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How Much Road Base for a 12x75 Driveway?

A 12 by 75 foot driveway is 900 square feet. How much road base for a 12x75 driveway depends on depth: at 4 inches it is about 11.11 cubic yards or 16.7 tons. Suppliers usually sell by the ton, so the tonnage is the number to give them.

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The math for a 12x75 driveway

  1. Area: 12 × 75 = 900 sq ft.
  2. Depth in feet: 4 ÷ 12 = 0.333 ft.
  3. Cubic feet: 900 × 0.333 = 300.0 cu ft.
  4. Cubic yards: ÷ 27 = 11.11 yd³.
  5. Tons: × 1.5 = 16.7 tons.

The volume and tonnage calculator does this for any size.

Road base needed by depth

DepthCubic yardsTons (approx.)Tons +10%
4 in11.1116.718.3
6 in16.6725.027.5
8 in22.2233.336.7

About road base

Road base is meant to be compacted at close to the right moisture. Dry base rock does not lock up well; a light spray of water before rolling helps. Weight per yard is a planning number; the scale ticket at the yard is the real one.

Preparing the driveway

Strip sod and soft topsoil, grade for drainage and compact the subgrade before any stone goes down. Gravel drives last longer with a compacted base layer under the top stone and a slight crown so water runs off. This driveway sees car and truck traffic, so match the depth to that load rather than to the minimum.

Ordering tips

  • Round up. Compaction and uneven ground eat material. Adding about 10 percent is common.
  • Delivery size. 18.3 tons may take more than one typical dump truck load; small loads may carry a delivery fee. See how many tons of gravel in a dump truck.
  • Bulk vs bags. At this size bulk delivery is usually the practical choice.
  • Where it drops. Have the truck dump as close to the driveway as firm ground allows.

Good and poor uses for road base

Works well for:

  • Base under asphalt and concrete
  • Gravel roads and drives
  • Equipment and shed pads

Poor fit for:

  • Drainage layers
  • Decorative surfaces
  • Surfaces that will stay uncompacted

Quick reference numbers

  • Per inch over 100 sq ft: about 0.46 tons of road base (0.31 cubic yards).
  • Per inch over 1,000 sq ft: about 4.6 tons.
  • Another size for comparison: a 12x24 area at 2 inches takes about 2.7 tons.
  • Weight used here: about 1.5 tons per cubic yard.

Where estimates go wrong

  • Forgetting that compaction shrinks loose material. A loose 4-inch spread of a dense-graded stone may finish closer to 3 inches after rolling.
  • Skipping drainage. Water sitting under any surface softens the base and leads to ruts and potholes.
  • Assuming every supplier uses the same weight. Two yards selling the same product name can quote different tons per yard.
  • Ignoring the base. A thin surface layer over soft soil fails early no matter how much material is on top.

Questions people ask

How many tons of road base for a 12x75 driveway?

About 16.7 tons at 4 inches deep, or 18.3 tons with 10 percent extra.

How many cubic yards is a 12x75 driveway at 4 inches?

About 11.11 cubic yards.

How much does a cubic yard of road base weigh?

Usually around 1.4 to 1.65 compacted tons, depending on stone size, fines and moisture.

How deep should road base be for a driveway?

The table above shows 4 to 8 inches. Shallower depths suit top dressing; deeper depths suit new installs and heavier use.

How many square feet is 12x75?

900 square feet.

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