Material referenceMaterial guide

Gravel: sizes, uses and how to plan quantities

Gravel is a broad word covering crushed stone of many sizes and gradations, and the differences are not cosmetic: a stone that makes a good driveway base is a poor decorative cover, and the reverse. This page explains what changes between products, how to plan a quantity, and what to ask for at the counter.

What gravel actually is

Gravel is stone that has been crushed and screened to a target size range. What makes one product different from another is mostly gradation: whether the particles are all roughly one size, or whether a range of sizes is deliberately included. Rock type matters too, because limestone, granite and trap rock behave slightly differently, but gradation is the variable that changes what a product can be used for.

The two ends of the gradation range, and what each is good for
Gradation	What it looks like	What it is used for
Single-size (open graded)	Particles of a similar size, with visible gaps between them	Decorative cover, drainage layers, pipe bedding. Water moves through it
Blended with fines (dense graded)	A mix of stone sizes plus fine material that fills the gaps	Base layers and surfaces that get compacted. It knits together and carries load
Rounded (as opposed to crushed)	Smooth, naturally weathered particles such as pea gravel	Decorative cover, walkways, play areas. It shifts underfoot and does not lock together

Ask for the product by the supplier catalogue name plus the size. Generic words like “gravel” or “drainage stone” mean different things in different regions.

Gradation is a planning decision, not a detail

Using a single-size decorative stone as a base under pavers, or a dense compactable stone as a decorative bed cover, is a common and expensive mismatch. The quantity can be right and the material still be wrong for the job.

Common uses and the size question

Most projects fall into one of a handful of patterns. Identifying which one you are doing tells you whether you need an open-graded stone, a compactable one, or both.

Typical uses and the planning depth each one suggests
Use	Typical gradation	Planning depth	Notes
Garden walkway surface	Open graded or rounded	2–4 in	Usually over a compacted base; edging keeps it in place
Gravel patio seating area	Open graded or rounded	2–4 in	Loose stone is hard on furniture legs
Driveway base	Dense graded with fines	4 in and up, compacted	The layer that spreads load; site-specific
Driveway surface	Dense graded, smaller top size	2 in, compacted	Renewed more often than the base
Drainage layer or French drain	Open graded, single size	Set by the drain detail	Water must move through it; fines defeat the purpose
Pipe and utility bedding	Open graded, single size	Set by the detail	Placed to a specified profile, not raked flat
Decorative bed cover	Single size or rounded	2–4 in	Larger stone needs more depth to hide the fabric below

Gravel (crushed stone): the planning depth ranges behind the calculator's presets
Use case	Planning range	Default	Note
Walkway / path	2–4 in	3 in	Usually laid over a compacted base.
Gravel patio surface	2–4 in	3 in	Surface layer only; base is calculated separately.
General fill	1–6 in	3 in	Adjust depth to your project.

Planning ranges, not site-specific specifications. Your soil, drainage and use can justify a different depth.

Planning a quantity

Gravel quantity is area × depth, converted into whatever unit your supplier sells in. The conversion chain is always the same: cubic feet, then cubic yards, then tons, then bags. What changes between projects is the depth and whether a compaction allowance applies.

Coverage by depth, calculated with the engine's coverage function
Depth	One cubic yard covers	One 0.5 cu ft bag covers
1 in	324 sq ft	6 sq ft
2 in	162 sq ft	3 sq ft
3 in	108 sq ft	2 sq ft
4 in	81 sq ft	1.5 sq ft

Depth is the lever here: at 2 in a bag covers roughly twice the area it covers at 4 in, which is why the depth decision matters more than the stone choice.

Gravel (crushed stone): planning assumptions used by the calculator
Assumption	Planning value
Typical density	1.4 tons/cu yd
Density range seen in practice	1.2–1.7 tons/cu yd
Bag sizes used for bag estimates	0.5 cu ft
Default waste allowance	10%
Order rounding	Nearest 0.25 cu yd

Crushed stone varies by rock type and size; limestone, granite and trap rock differ.

Recalculated by the calculator engine as this page is built

Gravel for a 4 ft × 25 ft garden path

A 100 sq ft path with a 3 in surface layer of gravel, using the walkway preset, the default 10% waste allowance and no compaction allowance because the layer is a loose cover.

Inputs

Material: Gravel (crushed stone)
Area: 4 ft × 25 ft
Depth: 3 in
Waste: 10%

Project area: 100 sq ft9.29 m²
Depth used: 3 in
Volume before waste: 25 cu ft0.93 cu yd
Waste allowance: 10%
Volume to order: 27.5 cu ft1.02 cu yd · 0.78 m³
Order quantity: 1.25 cu ydRounded up to the nearest 0.25 cu yd
Estimated weight: 1.43 tons1.29 tonnes at the 1.4 tons/cu yd planning density
0.5 cu ft bags: 55 bags
Bags or bulk?: Bags or bulk delivery are both reasonable

Same area at different depths (engine output, 10% waste)
Depth	Volume to order	Order quantity	Estimated weight	Smallest bag size
2 in	0.68 cu yd	0.75 cu yd	0.95 tons	37 bags
3 in	1.02 cu yd	1.25 cu yd	1.43 tons	55 bags
4 in	1.36 cu yd	1.5 cu yd	1.9 tons	74 bags

Every column comes from the same calculation engine used by the calculator.

This is the classic small-project result: a volume that bags can still cover, and a comparison table that shows how quickly the order grows with depth. The interesting decision is not the arithmetic but the base beneath — a loose 3 in cover over soft ground will not stay flat regardless of how accurate the quantity is.

Bulk versus bags

Bagged stone is convenient and expensive per unit. Bulk stone is cheaper per unit but arrives in a pile that has to be moved, and it comes with a delivery charge and often a minimum order. The crossover point is roughly where moving bags stops being a five-minute job.

Under about half a cubic yard, bags usually make sense: two people can carry the whole order in one trip.
Between half and two cubic yards, either can work. The deciding factor is usually access rather than price.
Above two cubic yards, a delivered load is almost always easier, provided the truck can place it where you need it.
If access is difficult, a smaller number of larger loads can still beat many small deliveries: ask about the vehicle size before ordering.

Purchasing considerations

What to confirm before ordering

The product by catalogue name and size, not by the word “gravel”
Whether it is open graded or blended with fines, because that decides whether it compacts
The unit the price is quoted in — cubic yard, ton or bag — and any delivery charge
The density figure the supplier uses, if you are ordering by weight
Where the load can be placed, and whether the vehicle can reach it
Whether the stone is washed or contains dust, because that affects how it looks and how it settles
Colour consistency across the batch, if the stone is decorative and visible

One practical point about ordering by weight: because moisture changes the weight of the same volume, a tonnage order and a volume order are not interchangeable. If your supplier sells by the ton, ask what density they price with, and compare that against the cubic yard figure the calculator gives you.

Common mistakes

Mistakes that show up after delivery
Mistake	Consequence	Avoid it by
Ordering decorative stone for a base	The base never locks together and the surface moves	Asking whether the product is blended with fines
Ignoring compaction on a compactable layer	The finished depth falls short	Turning on the compaction allowance and compacting in lifts
Using a dense stone around drainage	Water cannot move through the layer	Specifying an open-graded single-size stone for drainage
Measuring the finished surface for the quantity	The order is short, because the layer below is wider	Measuring at the level the stone will sit on
Assuming all gravel looks the same	A colour or texture that does not match the sample once spread	Ordering a small sample first, or viewing the actual stock

Related guides

Keep going

How much gravel do I need?The measurement and conversion process step by step
How to plan a gravel drivewayMulti-layer planning for vehicle traffic
What changes the price of gravel
Pea gravelThe rounded, smaller cousin, and where it behaves differently
Paver baseThe compactable aggregate used under pavers
Open the Gravel Calculator

Try it: Gravel Calculator

Calculate gravel volume, tons, bags, waste and cost. Every number on this page came from the same engine, so you can replace the example figures with your own measurements and compare.

Frequently asked questions

How many square feet does a ton of gravel cover?

It depends on depth and density. At roughly 1.4 tons per cubic yard, one ton is about 0.71 cubic yards, which covers around 77 sq ft at 3 in deep and around 115 sq ft at 2 in. The calculator works in cubic yards and tons at the same time so you can convert a supplier quote either way.

What size gravel should I use for a walkway?

A surface layer for walking is normally a smaller stone because it is comfortable underfoot, and it is often rounded or a small open-graded product. Larger stone is harder on shoes and furniture legs, and it needs more depth to look finished. The walkway range in the calculator is 2–4 in deep, and the size itself is a supplier catalogue choice.

Does gravel need a base underneath?

For a path that stays flat, yes in most cases: a compactable layer under a decorative cover is what stops the surface migrating and settling unevenly. A thin cover spread straight onto firm, well-drained ground can work, but it will follow whatever the ground does. The calculator plans each layer separately so you can price both.

Is gravel cheaper by the ton or by the cubic yard?

Neither is inherently cheaper; the units describe the same material differently. Convert both to the same figure before comparing. Roughly 1.4 tons per cubic yard is a useful planning factor, and the calculator shows both so a volume quote and a weight quote can be compared directly.

Method and limitations

Where this estimate stops being useful

This material guide describes planning characteristics, not specification requirements. It cannot tell you which gradation your drainage or base actually needs, how deep a layer should be for your soil and loads, or whether a particular product is suitable for a slope, a driveway or a drainage detail. Rock type, gradation, moisture and supplier practice all vary by region. Confirm product suitability with your supplier and, where the work is structural or drainage-related, with a qualified professional.

The methodology page documents how volume, waste, compaction and purchase quantities are produced, and the about page explains what this platform does and does not do.