Road Base Calculator

Calculate road base volume from your area and finished compacted depth, with optional supplier compaction or yield figures and bulk density for weight.

Road base volume calculator

Material: Road base · Calculating another material? Use the Gravel Calculator

Units
Area and depth

Section 1

Shape

For a square, enter the same length and width.

Enter the finished depth you plan to use.

Add another area — a second bed or a path, for example — to calculate a combined total.

Compaction / yieldOptional — only if your supplier or project gives a figure
How do you know the adjustment?

Specifications such as “95% maximum dry density” are density-test targets. They do not mean adding 5% more material.

Advanced optionsExtra material / handling allowance

Adds the percentage you choose to the order volume for waste, handling or contingency. It is separate from compaction.

Result

Your result will appear here

Enter your measurements and calculate to see volume in cubic yards, cubic feet, and cubic metres.

How this calculator works

Road base is specified by its finished, compacted depth. The calculator multiplies your area by that depth to get the finished volume.

Finished volume = Area × Finished compacted depth

To estimate the loose material to order, open Compaction / yield and enter the figure your supplier or project specification gives:

Loose volume = Finished volume ÷ (1 − volume reduction)

Loose volume = Finished volume ÷ loose-to-compacted yield

The Extra material / handling allowance, if you add one, is applied after this adjustment.

About road base

Road base is a graded aggregate — a blend of stone sizes with fines — that is placed and compacted to support a surface above it. Product names and specifications vary by region.

Section design depends on the project

How thick a road base needs to be depends on traffic, the ground beneath, drainage and climate. FHWA guidance for rural gravel roads, for example, changes layer thickness with heavy-truck traffic and subgrade support. This calculator does not recommend a depth; use the depth from your plan or specification.

Compaction is supplied by you

There is no universal compaction factor. Engineering targets such as “95% of maximum dry density” describe a density test, not an extra 5% of material. Leave the adjustment off unless you have a figure for your product or project.

Related projects

Building a driveway with several layers? Use the Gravel Driveway Calculator. Under interlocking concrete pavers, CMHA guidance calls for locally approved road-base aggregate or dense-graded aggregate close to ASTM D2940 — the Paver Base Calculator covers base and bedding. For a general volume, use the Gravel Calculator.

Worked example

Example: 30 ft × 20 ft at 6 in finished, supplier yield of 0.85

  1. Area: 30 ft × 20 ft = 600 ft²
  2. Finished volume: 600 × 0.5 ft = 300 ft³ = 11.11 yd³
  3. Loose volume: 11.11 ÷ 0.85 = 13.07 yd³

Result: 13.07 cubic yards loose to order. The depth and yield are example inputs, not recommendations.

Frequently asked questions

How thick should road base be?

It depends on what the base supports and on site conditions. Use the thickness in your plan or specification; the calculator does not supply one.

What is a loose-to-compacted yield?

A figure some suppliers or specifications give for how much compacted volume you get from a loose volume. Loose volume = finished volume ÷ yield.

Can I estimate road base weight?

Yes, with your supplier’s bulk density for the exact product. Make sure the density condition matches the volume — a loose density for the loose order volume.

Sources & methodology

No source supplies a road base depth, compaction factor or density. Sources relevant to this page: