Gravel Parking Pad Calculator

Gravel parking pad calculator formula

A gravel parking pad calculator takes the pad’s length, width and depth, converts the volume to cubic yards, and multiplies by the weight of the stone. Tons = length × width × (depth in inches ÷ 12) ÷ 27 × 1.4. Cost = tons × your price per ton. The default price is $45 per ton, and a checkbox adds 10 percent for waste.

The formula in plain words

Multiply the two floor dimensions to get square feet. Multiply by the depth in feet, so 6 inches is 0.5. Divide the cubic feet by 27 to get cubic yards. A cubic yard of this gravel weighs about 1.4 tons, so multiply by 1.4 to get the number you tell the quarry.

Worked examples

These match the calculator exactly.

1. One car pad: 20 ft × 12 ft, 6 in deep, $45 per ton

• Area: 20 × 12 = 240 sq ft
• Volume: 240 × 0.5 = 120 ft³ ÷ 27 = 4.44 yd³
• Tons: 4.444 × 1.4 = 6.22 tons
• Cost: 6.222 × $45 = $280
• With 10% extra: 6.844 tons, $308

2. Longer, shallower pad: 24 ft × 10 ft, 4 in deep, $45 per ton

• Area: 240 sq ft
• Volume: 240 × 0.3333 = 80 ft³ ÷ 27 = 2.96 yd³
• Tons: 2.963 × 1.4 = 4.15 tons, about $187
• With 10% extra: 4.56 tons, about $205

Both pads cover 240 square feet. The only difference is depth, and depth moves the order from 4.15 tons to 6.22.

Pad sizes and depths

Use	Typical footprint	Common depth
One car	10 × 20 ft	4 to 6 in
One car with door room	12 × 20 ft	4 to 6 in
Two cars side by side	20 to 24 × 20 ft	4 to 6 in
Pickup or van	12 × 24 ft	6 in
Camper or boat	12 × 30 ft or more	6 in or more

Depth values are common practice, not a rule. Soil, drainage and traffic all change what a pad needs.

How to measure the pad

Mark the corners with stakes and string, then measure the string. Put the stakes where the finished edge of the stone will sit, not where the old lawn ends. Make the pad a little wider than the tire track so wheels do not roll off the edge.

If the pad is not a rectangle, split it into rectangles and run each one through the tool. Add the tons together. Curved entrances are easiest to treat as a rectangle plus a triangle.

Preparing the ground

Stone sits on whatever is under it, so the base matters as much as the quantity. Strip the sod and topsoil first, since organic soil compresses and leaves ruts. Slope the subgrade slightly so water runs off the pad instead of pooling. Many installers lay woven landscape or geotextile fabric on soft ground before the stone goes down.

The pad should be compacted in layers if it is deeper than about 4 inches. Compacting in lifts leaves a firm surface. Dumping the full depth at once leaves a soft base that ruts under a heavy vehicle.

Edging and drainage

Loose stone creeps outward under tires, so many pads get an edge of timber, steel or concrete. Edging does not change the stone quantity, but it keeps the 6 inch depth where you put it. Grade the pad so water leaves it, with a gentle fall of a fraction of an inch per foot toward a ditch, lawn or drain. A pad that holds water turns to mud even with good stone.

Common mistakes

• Measuring the old lawn instead of the finished pad. A pad that is 1 foot bigger on every side adds a lot of stone.
• Entering depth in feet. The tool takes inches. Typing 6 for feet would give a number twelve times too big.
• Ignoring compaction. Loose stone packs down, so the first delivery often falls short.
• Using pea gravel. It is rounded and rolls under a tire, so it makes a poor car surface.

Related pages

For a longer drive, see the gravel driveway calculator. If you need a compacted layer under the surface stone, the road base calculator covers it, and the gravel base calculator handles a shared base. The gravel cost calculator adds delivery.