track owner's or engineer's specification sets the actual figure, so use that depth in the calculator.
How is ballast different from #2 stone?
They overlap in size and both weigh around 1.4 tons per cubic yard. Railway ballast is usually held to a tighter specification for hardness, cleanness, and particle shape, while #2 stone is a general construction size used for drainage and construction entrances.
Do I need a filter layer under ballast?
Often, yes. Under years of vibration, coarse stone can punch down into soft clay while fines pump up into the voids. A layer of finer sub-ballast or a geotextile fabric keeps the two apart and preserves drainage.
Should I add waste when ordering ballast?
Yes. A 10% allowance covers an uneven excavated base, stone pushed past the shoulders, and spillage. On a 5.19-ton order that adds about half a ton, bringing it to 5.70 tons.
Estimates only. Verify quantities with your supplier before purchasing.