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Measure → Calculate → Understand → Plan

Know exactly how much gravel to order.

Calculate how much gravel or aggregate you need — then understand exactly what the result means. GravelMatter turns the measurements of a path, bed, pad or driveway into cubic yards, tons, tonnes and bags, and shows every assumption on the way.

Open the gravel calculatorHow it's calculated

Also: Cubic yards Yards ↔ tons Driveway layers Ordering checklist

  • 8 calculators
  • 6 practical guides
  • 1 shared, tested engine

Try it on the drawing

200 ft²
Estimated order · 10% waste2.04 yd³≈ 2.89 US tons at 105 lb/ft³ · Gravel

§ 01 — Start with the right calculator

Start with the job in front of you.

The gravel calculator handles most jobs. The others answer narrower questions — pure volume, a two-layer driveway, a ton-based quote — and hand their results on to each other.

01Gravel calculatorMeasure each area, set the depth, and get the order quantity in cubic yards, tons and bags. The density is shown, sourced and editable — change it to your supplier's figure.
In
areas · depth · density
Out
yd³ · tons · tonnes · bags · cost
Next
yards ↔ tons · driveway
Open calculator →

§ 02 — The estimation problem

Gravel isn't length × width.

An area is a surface. To order material you need a volume, then the unit your supplier sells in, then a quantity they can actually deliver. Each step is a place where estimates go wrong — so GravelMatter shows every one.

  1. MeasureArea of each shape, in ft² or m². Rectangles, circles, triangles or a known area.L × W · π(d/2)² · ½bh
  2. Set depthThe average thickness of the layer. Depth drives the result more than anything else.in ÷ 12 = ft
  3. Calculate volumeArea × depth gives cubic feet — the raw geometric volume.ft² × ft = ft³
  4. Convert unitsCubic yards for bulk, m³ for metric. Weight only with a density.ft³ ÷ 27 = yd³
  5. Estimate materialAdd compaction (if compacted) and waste as separate lines, then weight and bags.× (1+c) × (1+w)
  6. Plan the orderRound up to the supplier's increments and confirm their units and conversion factor.↑ ½ yd³ · whole bags

§ 03 — Worked through

One chain of arithmetic, every step visible.

A 30 × 4 ft garden path, 3 in deep, worked through exactly as the calculator does it. Each figure is the real output of the engine.

  1. MeasureArealength × width120 ft²
  2. CalculateVolumearea × depth30.0 ft³
  3. Calculate+ Waste× 1.1033.0 ft³
  4. UnderstandWeight× 105 lb/ft³1.73 tons
  5. PlanOrderround up to ½ yd³1.5 yd³

§ 04 — Depth

One inch changes the whole order.

Volume rises in direct proportion to depth: going from 2 in to 3 in adds 50%; from 3 in to 6 in doubles it. On the same 200 ft² area the bulk order runs from 1.5 to 4.5 yd³.

20 × 10 ft (200 ft²) of gravel at 105 lb/ft³ — generated by the GravelMatter engine
DepthVolume+10% wasteBulk order≈ Weight0.5 ft³ bags
2 in1.23 yd³1.36 yd³1.5 yd³1.92 t74
3 in1.85 yd³2.04 yd³2.5 yd³2.89 t110
4 in2.47 yd³2.72 yd³3.0 yd³3.85 t147
6 in3.70 yd³4.07 yd³4.5 yd³5.78 t220
Area covered by one cubic yard (27 ft³ ÷ depth in feet)
Depth1 yd³ coversMetric
1 in324 ft²30.1 m²
2 in162 ft²15.1 m²
3 in108 ft²10.0 m²
4 in81 ft²7.5 m²
5 in65 ft²6.0 m²
6 in54 ft²5.0 m²

Not sure what depth to use? The depth and coverage guide explains what drives the choice and what published guidance exists.

§ 05 — Units

Cubic feet, cubic yards, tons, bags.

Volume units come straight from your measurements. Weight units need a density. Bags need a bag size. Knowing which one your supplier uses avoids the most expensive misunderstandings.

Volume, weight and bags — what each unit means
UnitWhat it measuresWhen it's useful
Cubic feet (ft³)Your raw volume: area in ft² × depth in ft.Checking the arithmetic; bagged products labelled in ft³.
Cubic yards (yd³)27 ft³. The common unit for bulk loose material in the US.Ordering bulk by volume.
Cubic metres (m³)1 yd³ = 0.76 m³.Metric measurements and metric suppliers.
US tons2,000 lb. Needs a density: 1 yd³ of dry gravel at 105 lb/ft³ ≈ 1.42 tons.Suppliers who weigh loads and quote per ton.
Tonnes (t)1,000 kg — about 10% more than a US ton. 1 yd³ at 105 lb/ft³ ≈ 1.29 t.Metric suppliers. Confirm ton vs tonne.
BagsWhole bags of a stated size. 1 yd³ = 54 × 0.5 ft³ bags, or 57 × 50 lb bags at 105 lb/ft³.Small jobs bought from a store.

§ 06 — Material & quantity

Same yard. Different weight.

Volume comes from your measurements. Weight depends on the material — which is why the density is always shown, sourced and editable. See the sources.

  • Gravel1.42 t/yd³
  • Pea gravel1.42 t/yd³
  • Crushed stone1.42 t/yd³
  • River rock1.42 t/yd³
  • Landscape rock1.42 t/yd³
  • Road base1.42 t/yd³

§ 07 — Worked examples

Six real jobs, worked through.

Each example shows the inputs, the arithmetic, the result and what to do with it. Every figure is produced by the same engine the calculators use, and each one opens pre-filled.

Garden walkway

A straight walkway beside a lawn, finished in general gravel.

Inputs
30 × 4 ft · 3 in deep · 10% waste · 105 lb/ft³
Calculation
120.00 ft² × 3/12 ft = 30.00 ft³ (1.11 yd³) × 1.10 waste = 33.00 ft³

1.5 yd³ to order purchase volume 1.22 yd³ · ≈ 1.73 US tons · or 66 × 0.5 ft³ bags

What it means: 1.22 yd³ is what the path needs after a 10% margin; most bulk suppliers deliver in half-yard steps, so 1.5 yd³ is the practical order. At 66 bags, compare the bag price with a small delivery.

Open this example in the calculator →

Pea gravel patio

A square seating area surfaced with pea gravel, small enough that bags are an option.

Inputs
12 × 12 ft · 3 in deep · 10% waste · 105 lb/ft³
Calculation
144.00 ft² × 3/12 ft = 36.00 ft³ (1.33 yd³) × 1.10 waste = 39.60 ft³

1.5 yd³ to order purchase volume 1.47 yd³ · ≈ 2.08 US tons · or 80 × 0.5 ft³ bags

What it means: Bags and bulk are both realistic at this size: 80 small bags or 1.5 yd³ loose. The tons figure uses the general gravel value — pea gravel from your supplier may differ.

Open this example in the calculator →

Shed base

A compacted crushed-stone pad under a garden shed.

Inputs
16 × 12 ft · 4 in deep · 10% waste · 20% compaction · 105 lb/ft³
Calculation
192.00 ft² × 4/12 ft = 64.00 ft³ (2.37 yd³) × 1.20 compaction × 1.10 waste = 84.48 ft³

3.5 yd³ to order purchase volume 3.13 yd³ · ≈ 4.44 US tons

What it means: Because the 4 in is the compacted depth, a 20% compaction allowance is added before waste. Crushed stone is usually sold by weight, so the ≈4.44 tons (with the supplier's factor) is the number to quote.

Open this example in the calculator →

Border and tree ring

A decorative rock border plus a circular bed around a tree.

Inputs
20 × 3 ft + circle Ø 6 ft · 3 in deep · 10% waste · 105 lb/ft³
Calculation
88.27 ft² × 3/12 ft = 22.07 ft³ (0.82 yd³) × 1.10 waste = 24.28 ft³

1.0 yd³ to order purchase volume 0.90 yd³ · ≈ 1.27 US tons

What it means: Two shapes added together. Less than a cubic yard is needed — check whether the supplier has a minimum load before ordering bulk.

Open this example in the calculator →

Dry creek bed

A shallow drainage channel lined with river rock.

Inputs
40 × 3 ft · 4 in deep · 10% waste · 105 lb/ft³
Calculation
120.00 ft² × 4/12 ft = 40.00 ft³ (1.48 yd³) × 1.10 waste = 44.00 ft³

2.0 yd³ to order purchase volume 1.63 yd³ · ≈ 2.31 US tons

What it means: Large rounded rock leaves more air between stones than finer material, so treat the weight as approximate and ask the supplier for their figure for that product.

Open this example in the calculator →

Two-layer driveway

A 60 × 10 ft single-car driveway: a base layer and a surface layer of crushed stone.

Inputs
600 ft² · base 3 in + surface 3 in (compacted) · 20% compaction per layer · 5% waste · 105 lb/ft³
Calculation
each layer: 600 × 3/12 = 150.00 ft³ × 1.20 × 1.05 = 189.00 ft³ = 7.00 yd³

14.0 yd³ in total 7.0 yd³ per layer · ≈ 19.85 US tons

What it means: two separate orders (or one split delivery) — different stone for each layer. The 20% compaction value is a planning allowance; ask the supplier what they see for their product.

Open the driveway calculator →

§ 08 — When estimates differ

Why two honest estimates disagree.

Most differences between calculators — or between you and your supplier — come from three choices. GravelMatter makes each one visible and editable.

1 · Density

Volume is geometry; weight depends on what's in the pile. The published gravel range (91–120 lb/ft³) turns the same 2 yd³ into 2.46–3.24 tons.

Material (reference value)lb/ft³2 yd³ weighs
Dry sand97≈ 2.62 tons
Gravel105≈ 2.84 tons
Wet sand119≈ 3.21 tons
Wet gravel125≈ 3.38 tons

2 · Allowances and rounding

A waste margin and rounding up to a deliverable unit change the order more than people expect — and they interact.

12 × 12 ft at 3 in, gravel
Waste allowancePurchase volumeBulk order≈ Weight
0%1.33 yd³1.5 yd³1.89 t
5%1.40 yd³1.5 yd³1.98 t
10%1.47 yd³1.5 yd³2.08 t
15%1.53 yd³2.0 yd³2.17 t

3 · Loose vs compacted

If you measured the finished, compacted depth, you need more loose stone. These are the allowances that match a given reduction.

Compaction allowance = 1 ÷ (1 − reduction) − 1
Expected volume reductionLoose material to add
10%11%
20%25%
30%43%

§ 09 — From calculation to order

Turn the number into a purchase.

The order sheet is built to be handed to a supplier: print it or copy it. Then confirm these six things.

Read the ordering guide
  1. Pick the material and sizeName and size number (e.g. #57 crushed stone, pea gravel). Ask what the supplier stocks.
  2. Bring your quantity — with its unitFrom the order sheet: the rounded bulk order in yd³ or m³, or tons/tonnes if they sell by weight.
  3. Give the dimensions and depthArea, depth and whether the depth is loose or compacted, so they can sanity-check your number.
  4. Ask for their conversion factorIf they sell by weight, ask their tons per yard (or density) and enter it in the calculator.
  5. Confirm units and incrementsUS ton or metric tonne? Minimum load? Half-yard steps? Bag size?
  6. Ask about delivery and accessWhere the load can be tipped, and any delivery charge — these aren't in our cost line.

§ 10 — Common mistakes

Eight ways an estimate goes wrong.

Each one is easy to make and expensive to discover on delivery day. The numbers are worked examples from the engine.

  1. Depth entered in the wrong unit

    What goes wrong: Typing 3 for a 3-inch layer while the depth unit is set to feet multiplies the volume by 12: a 10 × 10 ft area becomes 11.11 yd³ instead of 0.93 yd³.

    How to avoid it: Check the unit beside the depth field. The calculators warn when a depth is over 24 in.

  2. Dividing cubic feet by 3 or 9

    What goes wrong: 54 ft³ is 2 yd³ (÷ 27), not 6 (÷ 9) or 18 (÷ 3). Yards, square yards and cubic yards are different units.

    How to avoid it: Volume in ft³ always divides by 27. The order sheet shows ft³ and yd³ side by side.

  3. Confusing area with volume

    What goes wrong: 200 ft² is a surface. Without a depth there is no quantity to order.

    How to avoid it: Always pair an area with a depth. Use the cubic yard calculator if you only need volume.

  4. Treating tons and cubic yards as the same thing

    What goes wrong: Weight depends on the material. The same 2 yd³ is about 2.62 tons of dry sand but 3.38 tons of wet gravel at the reference values.

    How to avoid it: Convert with a density you can see — ideally your supplier's — using the yards-to-tons calculator.

  5. Assuming every gravel weighs the same

    What goes wrong: The published gravel range of 91–120 lb/ft³ turns 2 yd³ into anything from 2.46 to 3.24 tons.

    How to avoid it: Ask the supplier for their weight per yard or conversion factor and type it into Density.

  6. Measuring a curved or L-shaped area as one rectangle

    What goes wrong: Using the longest length and widest width counts ground that isn't there and over-orders.

    How to avoid it: Split the area into rectangles, circles and triangles and add each one. See the measuring guide.

  7. Forgetting compaction on compacted layers

    What goes wrong: Stone packs down. A 30% volume reduction needs about 43% more loose material than the geometric volume.

    How to avoid it: If your depth is the finished, compacted depth, set a compaction allowance. Leave it at 0 for loose decorative cover.

  8. Ordering the exact decimal

    What goes wrong: 1.47 yd³ isn't something most suppliers deliver; bags come in whole units.

    How to avoid it: Use the rounded bulk-order line (next ½ unit) or the whole-bag count, and confirm the supplier's increments.

§ 11 — Limits

What the calculators cannot know.

GravelMatter does exact arithmetic on the inputs you give it. These things are outside the calculation, so check them with your supplier or on site.

  • Your supplier's exact materialDensity, size grading and moisture of the actual stone in the pile.
  • Ground conditionsSoft soil, ruts and dips that swallow extra stone.
  • How the material compactsReal settlement depends on the stone, the compaction method and traffic.
  • SlopesAreas are treated as flat plan areas.
  • Delivery constraintsMinimum loads, truck capacity, access and tipping space.
  • Prices and feesWe never publish prices; cost uses the price you enter.
  • Installation qualityUneven spreading changes how far a load goes.
  • Engineering requirementsLoad-bearing or drainage-critical work needs a qualified professional.

§ 12 — Learn

Before you order.

Practical guides for measuring, choosing the stone and depth, and placing the order — plus reference tables for conversions, coverage and densities.

§ 13 — Methodology

Every number shows its working.

The order sheet separates the plain geometric volume from the allowances you choose, then shows the density used to reach tons. Formulas, unit factors and every source are published in full.

Read the methodology
5
published sources, each cited where it's used. Where no product-specific figure exists, we say so.
154
automated arithmetic checks on the shared engine, including every worked example on the site.
0
invented prices. Cost uses the price from your own supplier's quote.

§ 14 — Questions

Quick answers.

Each answer links back to the calculation that produces it. For full detail, see the methodology and references.

How do I work out how much gravel I need?

Measure the area (length × width, or split it into shapes), choose a depth, multiply to get cubic feet, divide by 27 for cubic yards, add a waste margin, then round up to what your supplier sells. The gravel calculator does each step and shows it.

How many square feet does a cubic yard of gravel cover?

It depends on depth: about 162 ft² at 2 in, 108 ft² at 3 in and 81 ft² at 4 in (27 ft³ ÷ depth in feet).

How many tons is a cubic yard of gravel?

About 1.42 US tons at the 105 lb/ft³ reference value for dry gravel. Real products vary — the published gravel range is roughly 1.23–1.62 tons per yd³.

Why is my supplier's number different from mine?

Usually density (their stone weighs more or less than the reference), different rounding or minimum loads, or a different allowance for compaction and waste. Enter their conversion factor and compare like with like.

Should I buy bags or bulk?

Bags suit small areas; one cubic yard is 54 bags of 0.5 ft³. Compare the bag total with a bulk delivery including its delivery charge.

Does GravelMatter work in metric?

Yes. Switch to Metric for metres, centimetres, m³ and tonnes. For example 6 × 3 m at 7.5 cm is 1.35 m³, or 1.48 m³ with 10% waste.