Gravel Calculator — Tons, Yards, Bags, Coverage & Cost

How much gravel do I need?

Three numbers decide it: the area, the finished depth and the density of the material you are actually buying. The first two are geometry and are not controversial. The third is a measurement of a specific product, and it is where nearly every wrong gravel order begins — which is why this page names the density it used, says whether it was measured loose or compacted, and links the document it came from.

The worked example above is the page's default state, computed by the same engine as everything else: 120 ft² at 2 in finished depth is 20 ft³ (0.7407 yd³), and at 95.4 lb/ft³ that is 0.954 US tons — 0.865 t. Those last two figures are the same gravel. They are different numbers because a US short ton and a metric tonne are different masses, which is the single most common ambiguity in an aggregate order.

Gravel calculator formula

Every output on this page traces to one of the equations below. Nothing else is used.

Geometry — the area

The density identity

The whole calculator turns on one derived quantity, the finished density — the mass per unit of in-place volume:

Volume, weight, coverage and depth

Because the forward and both reverse equations use the same ρ_finished, the reverse solvers reconstruct the forward result exactly — a round-trip test asserts it to within 1 part in 10¹².

In US units the volume chain collapses to a single constant: cubic yards = ft² × depth in inches ÷ 324, because a cubic yard is 27 ft³ and an inch is 1/12 ft, and 27 × 12 = 324. That constant is derived from the exact unit factors in the engine, not typed in.

Gravel density table

Every figure below is transcribed from a named public-agency document, with the table it came from and the date it was retrieved. Where no citable document states a value, the cell says so instead of guessing.

Source policy. A density is published on the page only when it can be traced to a named document with a publisher, a title, a URL and a retrieval date. Where no such document states a value, the field is null and the material is marked not-independently-verified rather than filled with a plausible number. No value in this file comes from a competitor calculator, a supplier marketing page, an SEO article or a generative model.

How much area does one ton of gravel cover?

Coverage is weight ÷ density ÷ depth. It therefore changes with the material, which is why this table is generated from whichever material the calculator has selected rather than printed once and left to rot.

Notice the last two columns. A cubic yard spread one inch deep covers 324 ft² whether it is limestone or granite, because volume coverage involves no density at all. If your supplier sells by volume, that is one less unknown in the order.

Recommended gravel depth

This page does not publish a table of recommended depths, and the honest reason is worth stating plainly: for anything carrying traffic, depth is a pavement-design output — it follows from the strength of the subgrade, the drainage and the axle loads the surface will see. The one public-agency source cited here sizes base thickness through a design procedure rather than by publishing a number, and its only quantitative statement about base course is a compaction target, not a depth.

No universal 'recommended gravel depth' table is published here. Depth for a trafficked surface is a pavement-design output that depends on subgrade strength, drainage and traffic loading; the one public-agency source cited above sizes it from a design procedure rather than publishing a fixed number. Any depth this page offers as a preset is a starting point you can and should change, and it is labelled as such.

Whatever depth you choose, four things change the answer and none of them is in this calculator: the soil beneath, how well the ground drains, the traffic and loading the surface will carry, and your local construction requirements. Where a job is structural, the depth belongs to whoever is responsible for the design.

Why gravel density is not one fixed number

A calculator that applies a single factor — the folklore figure is "1.4 US short tons per cubic yard" — is quietly asserting that all gravel weighs the same. The measured data says otherwise, and the reasons are physical. (Even that folklore figure is quoted without saying which ton it means, which is the second problem with it.)

Bulk density is not particle density

The density of the rock and the density of a pile of that rock are different quantities. Solid granite is published at 159–180 lb/ft³; loose crushed stone in the table above measures 85.7–115.8 lb/ft³. The difference is air. A loose aggregate is roughly a third to a half voids, and it is the voids, not the mineralogy, that dominate the number you need.

Gradation and voids

An open-graded material is deliberately single-sized so water can move through it, which leaves large voids. A well-graded material has small particles filling the gaps between large ones, so more mass fits in the same box. The FHWA data shows this directly: the No. 10 sample — the finest and most broadly graded of the set — measured 115.8 lb/ft³ loose against 92.3 lb/ft³ for the No. 78, and the report notes it "was the heaviest, weighing as much as a conventional well-graded aggregate, but it also has the highest coefficient of uniformity".

Angular versus rounded

Crushed material has angular faces that interlock and bridge, holding voids open; rounded river material packs more readily. This is also why a compaction factor measured on crushed stone does not transfer to pea gravel, and why this page will not offer one preset factor for both.

Moisture

Every laboratory figure quoted here is oven-dry. Real aggregate off a yard in February is not. Water adds mass without adding much volume, so a wet load weighs more per cubic yard than the dry figure predicts. The National Park Service guidance on stone weight makes the same point from the other direction, advising that 10%–20% be added for stone if it has rained recently.

Loose versus compacted state

The same aggregate, measured two ways, gives two right answers. In the sourced table above the loose-to-densified ratio ranges from about 1.03 for the No. 56 sample to about 1.26 for the No. 10 — a spread far too wide for a single universal compaction assumption. That is why every density on this page carries a state label, and why "state not stated" lowers the estimate-quality rating rather than being quietly treated as one or the other.

Supplier-specific measurement

All of the above is why the most reliable number available to you is not on this page at all: it is the unit weight your supplier measures for the product on their yard. This calculator's custom-density field exists to take that figure, and the receipt records that it came from you.

ASTM C29/C29M is the standard test method for bulk density and voids in aggregate, and it is cited here for methodology only. It is worth knowing what it is: the standard specifies how the measure is filled — by rodding, jigging or shovelling — precisely because the answer depends on the procedure. A material does not have one bulk density; it has a bulk density under a stated method. No numeric value on this page is attributed to that standard, because it publishes none.

Tons vs cubic yards vs bags

These are three different kinds of quantity and converting between them requires exactly one thing — a density — except in the one case where it does not.

• Weight (tons, tonnes, pounds, kilograms). The most reliable trade unit, because it is measured on a weighbridge. It is also the most ambiguous word: a US short ton is 2,000 lb (907.18 kg), a metric tonne is 1,000 kg, and a UK long ton is 2,240 lb (1,016.05 kg). A quote of "10 tons" spans a 12% band — about a full tonne on a ten-tonne order. Every weight on this page names which one it is.
• Volume (cubic yards, cubic metres). Needs no density to convert to coverage, but does depend on state: what arrives on the truck is the loose volume, and it will occupy less once compacted in place. This calculator prices bulk volume on the loose figure for that reason.
• Bags. A discrete purchase. 52.5 bag-equivalents means 53 bags, and the half-bag left over is shown as its own line so it is never confused with the ordering overage you chose.

Worked through: 20 ft³ of material at 95.4 lb/ft³ is 1908 lb. That is 0.954 US tons, 0.865 t, or 0.852 long tons — three different numbers for one pile of gravel.

Gravel cost calculator

The cost panel in the calculator above compares as many suppliers as you enter, on whatever basis each of them quotes: price per US ton, per metric tonne, per cubic yard, per cubic metre or per bag, with delivery, other fees, tax, minimum orders and supplier increments handled per option.

No price is stored anywhere on this page, and none is suggested. Gravel prices vary by product, quarry, haul distance, region and season by more than any national average could usefully describe, so this tool compares your figures and names the lowest of the options you entered. It does not tell you what gravel costs.

Two details matter when you compare a weight quote against a volume quote. First, the volume that gets priced is the loose volume — that is what the truck delivers, and using the finished volume would under-order by exactly the compaction factor. Second, supplier rounding is applied last: if a yard sells in quarter US short tons, an order of 1.05 US short tons becomes 1.25, and you pay for 1.25. This page shows the calculated quantity, the overage, the order quantity and the supplier-rounded quantity as four separate numbers, so you can see exactly where the money went.

Driveway gravel calculator

A gravel driveway is almost never one material. It is a subbase, a base and a surface course, each with its own gradation, its own density, its own compaction behaviour and often its own supplier — which is why "how much gravel for a driveway" has no single answer and why the layered mode in the calculator above exists.

Each layer is an independent calculation. It carries its own material and density with its own state and source, its own finished depth, its own compaction factor and its own ordering overage, and the layers are summed at full precision into one delivery schedule. Nothing is rounded per layer before the total, because rounding each layer first is how estimates drift upward.

Worked through on a 40 ft × 12 ft drive (480 ft²) with the three default layers, the schedule totals 23.7 US tons — 17.78 yd³ of loose material across 3 layers. Change any layer's material, depth or compaction and only that layer moves.

What the calculator will not do is tell you how deep to build it. That is a design decision about your subgrade, your drainage and your traffic, and the driveway and parking presets deliberately leave the depth field empty rather than imply otherwise.

Worked examples

All three are produced by the engine at build time and are protected by a regression test — if the engine changes, these numbers change with it or the build fails.

1. A landscape rectangle

120 ft² at 2 in of Crushed stone, AASHTO No. 57 (diabase) (95.4 lb/ft³, loose, from FHWA-HRT-15-034).

• Finished volume: 20 ft³ = 0.7407 yd³
• Weight required: 0.954 US tons = 0.865 t = 1908 lb
• Ordering overage applied: 0% — the default, so the order equals the requirement
• In 50 lb bags: 39 whole bags (38.16 exact)

2. A layered driveway material requirement

A 40 ft × 12 ft drive built as subbase, base and surface course:

• Subbase — Crushed stone, AASHTO No. 5 (diabase) at 6 in: 11.39 US tons (8.89 yd³ loose)
• Base — Crushed stone, AASHTO No. 67 (diabase) at 4 in: 8.5 US tons (5.93 yd³ loose)
• Surface gravel — Crushed stone, AASHTO No. 57 (diabase) at 2 in: 3.82 US tons (2.96 yd³ loose)
• Total delivered: 23.7 US tons = 21.5 t

3. Reverse: coverage from a known weight

You have already been delivered 5 US tons and want it at 3 in finished depth.

• Finished volume it represents: 3.882 yd³ (104.8 ft³)
• Area it will cover: 419 ft² = 39 m²
• Check: that area × that depth × the same finished density returns the 5 US tons you started with — which is what the round-trip test asserts.

Accuracy and assumptions

What this calculator assumes

• Gravel is assumed to be spread at a uniform finished depth across the area you entered; real ground varies.
• Every dimension is normalized to metres, kilograms and kg/m³ before any arithmetic runs, and the display unit never changes the physical result.
• A density measured loose is converted to a finished (in-place) density by multiplying by the compaction factor exactly once. A density already measured compacted is not scaled again.
• No compaction is assumed unless you choose a factor. The default is 1.00, and the page says so rather than hiding a factor inside the total.
• No settling, waste or ordering allowance is added unless you deliberately choose one; the default overage is 0%.
• Whole bags and whole supplier increments are rounded up: you cannot buy 0.4 of a bag, and a yard that sells in quarter tons will not deliver 1.37.
• Bulk material priced by volume is priced on the LOOSE volume, because that is what arrives on the truck.
• Prices, delivery fees, taxes, supplier increments and minimum orders are the figures you supply. None is stored, assumed or averaged.
• The word 'ton' is never used alone. A US short ton (2,000 lb), a metric tonne (1,000 kg) and a UK long ton (2,240 lb) differ by more than 12% and are always named.

What it cannot do

• The published densities on this page are laboratory index values for specific, single-source, open-graded aggregates from named quarries in Virginia and Ohio. They are a sourced planning anchor, not a national average and not a substitute for your supplier's own figure for the product you are buying.
• Laboratory minimum and maximum index densities (ASTM D4254 and D4253) are not the same measurement as ASTM C29 bulk density, and neither is the same as a field in-place density under a roller.
• No bulk density is published here for pea gravel, river rock, decorative gravel, decomposed granite, crushed granite or sand-and-gravel mix, because no citable document was found that states one. Those materials require a density you supply.
• No loose, as-delivered density is published for dense-graded road base: the cited source states only an in-place compacted target.
• Moisture changes bulk density and is not modelled. Wet aggregate weighs more per unit volume than the dry laboratory figures shown here.
• Compaction factors are a property of a material, its moisture content and the compaction method. This page asks for yours rather than supplying one, and offers no preset factor at all.
• Uneven ground, ruts, slopes and soft spots absorb more material than a flat rectangle of the same measured area.
• There is no universally correct gravel depth. For anything carrying traffic, depth is a pavement-design output that depends on the subgrade, the drainage and the axle loads — not a number a calculator can supply.
• An area measured from a plan or an aerial image carries the uncertainty of that source; it is an estimate, not a survey.
• This is a planning estimate. Confirm densities, bag sizes, increments, minimum orders and delivery terms with your supplier before ordering.

Methodology & sources

Calculator version

gravel-calculator engine 1.0.0 · workspace 1.0.0

Density dataset version

gravel-material-densities 1.0.0 (20 materials, 14 with published densities)

Last updated

August 17, 2026

Author

Ugo Candido

External review status

No independent third-party technical review of this calculator has taken place. The author is responsible for the methodology; correctness is enforced by the engine's golden reference vectors, the forward/reverse round-trip suites, the unit-equivalence and physical-invariant suites, the fail-closed dataset validator proved against deliberately invalid fixtures, and the dedicated renderer suite. The density data is not CalcDomain's own measurement: every published figure is attributed to a named public-agency document with its URL, its retrieval date and the table it was read from, and any figure that could not be sourced that way is shown as an empty cell rather than estimated.

Source policy

A density is published on the page only when it can be traced to a named document with a publisher, a title, a URL and a retrieval date. Where no such document states a value, the field is null and the material is marked not-independently-verified rather than filled with a plausible number. No value in this file comes from a competitor calculator, a supplier marketing page, an SEO article or a generative model.

Unit policy

Every input is parsed once into canonical SI (metres, square metres, cubic metres, kilograms, kg/m³) before any arithmetic runs. Cubic and density factors are derived from the exact linear and mass factors, never typed twice. A display unit is never the input of another conversion. The word "ton" is never used without saying which ton.

Rounding policy

Intermediate values are never rounded. Rounding happens only for display and at the two genuinely discrete steps — whole bags and the supplier order — each with a 1e-9 relative tolerance so an exact multiple never gains a spurious extra unit. Bags round up, never down.

Source hierarchy

1. 1. Test-method standards (what a density measurement means) — cited for methodology only, never for numeric values.
2. 2. Federal and state public-agency publications (FHWA, USDA NRCS, NPS, state DOTs) — the numeric backbone of this dataset.
3. 3. Technical data sheets from named producers — none currently used.
4. 4. Authoritative aggregate producer associations — none currently used.
5. 5. Verifiable engineering references — none currently used.

Every source cited on this page

1. ASTM International — ASTM C29/C29M, Standard Test Method for Bulk Density ("Unit Weight") and Voids in Aggregate (ASTM C29/C29M), published 2023, retrieved 2026-08-17. Hierarchy tier 1.
   METHODOLOGY ONLY. C29/C29M defines how bulk density ("unit weight") and voids in aggregate are measured — by filling a measure of known volume in a specified way (rodding, jigging or shovelling) and weighing it. It is the reason a single aggregate legitimately has more than one correct density: the standard specifies the filling procedure because the answer depends on it.
   Scope and limits: This standard publishes a TEST METHOD, not density values. No number anywhere in this dataset is attributed to ASTM C29/C29M, and none should be.
2. ASTM International — ASTM D4253 (maximum index density, vibratory table) and ASTM D4254 (minimum index density, funnel) (ASTM D4253 / ASTM D4254), published 2016, retrieved 2026-08-17. Hierarchy tier 1.
   METHODOLOGY ONLY. These are the two test methods FHWA-HRT-15-034 used to produce the loose and densified unit weights transcribed in this dataset: D4254 Method A pours the dry aggregate through a funnel (loosest repeatable state), D4253 Method 1A vibrates it on a table under a surcharge (densest repeatable state).
   Scope and limits: These standards publish test methods, not density values. They are cited here to explain what the FHWA loose and compacted columns physically mean.
3. Federal Highway Administration, U.S. Department of Transportation — Strength Characterization of Open-Graded Aggregates for Structural Backfills (FHWA-HRT-15-034), published 2015-06, retrieved 2026-08-17. Hierarchy tier 2.
   Chapter 3, table 7 ("Unit weight of aggregates"). The report states: "The minimum and maximum dry unit weight for the aggregates were determined using the funnel (Method A of ASTM D4254) and vibratory table (Method 1A of ASTM D4253) methods, respectively." The minimum index dry unit weight is therefore a LOOSE, poured, dry state and the maximum index dry unit weight is a DENSIFIED, vibrated, dry state. Sample identity, rock type and quarry location come from table 5 ("OGAs tested"). Gradations were verified by sieve analysis against AASHTO M43.
   Scope and limits: These are laboratory index densities on oven-dried, single-source, OPEN-GRADED aggregates from specific Virginia and Ohio quarries. They are not a national average, not a dense-graded road base, and not the same measurement as ASTM C29 bulk density or a field in-place density. Use them as a sourced planning anchor, not as a substitute for your supplier's own figure.
4. USDA Natural Resources Conservation Service — Earth and Aggregate Surfacing Design Guide, Agricultural Engineering Technical Note No. AEN-4 (TN 210-AEN-04), published 2017-08, retrieved 2026-08-17. Hierarchy tier 2.
   Aggregate base course section. The guide states: "The base course should be compacted to a CBR of 80 or to about 125 to 135 pcf." This is an IN-PLACE COMPACTED target for a well-graded aggregate base course, expressed as a range, not a loose as-delivered density.
   Scope and limits: A compaction target for a designed base course under traffic, achieved with a roller. It is not the density of the same material loose on a truck, and a decorative or open-graded gravel will not reach it.
5. U.S. National Park Service — Calculating the Weight of Stone, published 2025-04-07, retrieved 2026-08-17. Hierarchy tier 2.
   Published density ranges for SOLID stone in lb/ft³, used with the article's own formula "ft3 x lbs/ft3 = lbs". The article also notes that 10%–20% should be added for stone if it has rained recently.
   Scope and limits: These are SOLID-ROCK (particle) densities for dimension stone. They are deliberately NOT used as gravel bulk densities anywhere in this calculator: loose gravel is stone plus the air between the stones, so its bulk density is far lower. They appear on the page only to show the reader the size of that gap.
6. California Department of Transportation — California Test 212, Method of Test for Unit Weight of Aggregate (CT 212), published 2010-05, retrieved 2026-08-17. Hierarchy tier 2.
   METHODOLOGY ONLY. A state DOT test method covering the determination of the COMPACTED or LOOSE weight per cubic foot of fine and coarse aggregate — independent confirmation from a public agency that loose and compacted unit weight are two distinct measured quantities for the same material.
   Scope and limits: Publishes a test method, not density values. No number in this dataset is attributed to CT 212.

Materials deliberately left unverified

• Pea gravel (rounded) — No standards body, public agency or producer technical data sheet was found publishing a bulk density for pea gravel that could be cited with a document title, URL and date. The figures circulating on landscaping and calculator sites trace back to each other rather than to a measurement, so nothing is published here. Ask your supplier for the unit weight of the product you are buying and enter it as a custom density — the calculator then works normally and the receipt records where the number came from.
• River rock (rounded, washed) — River rock is a size-and-appearance description, not a specification: the same product name covers several rock types with genuinely different densities, and no citable document publishes a bulk density for it. Enter your supplier's figure as a custom density.
• Decorative gravel / landscape stone — "Decorative gravel" is a retail category covering everything from light volcanic rock to dense granite. There is no single material to measure, so there is no honest single density to publish. Use your supplier's figure as a custom density.
• Decomposed granite — Decomposed granite varies with the degree of weathering, the fines content and whether a stabiliser is blended in; no citable document publishes a bulk density covering the range sold as DG. Enter your supplier's figure as a custom density.
• Granite gravel / crushed granite — The National Park Service publishes a SOLID granite density of 159–180 lb/ft³, but that is the rock itself with no voids; it is not the bulk density of granite gravel and must not be used as one. No citable bulk density for crushed granite was found. Enter your supplier's figure as a custom density.
• Sand and gravel mix — Bank-run and pit-run sand-and-gravel is whatever the pit yields; the sand fraction alone moves the density substantially and is not controlled. No citable bulk density was found for it. Enter your supplier's figure as a custom density.

How this calculator is tested

The quantity chain is pinned by golden reference vectors (120 ft² at 2 in and 105 lb/ft³ = 20 ft³ = 1.05 US short tons = 53 bags of 40 lb), the reverse solvers by forward/reverse round-trip tests, and the physics by invariant suites: quantity grows with area, depth and density; coverage shrinks as depth grows; bags never round down; overage never reduces a quantity; and the unit a reader types never changes the physical result. The density dataset has its own fail-closed validator, proved against twenty deliberately invalid fixtures — a record missing a source, a unit, a state, a retrieval date, or with min above max, is rejected rather than rendered.

Frequently asked questions

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