A 3/4 crushed stone calculator needs to account for a detail most people overlook until after delivery: "3/4 inch" describes the stone's size not whether it drains well or compacts tight. That second choice washed or unwashed can matter just as much as getting the quantity right.
This guide covers how to calculate your quantity why the washed versus unwashed decision affects performance & where this particular size shows up most often. For a broader look at the standard gradation number this size usually falls under our 57 stone calculator covers that classification in detail.
Key Takeaways
3/4 Inch Describes a Size Not a Formal Grade
Stone sold as "3/4 inch" commonly falls under the #57 gradation classification though the exact range can shift slightly by supplier.
Washed & Unwashed Versions Perform Differently
Washed stone has the fine dust rinsed out for better drainage while unwashed stone keeps those fines which helps it compact into a tighter more stable base.
Weight Sits in a Fairly Consistent Range
A cubic yard of 3/4 crushed stone typically runs 1.2 to 1.5 tons though unwashed material with fines can land slightly heavier.
The Right Choice Depends on the Job
French drains & visible surfaces generally call for washed stone while buried base courses usually do better with unwashed material.
3/4 Inch Is a Size Not a Formal Grade
Stone suppliers describe products two different ways & it helps to know both. A size description like "3/4 inch" refers to roughly how large the individual pieces are. A gradation number like #57 refers to a specific standardized particle size distribution used across the industry.
In practice 3/4 inch crushed stone & #57 stone overlap heavily & are often the same product on a supplier's shelf. The size label is just the more common way people search for & talk about it.
If you want the full breakdown of that gradation system including why it matters for drainage applications our 57 stone guide covers it in more depth than fits here. That said the overlap isn't always exact.
Some suppliers use "3/4 inch" loosely to describe anything from #57 up through the slightly finer #67 grade since both produce similarly sized pieces even though their overall distribution differs. If precision matters for your project especially a commercial or spec driven job ask your supplier to confirm the exact gradation number rather than relying on the size description alone.
Calculating Your 3/4 Crushed Stone Order
The volume & weight math for 3/4 crushed stone follows the same sequence as any other aggregate size.
Measure your area in feet splitting an irregular shape into simpler sections if needed.
Choose your depth typically 2 to 3 inches for paths & beds or 4 to 6 inches for a driveway layer.
Convert depth to feet by dividing your inches figure by 12.
Calculate cubic feet by multiplying length width & depth together.
Divide by 27 to convert cubic feet into cubic yards.
Multiply by density typically 1.2 to 1.5 tons per cubic yard to reach your estimated tonnage.
Washed vs Unwashed 3/4 Crushed Stone
This is the decision that shapes how well your project actually performs & it's easy to miss if you only think in terms of size.
Washed stone has been rinsed to remove fine dust & particles leaving more open space between pieces for water to move through freely.
Unwashed stone keeps those fines in place which fill the gaps between larger pieces & help the material lock together into a firmer more compacted base.
French drains & visible surfaces generally call for washed stone since fines can clog a drain or leave dust residue that washes onto nearby surfaces after rain.
Buried base courses like the layer under a driveway or slab typically do better with unwashed material because the added compaction strength matters more than drainage speed.
Cost usually runs higher for washed stone since the washing process is an added production step.
Choosing the wrong version for the job is a common source of frustration. A French drain built with unwashed stone can clog with fines over time while a driveway base built entirely from washed stone can shift & rut because there's nothing filling the gaps to lock it in place.
When in doubt ask the supplier directly which version a given product is since "3/4 crushed stone" alone doesn't specify washing status by default. Some yards stock both versions of the same size under separate product names while others only carry one & expect you to ask for the other as a special order.
Worked Example
Say you're topping a 15 foot by 20 foot driveway section with 3 inches of washed 3/4 crushed stone.
Convert depth to feet: 3 inches divided by 12 equals 0.25 feet. Calculate volume: 15 ft times 20 ft times 0.25 ft equals 75 cubic feet. Convert to cubic yards: 75 divided by 27 equals about 2.78 cubic yards. Apply density: 2.78 cubic yards times 1.35 tons per cubic yard a reasonable figure for washed stone equals roughly 3.75 tons.
Adding a small buffer for spreading & settling brings a practical order to around 4 tons. If your project also includes a garden bed getting a mulch layer the mulch calculator uses the same area & depth approach to estimate mulch quantities for those sections.
Where 3/4 Crushed Stone Works Best
This size shows up across a wide range of projects specifically because it strikes a balance between drainage & stability that finer or coarser stone doesn't manage as well.
Driveway top layers commonly use it for a stable attractive driving surface. Concrete mix production relies on it as a coarse aggregate component. Farm roads & rough terrain paths use it for a durable load bearing surface. Pipe bedding & French drains use the washed version specifically since clean stone keeps the drainage pathway open around the pipe.
Conclusion
A 3/4 crushed stone calculator gets the quantity side of the job done quickly but the washed versus unwashed decision is what actually determines whether the finished project drains well or compacts properly. Matching that choice to the specific job rather than defaulting to whichever is cheaper or more familiar is what separates a project that holds up from one that needs redoing.
FAQs
How Many Tons of 3/4 Crushed Stone Are in a Cubic Yard?
Typically 1.2 to 1.5 tons per cubic yard though unwashed material with fines can run slightly heavier than clean washed stone of the same size.
Should I Use Washed or Unwashed 3/4 Crushed Stone for a Driveway?
Base layers generally do better with unwashed stone since the fines help it compact tightly. A visible top layer can use either though washed stone tends to look cleaner & drain faster after rain.
Is 3/4 Crushed Stone the Same as #57 Stone?
They overlap heavily & are often the same product since #57 is the formal gradation classification that most 3/4 inch stone falls under. The exact range can shift slightly by supplier.
Can I Use 3/4 Crushed Stone for a French Drain?
Yes but use the washed version specifically. Unwashed stone contains fines that can migrate into the drainage pathway over time & reduce the drain's effectiveness.
Why Does Unwashed Stone Cost Less Than Washed Stone?
Washing is an added production step that removes fine dust & particles which increases processing cost. Unwashed stone skips that step making it cheaper though less ideal for drainage focused applications.