Last Updated on July 21, 2023 by Grow with Bovees
When you’re planning to use crushed stone or gravel for a project such as a new driveway, drainage, or a patio, it’s critical you buy the right size that is intended for the job.
For that, you need a handy guide to tell you how big the different grades of gravel and rocks are and what type of function they are best suited for.
Always striving to help our readers out, the team here at Bovees decided to create a comprehensive guide with all the information you need along with a crushed stone and gravel size chart to use as a handy reference.
Let’s jump in!
Crushed Stones vs Gravel – What’s the Difference?
Natural gravel you may have heard of includes river rock, washed river gravel, and pea gravel depending on the size of the stone. Usually found with a rounded shape and a smooth texture, these stones are found in waterside locations such as rivers, lakes, oceans, and geological formations.
Nowadays, ‘gravel’ is also often used to describe all types of manufactured crushed stone and rocks used as aggregate in the construction industry as well as naturally occurring stones.
Aggregate is made by harvesting large rocks and then crushing them using mechanical crushers which can produce various crushed stone grades of different sizes.
Crushed stone is characterized by its angular faces and jagged edges with most aggregate being made from limestone and dolomite. Other rock types often used include granite, trap rock, and sandstone.
Most types of gravel are readily available across the U.S., either in individual 50lb bags or in bulk by the ton, and come in different textures, grades, and colors, so it’s important to do your homework and identify exactly what type and how much you need when planning your project.
Gravel and Rock Sizes and Grades
Crushed rocks and stones are graded according to the size or diameter of individual stones.
The name of each grade may differ depending on your location and can even vary from state to state, so you will always need to check with your supplier, but in general, grading sizes go from 1 to 10 plus several specialized categories.
Usually, the smaller the grade number, the larger, or coarser the stones, although that doesn’t hold true for the specialized grades as you will see.
Of these ten standard crushed stone grades, you will usually only find around five in general use along with a couple of ‘special’ gradings.
We’ve taken a look at the most popular gravel sizes below, along with the places you would use them.
Crushed Stone #1: Approx. 2″-4″ Wide
Crushed stone grade no. 1 is the largest size with diameters ranging from around 2 inches to 4 inches. As this grade contains larger pieces, it’s not suitable for shoveling and stones will need to be moved individually.
Typical uses for gravel #1 include:
- Filling larger holes
- Stabilizing areas with a high risk of soil erosion
- Protecting land from water damage
- Lining rainwater ditches and pits
- As decorative stone around your flower beds or yard
Crushed Gravel #2: Approx 1½ ″ to 3″ Wide
Crushed rocks in grade no. 2 usually range from 1½ inches to 3 inches in diameter, so, depending on your supplier, may contain larger gravel stones that, like #1, are not easy to work with and will need to be moved as individual pieces.
Uses of gravel #2 include the following:
Filling large holes.
- Railroad ballast
- Culvert ballast.
- Decorative purposes with the larger rocks
- Stormwater management systems
- Filter systems for septic tanks
Sub-base for driveways, roads, or highway works needing better stability
Crushed Stone #3: Approx 1″-2½ ″ Wide
Crushed rocks number 3 grade is one of the most popular sizes for homeowners as it can be used for numerous construction projects as a solid foundation.
Stones range from 1 inch to 2½ inches in diameter and typical applications include:
- Driveway base with screening
- Railroad projects
- Drainage projects
- Dry wells
- Septic systems base
Crushed Stones #5: Approx ½” to 1½ ″ Wide
Crushed stone number 5 contains gravel that is usually from around ½ inch up to 1½ inches in size.
This size is mainly used for the following:
- As a road and slab base
- Paved driveway base layer of gravel
- Crushed stone patios
- Drainage projects
Crushed Stones #8: Approx ⅜”- ½″ Wide
Crushed stone number 8 will typically contain ⅜ inch to ½ an inch wide rocks and a common aggregate used for mixing concrete.
Popular uses of number 8 gravel include:
- Concrete mixes
- Asphalt mixes
- Driveways topdressing
- Decorative gravel, as pebbles on top of potted plants, and also landscaping around trees
- Drainage systems
Crushed Stone #10 (Stone dust or screenings): Usually 1/8″ Wide or Smaller
Crushed stone number 10 is the finest grade and is often referred to as dust or rock/gravel screenings. Resembling coarse sand, #10 is produced as a byproduct of the crushing process and has many uses in the construction and landscaping industries:
- Base material for making pavers, concrete blocks, and concrete slabs (precast)
- Leveling agent for a paver base under clay bricks, blocks, patio stones, and concrete pavers
- Added to larger stones to help pack crevices or prevent movement
- Base material for asphalt
- Topdressing for walkways, bike paths, and horse arenas
Crushed Stone #57 – Approx ½“- 1½″ Wide
Crushed stone number 57 is a special grade often made from a blend of stones #5, #6 and #7 with a nominal size of ¾ of an inch, and is widespread and affordable.
It is a popular choice in agriculture, construction, and landscaping as it is large enough to use in load-bearing applications but still allows for drainage.
Common uses include:
- Primary raw aggregate in concrete mix and hot-mixed asphalt
- Road and paver base
- French drains
- Landscaping
- Septic drainage fields
Crushed stone #67: Usually less than 1″ Wide
Crushed stone grade no. 67 is another special grade containing rocks that are less than 1” with an average size of ¾ inch. It is screened to exclude stone dust and pea gravel so that it will not compact and remains workable by hand, making it an ideal construction material and all-purpose gravel.
Some of the uses include the following:
- Backfilling the base of retaining walls
- Base layer under brick, concrete or stone pavers
- Gravel for driveways and walkways
- Base for pipework and culverts
- Drainage work
Crushed stone #411: Less than 1” Wide
Similar in size to #67 stone, crushed rocks graded #411 are less than 1 inch in diameter with an average size of ¾ inch.
However, unlike crushed stone number 67, #411 contains stone dust so that it can be compacted to make a very firm, stable surface or base layer.
Some of its uses include:
- Base for driveways
- Base layer under asphalt parking lots
- In fact, any job that requires a compactable base material.
Standard Natural Gravel Sizes
In the United States, naturally formed gravel grades are often classified using the Wentworth scale (or Udden-Wentworth scale).
Pebble sizes range from finer to very coarse with gravel particle size diameters as follows:
- Fine gravel – approx 0.157 – 0.31 inches
- Medium gravel – 0.31 – 0.63 inches
- Coarse gravel – 0.63 – 1.26 inches
- Very coarse gravel – 1.26 – 2.5 inches
In addition, it categorizes cobbles and larger rocks as having a diameter of 2.5 – 10.1 inches.
There is also an International Standard ISO14688-1:2017 used in Europe and other countries that defines similar categories to size gravel.
Crushed Stone/Gravel Size Chart
| Gravel Size (inches) | Common Name | Suitability for Applications |
|---|---|---|
| Less than 0.25 | Pea Gravel | – Decorative landscaping |
| – Pathways and walkways | ||
| 0.25 – 0.5 | Fine Gravel | – Mixing with concrete or asphalt |
| – Drainage applications | ||
| 0.5 – 1 | Medium Gravel | – Driveways and parking areas |
| – Drainage applications | ||
| 1 – 2 | Coarse Gravel | – French drains and septic systems |
| – Erosion control and stabilization | ||
| 2 – 4 | Riprap | – Slope protection and riverbank stabilization |
| – Large drainage applications | ||
| 4 – 8 | Large Riprap | – Coastal and shoreline protection |
| – Retaining walls and erosion control | ||
| Greater than 8 | Boulder or Cobbles | – Landscaping focal points and accents |
| – Construction of retaining walls and features |
Depending on where you live the definition of gravel may have different meanings as originally it was used to describe small pieces of natural stone that have been formed through natural weathering and erosion by water.
Gravel Size Chart Summary
Whatever your project, from natural gravel driveways to all the other applications for gravel and crushed stone, you will need to make sure you choose the correct size that’s suitable for your job.
We hope our article has given you all the information you need to identify the grade you will be looking for when speaking to gravel retailers, but remember to always check with them exactly how they are categorizing the stone so that you purchase the correct product.
To finish off our piece we have compiled a few of our most frequently asked questions about crushed rocks and gravel below.
Crushed Stone and Gravel FAQs
Where does gravel come from?
There are generally two natural gravel sources as follows:
The beds of natural water sources such as river rock – this is increasingly difficult to find as harvesting it can disrupt the local ecosystems.
Geological formations where gravel has been formed by weathering and erosion – this is the most common source and is obtained using mined gravel pits and quarries.
What is #57 gravel?
#57 crushed stone or gravel is known as a special grade that contains a blend of stones from some other grades with an average size of 3/4 inch.
It’s a very popular type of stone to use as it has multiple uses in construction, landscaping and agriculture including raw aggregate for concrete mixes and hot-mix asphalt, road and paver bases and french drains.
It is often used as a sub base for driveways, pea gravel patios and other landscape features.
67 Stone vs 57 Stone – What’s the difference?
#67 and #57 graded crushed rocks are similar materials but may come in slightly different sizes where #57 gravel can have a maximum size of 1 1/2″ whereas #67 grade is usually less than 1″.
Crushed stone #67 is also screened so that it has no dust making it minimally compactable and suitable for use where you don’t want the stone to compact in any way. This makes it ideal for uses where you need to maintain drainage qualities such as backfilling behind a retaining wall.
What size gravel is best for driveways?
When looking for gravel sizes that will be best on your driveway, remember that stones can vary considerably, especially when using natural gravel.
The best-sized stone to look for is around 3/4 inch in diameter as this is large enough to provide a firm base for vehicles while leaving enough of a gap for drainage between the stones.
Asphalt millings can also be used as an economical material for driveways.
Which is better for a driveway – natural gravel or crushed stone?
When deciding if natural gravel or crushed stones are better for your driveway it’s a balance between what looks best and what is more durable.
Crushed stone has a rough texture and jagged edge that allows it to interlock and resist erosion, making it more durable as a stone driveway. However, with its gray gravel color, it often does not look particularly attractive.
On the other hand, natural stone with its smooth texture and rounded edge looks great but is easily moved around by vehicles.
It’s very much a personal choice on what will work best for your situation.
References;
https://www.iso.org/standard/66345.html
https://mrdata.usgs.gov/geology/state/sgmc-lith.php?text=gravel