Washed Stone Calculator: How Much Do You Need?

This washed stone calculator works out the volume and weight of washed stone you need for a project. You enter the length, width, and depth of the area to be covered, and it returns the volume in cubic feet and cubic yards, plus the estimated weight in tons. It helps you order the right amount of material for driveways, drainage beds, or landscaping paths.

Formula

The calculator uses the basic volume formula for a rectangular prism:

Volume (cubic feet) = Length (ft) × Width (ft) × Depth (ft)

Because depth is entered in inches, it is first converted to feet by dividing by 12. Then, to get cubic yards, the cubic feet are divided by 27 (since 1 cubic yard = 27 cubic feet). For the weight estimate, the calculator multiplies the cubic feet by 0.105 tons per cubic foot. This factor is an average for washed stone (typically limestone or gravel) with a density of about 105 lb per cubic foot. Different stone types can vary from 90 to 125 lb per cubic foot, so the weight is an estimate, not an exact value.

Worked Example

Using the default values from the calculator: length = 20 ft, width = 10 ft, depth = 4 in.

1. Convert depth to feet: 4 in ÷ 12 = 0.333 ft
2. Calculate volume in cubic feet: 20 × 10 × 0.333 = 66.6 cu ft
3. Convert to cubic yards: 66.6 ÷ 27 = 2.47 cu yd
4. Estimate weight: 66.6 × 0.105 = 6.99 tons

The calculator rounds the volume to 66.6 cu ft, 2.47 cu yd, and 6.99 tons. This matches the example exactly.

When to Use This Calculator

You would use a washed stone calculator when planning any project that requires a layer of clean, screened stone. Common uses include:

• Preparing a base for a paver patio or walkway
• Creating a French drain or trench for drainage
• Laying a new gravel driveway or path
• Backfilling a retaining wall

In all these cases, you need to know how much stone to order. Ordering too little means an extra delivery fee; ordering too much wastes money and creates a storage problem. This calculator gives a solid starting point.

How to Measure Your Project Area

Accurate measurements are key. For a rectangular area, measure the length and width in feet. If the area is not a perfect rectangle, break it into smaller rectangles, calculate each one, and add the volumes together. For depth, decide on the compacted depth you need. A typical paver base is 4 to 6 inches deep, while a drainage trench might be 6 to 12 inches deep. Remember that washed stone compacts about 20% when tamped, so you may need to order extra if you plan to compact it.

Common Mistakes and How to Avoid Them

The most frequent error is mixing units. Always convert inches to feet before multiplying. Another mistake is using the depth of the final surface rather than the depth of the stone layer. For example, if your paver is 2 inches thick and you want the paver top to be 4 inches above the soil, the stone base is only 2 inches thick (4 – 2). Also, be aware that the weight estimate assumes a specific density. If you are using a very heavy stone like basalt, the weight will be higher. Check with your supplier for the exact density of the stone you plan to order.

Washed Stone vs. Other Aggregates

Washed stone is cleaned of dust and fines, which makes it ideal for drainage because water can flow through it easily. It is also used in decorative landscaping because it looks clean and uniform. In contrast, crushed stone with fines (like crusher run) compacts into a solid base but does not drain well. Pea gravel is smaller and rounder, often used for paths, but it shifts more underfoot. The calculator works for any loose aggregate, but the weight factor may change. For pea gravel, the density is similar, but for lightweight materials like lava rock, the weight would be much lower.

Cost Considerations

Washed stone is sold by the cubic yard or by the ton. The calculator gives you both, so you can compare prices. Typically, you will pay more per cubic yard for smaller quantities. Delivery is often a significant part of the cost, so it can be cheaper to order a full truckload (usually 10–15 cubic yards) if you have the space and the project can use it. Prices vary widely by region and stone type, so check with local suppliers. The weight estimate helps you compare a per-ton price to a per-yard price.

Safety and Handling Tips

Washed stone is heavy. A cubic yard of it weighs about 1.4 tons (2,800 lb). Do not try to move it by hand in bulk. Use a wheelbarrow for small amounts, but for large projects, consider having it delivered and placed with a chute or use a small excavator. When spreading stone, wear gloves and safety glasses to protect against sharp edges. If you are working in a trench, be aware of the risk of cave-ins and follow proper trench safety practices. Also, be careful when lifting heavy bags or buckets to avoid back strain.

Frequently Asked Questions

How much washed stone do I need for a 10×10 patio?

For a 10×10 ft area with a 4-inch depth, the calculator gives 33.3 cubic feet, which is 1.23 cubic yards. That is about 3.5 tons of washed stone. This is a typical base for a small patio.

What depth should I use for a driveway?

For a residential driveway, a compacted depth of 4 to 6 inches is common. If you are using a two-layer system, you might put 4 inches of larger stone (e.g., #57) and then 2 inches of smaller stone on top. Always compact each layer.

How many cubic feet are in a ton of washed stone?

At the average density of 105 lb per cubic foot, one ton (2,000 lb) equals about 19 cubic feet. But because density varies, it could be anywhere from 16 to 22 cubic feet per ton. Ask your supplier for the specific weight.

Can I use this calculator for pea gravel?

Yes, the volume calculation is the same. The weight estimate may be slightly off because pea gravel has a similar density to washed stone, but it is often a bit lighter. Use the volume number for ordering, and confirm the weight with your supplier.

What is the difference between washed stone and crushed stone?

Washed stone is crushed rock that has been washed to remove dust and fines. Crushed stone may contain those fines, which help it compact into a stable base. Washed stone is cleaner and drains better, but it does not compact as tightly. For a paver base, you might use crushed stone with fines for the bottom layer and washed stone for the top layer.

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in l | Length | ft | 20 | 0
in w | Width | ft | 10 | 0
in d | Depth | in | 4 | 0
out vol_ft | Volume | cu ft | l * w * (d / 12) | 1
out vol_yd | Volume | cu yd | (l * w * (d / 12)) / 27 | 2
out tons | Estimated weight | tons | (l * w * (d / 12)) * 0.105 | 2