Gravel Aggregate Calculator – Hardcore, Bags & Cost
Gravel Aggregate Calculator – Hardcore, Bags & Cost
Estimate area, material volume, compaction and extra allowance, approximate weight, bags or loose material, plus optional job costs.
1. Project Setup
Choose your measurement system and currency, then give the estimate an optional project name.
2. Material
Choose a material preset or enter your own density. Preset densities are approximate and should be checked against your supplier where possible.
3. Areas & Depths
Add each part of the project separately. Every area can have its own shape and material depth.
4. Allowances
Compaction and extra/waste are kept separate so you can see exactly what is being added.
5. How Will You Buy the Material?
Choose the option that matches your supplier. You can calculate quantity only if you do not need a material cost.
Your Gravel / Aggregate Estimate
Project Summary
Area-by-Area Breakdown
What to Order
Job Pricing
How This Is Calculated
Turn Your Estimate Into a Professional Quote or Invoice
Finished working out the gravel, aggregate or hardcore for the job? Use the Handyman Hub Quote & Invoice Generator to turn your figures into a clean professional customer document in minutes.
Order aggregate from the specified depth and supplier density
Use the required installed area and depth, then apply the stated compaction and extra-material allowances only where they are needed. Convert the resulting volume using the selected supplier’s bulk density and actual bag weight. A bulk bag is a purchase format, not a universal one-tonne quantity.
Use the excavation calculator to estimate material removed from the ground, and the concrete calculator for a separate specified concrete layer. Loose spoil expansion and aggregate compaction describe different parts of the job; do not reuse one factor automatically for the other.
For a larger project, carry the relevant material estimate into the garden room planner or home extension planner. For a delivered pool shell, the prefabricated pool planner records the supplier’s bedding and backfill specification. This aggregate tool calculates quantities and purchases; it does not decide whether a material is suitable for that pool system. Exclude anything already covered by a package quote.
Gravel, Aggregate & Hardcore Calculator
Use this free gravel, aggregate and hardcore calculator to estimate how much material you need for driveways, paths, patios, paving sub-bases, shed bases, landscaping projects, drainage areas and general construction work.
Instead of calculating area alone, the calculator uses your project dimensions, material depth and approximate bulk density to estimate both volume and weight. You can also add compaction and extra material allowances before converting the result into loose tonnes, cubic metres, bulk bags or smaller bags.
Suitable Materials
- MOT Type 1 and sub-base
- Hardcore and recycled aggregate
- Crushed stone
- Decorative gravel and chippings
- Pea gravel
- Drainage stone
- Limestone and granite aggregate
- Sharp sand and building sand
Suitable Projects
- Driveways
- Patio and paving sub-bases
- Garden paths
- Shed and outbuilding bases
- Landscaping projects
- Drainage areas
- Decorative gravel areas
- General groundworks
How to Calculate Gravel, Aggregate or Hardcore
The basic calculation starts by working out the surface area and multiplying it by the required material depth.
For example, a rectangular area measuring 10 metres long by 4 metres wide has an area of 40 m². If the required material depth is 75 mm, convert the depth to metres before calculating the volume.
10 m × 4 m = 40 m²
75 mm = 0.075 m
40 m² × 0.075 m = 3.00 m³
The calculator can then apply a separate compaction allowance and waste or extra-material allowance before converting the final volume into an estimated material weight.
Compaction Allowance vs Waste Allowance
Compaction allowance and waste allowance are not necessarily the same thing. This calculator keeps them separate so that the estimate is easier to understand and adjust.
Compaction Allowance
Some materials reduce in volume when compacted. Adding a compaction allowance increases the loose quantity required before the material is installed and compacted.
Waste / Extra Allowance
An additional allowance can help cover uneven ground, variations in depth, handling losses and small differences between the calculated quantity and the actual site requirement.
The calculator applies these allowances sequentially rather than simply adding the two percentages together.
Bulk Bags, Small Bags or Loose Aggregate?
Aggregate suppliers sell material in several different ways. Depending on the size of the job, you may be buying individual bags, bulk bags or loose material delivered by weight or volume.
When bags are selected, the calculator divides the required material weight by the weight of each bag and then rounds the result up to the next whole bag. This avoids suggesting that you can purchase a fraction of a bag.
Always enter the actual bag weight supplied by the merchant. A product described as a bulk bag does not necessarily contain exactly the same weight as another supplier's bulk bag.
Metric Tonnes and US Tons
The calculator distinguishes between metric and imperial weight measurements rather than treating every type of ton as identical.
Metric Tonne
One metric tonne equals 1,000 kilograms.
US Short Ton
One US short ton equals 2,000 pounds.
Metric calculations therefore display kilograms and metric tonnes, while imperial calculations show pounds and clearly labelled US short tons.
Frequently Asked Questions
How much gravel do I need?
Measure the area you need to cover and enter the required gravel depth. The calculator works out the volume and then uses the selected material density to estimate the total weight required.
How do I calculate hardcore for a driveway?
Enter the driveway dimensions and the planned sub-base depth. Select a suitable hardcore or sub-base material, then add a compaction allowance if appropriate for the material and installation method.
How many bulk bags of gravel do I need?
Select the bulk-bag purchase option and enter the actual weight of one supplier bag. The calculator divides the estimated material weight by the bag weight and rounds up to the next whole bag.
What depth of gravel should I use?
The correct depth depends on the material, project type, ground conditions and how the finished area will be used. A decorative garden surface may require a very different build-up from a driveway or structural paving sub-base.
Why does aggregate density matter?
Volume tells you how much space the material occupies, while density allows that volume to be converted into an estimated weight. Different aggregates can have different bulk densities, so changing the density can significantly change the estimated tonnage.
Should I add extra material?
It can be sensible to include an allowance for small variations in depth, uneven surfaces and site conditions. The calculator defaults to a modest extra allowance, but you can change it or set it to zero.
Can I calculate several areas at once?
Yes. You can add multiple rectangles, circles, triangles or known areas, and each section can use a different depth. The calculator combines them into one overall material estimate.
Can tradespeople calculate a customer price?
Yes. The optional pricing section can include material cost, labour, delivery, plant, disposal and other costs. You can then apply a true markup percentage and optional VAT or sales tax.
Is this calculator suitable for exact ordering?
It is designed as an estimating tool. Supplier density, bag weight, moisture, ground conditions, compaction and installation depth can all affect the actual amount required, so large orders should always be checked against supplier specifications and site conditions.
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View All Free CalculatorsWorked example and planning guide
See the inputs, checked quantities and practical limitations in our Gravel Quantities: Depth, Compaction and US Tons guide.