Road Base Calculator
Road base (3/4 in minus with fines, also sold as base rock, Class 2 base or ABC) is ordered loose by the ton but measured after it has been compacted. Enter the area and the finished compacted depth, and the calculator adds back the volume lost to compaction and returns the loose cubic yards and tons to order. Defaults come from a quarry's product data: about 1.5 tons per cubic yard, and compaction that can cut the delivered volume by as much as 25%.
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Worked example: 50 × 12 ft driveway, 6 in compacted
| Step | Working | Result |
|---|---|---|
| Compacted volume | 50 × 12 × 0.5 ÷ 27 | 11.1 yd³ |
| Loose volume (25% lost to compaction) | 11.1 ÷ 0.75 | 14.8 yd³ |
| Tons | 14.8 × 1.5 | 22.2 tons |
Tons of road base per 100 sq ft
| Compacted depth | Compacted yd³ | Loose yd³ | Tons |
|---|---|---|---|
| 4 in | 1.23 | 1.65 | 2.47 |
| 6 in | 1.85 | 2.47 | 3.70 |
| 8 in | 2.47 | 3.29 | 4.94 |
Figures come from a quarry's product data — Utah Quarry Direct's Roadbase, a 3/4 in minus mix of small rock and fines: “1.5 tons equals approx 1 cubic yard” and “compaction will decrease the volume purchased by as much as 25%.” The table uses the full 25%; if your supplier quotes less, lower the compaction field. Place and compact it in lifts rather than one thick layer.
Building a driveway? The gravel driveway calculator stacks the base and top layers, the crusher run calculator sizes crusher run, a similar dense-graded base, and crushed concrete is the recycled alternative.
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Frequently asked questions
- How much road base do I need?
- Work out the compacted volume (length × width × depth in ft ÷ 27), divide by 0.75 to allow for up to 25% lost to compaction, then multiply by 1.5 tons per yard. A 50 × 12 ft driveway at 6 in compacted is 11.1 yd³ compacted, 14.8 yd³ loose and about 22.2 tons.
- How many tons of road base are in a cubic yard?
- About 1.5 tons, from Utah Quarry Direct's product data ("1.5 tons equals approx 1 cubic yard"). Wetter or denser base weighs more, so check your quarry's figure.
- How much does road base compact?
- The quarry's figure is that compaction decreases the volume purchased by as much as 25%. So 4 yards dumped loose can finish as about 3 compacted yards; order compacted yards ÷ 0.75.
- How many tons of road base for 1,000 square feet?
- About 24.7 tons at 4 in compacted, using 1.5 t/yd³ and a 25% compaction allowance (12.3 yd³ compacted, 16.5 yd³ loose). At 6 in it is about 37 tons.
- Is road base the same as crusher run?
- They do the same job: a dense-graded mix of stone and fines that compacts hard. Names vary by region (road base, base rock, Class 2, crusher run, ABC). The crusher run calculator uses that material's figures, and the crushed concrete calculator covers recycled base.
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