How Much Road Base Gravel Do I Need? (Calculator)
You need about 1.7 tons of road base gravel per 100 square feet at a 4-inch compacted depth. This article shows you how to measure, calculate, and order exactly what your project requires.
The short answer
For a 100 sq ft area at 4 inches compacted, you need roughly 1.7 tons of road base gravel. Measure length, width, and depth in feet to find cubic feet, then divide by 27 for cubic yards. Multiply by 1.4 to convert to tons, and order 10% more for waste.
Key takeaways
- Coverage rule: One ton covers about 80 square feet at 2 inches deep.
- Compaction matters: Road base shrinks by about 20% when compacted, so buy extra.
- Cost range: Expect to pay $15 to $30 per ton, as of May 2025.
- DIY-friendly: Spreading gravel is heavy work but doable for most homeowners.
Whether you are building a driveway, patio base, or walkway, road base gravel provides a stable, compacted foundation. Getting the amount right saves money and prevents project delays. This guide covers calculation, costs, and common pitfalls so you order with confidence.
What Is Road Base Gravel and How Much Do I Need?
Road base gravel, also called aggregate base or crushed base, is a blend of ¾-inch crushed rock and fine particles. This mixture locks together when compacted, creating a stable, load-bearing layer. For a typical driveway, you need a 4-inch compacted layer.
- Typical depth: 4 inches for driveways, 2-3 inches for walkways or patios.
- Coverage estimate: One ton covers roughly 80 square feet at 2 inches deep or 40 square feet at 4 inches deep.
- Weight range: Road base weighs 1.3 to 1.5 tons per cubic yard depending on moisture and stone size.
- For exact numbers, use our gravel calculator with your project dimensions.
How Do I Calculate the Amount of Road Base Gravel I Need?
Measuring correctly is the most important step. Start by stretching a tape measure across your area to get length and width in feet. Then decide on your compacted depth in inches. Follow these steps to convert dimensions into tons:
- Step 1: Measure length and width in feet. For irregular shapes, break the area into smaller rectangles.
- Step 2: Convert depth to feet: divide inches by 12 (e.g., 4 inches = 0.33 feet).
- Step 3: Calculate cubic feet: length × width × depth in feet.
- Step 4: Divide by 27 to get cubic yards (since 1 cubic yard = 27 cubic feet).
- Step 5: Multiply cubic yards by 1.4 tons per cubic yard to convert to tons.
- Step 6: Add 10-15% extra for compaction and irregularities.
- Try our gravel calculator to do the math instantly.
How Much Does Road Base Gravel Cost Per Ton or Yard?
The final price tag depends on where you buy, how much you order, and delivery distance. As of May 2025, expect to pay $15 to $30 per ton for bulk road base, or $30 to $60 per cubic yard delivered.
- Per ton: Bulk delivery runs $15 to $30, while bagged from a home center costs much more (about $5 to $8 per 0.5-cubic-foot bag).
- Delivery fees: Add $50 to $100 per truckload within a 10-mile radius; longer distances increase costs.
- Quantity discounts: Ordering 10 tons or more can drop the per-ton price to $12 to $25.
- Minimum loads: Many suppliers have a 5-ton minimum for free delivery; smaller loads may cost extra.
- For small projects, use our crushed stone calculator to see if bagged stone is more cost-effective.
What Are Common Mistakes When Ordering Road Base Gravel?
Even a small miscalculation can leave you short on material or with a pile of leftover gravel you cannot return. Here is what to watch for:
- Not accounting for compaction: Road base settles by about 20% after compacting. If you need a 4-inch finished layer, order enough for a 5-inch loose layer.
- Measuring incorrectly: Irregular shapes often lead to underordering. Use our gravel calculator to handle complex areas.
- Ignoring access: Delivery trucks need 10-12 feet of width and solid ground. A wheelbarrow may be needed for tight spots.
- Skipping waste factor: Always add 10-15% extra for curves, spillage, and variations in thickness.
How Does Road Base Compare to Other Gravel Types?
Not all gravel is the same. Road base is engineered for compaction, while other materials serve different roles. Here is how they stack up:
- Road base vs. pea gravel: Pea gravel is decorative and drains well but shifts when walked on. Road base compacts firmly. Use our pea gravel calculator for landscaping projects.
- Road base vs. crushed stone (clean): Clean crushed stone has no fines, so it does not compact as well. It is better for drainage behind walls.
- Road base vs. sand: Sand is too soft for a driveway base and can wash out easily. Road base provides a harder, more durable surface.
- Road base vs. asphalt: Asphalt is a finished surface; road base is the foundation. Use our asphalt calculator for top layers.
Should I Install Road Base Myself or Hire a Pro?
Installing road base yourself can save hundreds, but it is physically demanding. Weigh the sweat equity against the cost of hiring help.
- DIY-friendly if: You have a level area, access to a pickup truck or delivery, and do not mind shoveling and raking.
- Rent a plate compactor: For driveways, rent a plate compactor for about $50-$80 per day (as of May 2025) to achieve proper density.
- Call a pro if: You need more than 5 tons, have poor drainage, or the area is uneven and requires grading.
- Pro installation costs $3 to $8 per square foot including labor and materials, as of May 2025.
- For a simple concrete slab base, our concrete slab calculator can help you estimate materials for the top layer.
| Road Base | Driveway base, compacted | $15-$30/ton |
|---|---|---|
| Pea Gravel | Decorative paths, erosion control | $30-$60/ton |
| Clean Crushed Stone | Drainage, backfill | $25-$50/ton |
| Sand | Underlayment, mortar mix | $10-$25/ton |
Questions this page answers
How deep should road base be for a driveway?
4 inches of compacted road base is standard for driveways. For heavy vehicles or poor soil, go 6-8 inches. Always compact in 2-inch lifts.
How much road base do I need for 100 square feet?
At 4 inches compacted, you need about 1.7 tons (roughly 1.2 cubic yards). Use our gravel calculator for exact numbers.
Can I use road base under a concrete slab?
Yes, road base is an excellent subbase for concrete. It provides drainage and support. Compact it well before pouring.
What is the difference between road base and AB3?
AB3 is a similar aggregate base material, but road base often has a wider range of particle sizes. Check local specs for your area.
Do I need a weed barrier under road base?
Not typically for compacted applications, but for weed-prone areas, a geotextile fabric can help prevent growth through the base.
Can road base be used as a final surface?
It is not recommended; road base is meant to be covered. It can get dusty and muddy. Use decorative gravel or asphalt on top.
How do I compact road base gravel?
Rent a plate compactor and run it over the gravel in 2-inch layers until it is firm and level. Water lightly to reduce dust and aid compaction.
How much does a truckload of road base cost?
A 15-ton truckload typically costs $300 to $500 delivered, as of May 2025. Prices vary by region.
So, how much road base gravel do you need? Multiply your area's square footage by the depth in feet, divide by 27, and multiply by 1.4 to get tons. Always add 10% extra for waste and compaction. Use our gravel calculator to get an instant estimate for your project.