Gravel Calculator

The arithmetic under the pile

cu yd = length ft × width ft × (depth in ÷ 12) ÷ 27. The worked path: 300 sq ft × 0.25 ft (a quarter of a foot) = 75 cu ft = 2.78 cu yd. A 5% cushion lifts it to 2.92 cu yd, ordered as 3 whole yards with 0.08 cu yd spare. At a supplier-quoted 1.4 tons per cu yd that load weighs about 4.08 tons — a figure the tool prints only because the example supplies a density, exactly as the form does. These figures come from the engine at build time, not from copy-editing.

The units underneath that chain — why a cubic yard holds exactly 27 cubic feet, how cubic meters relate to both, and how a footprint and a depth become a volume — are the subject of the guide Cubic feet, cubic yards, and ordering concrete. It is written around concrete, but the volume arithmetic is identical for a bed of stone; the differences are the rounding unit at the end — a whole cubic yard here, the smaller increment ready-mix is ordered in there — and the optional tonnage line, which no concrete tool has. Read it if the conversions are new to you. The rest of this page explains what this calculator does with the numbers you give it, stage by stage, and how to read what comes back.

What the calculator computes, stage by stage

Every estimator on this site follows the five-stage pipeline documented on the methodology page. The gravel tool runs all five, adds one optional conversion of its own, and — because bulk stone is sold by volume rather than by the bag — has a coverage stage with no package yield in it, which it shares with the sand and topsoil tools.

1. Geometry. Length times width gives the footprint in square feet. The depth is divided by 12 to turn inches into feet, and the footprint times that decimal depth is the net volume in cubic feet; dividing by 27 gives net cubic yards. Nothing is rounded here: the engine carries the full-precision figures forward and only the digits on screen are trimmed. In metric mode the meters and centimeters you type are converted to feet and inches first — meters ÷ 0.3048, centimeters ÷ 2.54, both exact definitions — so the arithmetic downstream is identical in both systems.
2. Coverage. On most tools this stage divides by a published yield: how much one bag, box, or bundle covers. Bulk aggregate has no package, so there is no yield to divide by and the stage is a pass-through here: the cubic-yard conversion already happened in the geometry stage, and no manufacturer figure enters this page at all. The site's materials data deliberately holds no gravel density either — it is a user input, for reasons the tonnage section below explains.
3. Waste. The engine applies net × (1 + cushion ÷ 100) to the cubic-feet volume, then converts the result to cubic yards. The default of 5% is a trade convention recorded in the site's materials data for aggregate and mulch, where depth variation is the main overrun; it is not a manufacturer figure, and the form lets you replace it, including with zero. The result is the adjusted volume: what the job is expected to consume.
4. Package rounding. The "package" here is one cubic yard, the unit bulk aggregate is typically sold in, so the engine computes ceil(adjusted cu yd) — the adjusted volume rounded up to the next whole yard. This is the only rounding in the chain and it always rounds up. The spare is the order minus the adjusted volume: stone beyond the cushion that the rounding obliges you to buy. When the division lands on a whole number within floating-point noise, the engine treats it as an exact fit rather than adding a phantom yard. Because the increment is a full yard — the same unit the sand and topsoil tools round to, and a coarser one than the bag counts or the 0.25 cu yd ready-mix increment the other estimators on the site round to — this step can move the order by a whole yard at a time, which is why the examples below show the adjusted figure and the order side by side.
5. User-priced cost. If you type a price per cubic yard, the cost is that price times the ordered quantity — the rounded figure, not the adjusted one, because the rounded figure is what you buy by the yard. The site never supplies or averages a price; leave the field blank and the line does not appear.

The tonnage line sits outside the five stages. When you enter a density, the engine multiplies the stage-three figure — the adjusted cubic yards — by it: tons = adjusted cu yd × tons per cu yd. It is a conversion of the volume you expect to place, not of the whole-yard order, and it appears only when the density field holds a number. The engine never defaults that field.

Why each input matters

Length and width set the footprint, and the volume scales with each of them directly: doubling either doubles the adjusted volume, though the whole-yard order moves in steps. Both go in as decimal feet. The form has no separate inches box, so a tape reading of 45 ft 6 in is entered as 45.5 — the inches divided by 12 and added to the whole feet, which is the convention every material estimator on this site follows before any arithmetic runs. (The trade-geometry tools — the feet & inches, stair, roof pitch, and board foot calculators — work in sixteenths of an inch instead; the methodology page covers both conventions.) The feet & inches calculator shows the decimal-feet equivalent of an awkward reading. If the bed is not one rectangle, settle the total square footage first with the square footage calculator and enter it as the length with a width of 1.

Depth is the input to watch. It is small, it is entered in inches while the other two fields take feet, and it comes from your project or your contractor's specification rather than from this calculator: how deep a layer should be depends on what it is for, and that is a judgment the tool deliberately does not make. Arithmetically it is a straight multiplier — the volume moves in exact proportion to it — which is why the unit slip described below is so costly. If the stone will arrive as separate deliveries, run the tool once per delivery, because the whole-yard rounding applies to each order separately.

The cushion multiplies the volume, so it moves the adjusted figure proportionally and the order in whole-yard steps. Small changes often change nothing, because the round-up absorbs them; then a further change tips the order by a full yard. It is a single flat percentage: there is no separate allowance for an uneven subgrade, for stone lost at the edges, or for settlement — whatever you want covered is folded into this one number, and the examples below show the default, zero, and a raised figure.

Supplier density is optional and touches only the tonnage line. Leave it blank and the result stops at cubic yards, complete and correct; enter the figure your quarry or landscape yard quotes and a tons line appears. The field takes US short tons per cubic yard, must be greater than zero, and is capped at 10 tons per cubic yard — a sanity ceiling held in the engine to catch a figure typed in the wrong unit, not a property of any material.

Price per cubic yard touches only the last line. It never feeds back into the quantity, so you can add or change it after the fact without disturbing the order.

The units toggle changes what the fields expect and how the result is presented, not what is computed. In metric mode, meters are divided by 0.3048 and centimeters by 2.54 — both exact definitions — before the engine sees them, and the result panel leads with cubic meters while still reporting the whole-yard order, labelled as US yards.

The figures this page relies on

• Default cushion, 5% — a common trade convention recorded in the site's materials data, where it is labelled a convention because no primary source publishes a universal waste figure; it is the modest allowance for bulk aggregate and mulch, where depth variation is the main overrun. Adjustable in the form.
• Density — none. The materials data holds no gravel density on purpose, because crushed stone, pea gravel, river rock, and recycled concrete weigh differently and moisture shifts the figure further. It is a user input, and the tonnage line exists only when you supply it.
• Density ceiling, 10 tons per cubic yard — a sanity limit held in the gravel engine. It is not a material figure and says nothing about what stone weighs; it rejects entries that can only be a unit mistake, such as a pounds figure typed into the tons field.
• Ordering increment, one whole cubic yard — the engine's rounding unit, following the cubic yard bulk aggregate is typically sold by. A convention rather than a rule: a yard that sells smaller scoops changes only the last step, and the unrounded adjusted figure is on the result to order from.
• Inches per foot, 12, and cubic feet per cubic yard, 27 — definitions, exact.
• Meters per foot, 0.3048, and centimeters per inch, 2.54 — exact definitions, used only to convert metric entries into the engine's feet and inches. Cubic meters per cubic foot, 0.028316846592, and square meters per square foot, 0.09290304, present the volume and footprint back in metric; both are the international foot cubed and squared.
• Pounds per US short ton, 2,000 — a definition held in the site's unit converter. The engine does not use it; it matters only if your supplier quotes pounds per cubic yard and you need to divide before entering tons.

Worked examples

Every figure in this table was produced at build time by the same engine that runs the form above. The inputs are chosen to show different behaviours of the pipeline: a small bed where the whole-yard rounding dominates, a large one where the cushion does, an exact fit, a priced order, and a metric entry converted exactly before the engine ran, which is what the metric toggle does. The depths are example inputs, not recommendations.

The driveway. 50 × 12 ft at 4 in is 600 sq ft; at 4 ÷ 12 = 0.3333 ft deep that is 200 cu ft, 7.41 cu yd net, or 5.66 m³. The 5% cushion lifts it to 7.78 cu yd and the order is 8 cu yd with 0.22 cu yd of rounding. On a large bed the adjusted volume rarely sits far below a yard boundary, so the spare is a small share and the cushion, not the rounding, governs the order. This is the bed the tonnage section below weighs at two different quoted densities.

The patio base. A 12 × 14 ft footprint at 6 in — half a foot — is 168 sq ft and 84 cu ft, 3.11 cu yd net. With the cushion the adjusted volume is 3.27 cu yd, and because it has crossed a yard boundary by a fraction the order is 4 cu yd with 0.73 cu yd spare: a large share of the order is rounding. The pavers that will sit on top of this base are counted by the paver calculator, which also sizes the bedding sand.

The garden path, with and without a cushion. 40 × 3 ft at 2 in is 120 sq ft and only 20 cu ft — 0.74 cu yd net. The default cushion makes that 0.78 cu yd, ordered as 1 cu yd with 0.22 cu yd spare. Set the cushion to 0 and the same path still orders 1 cu yd, 0.26 cu yd more than it holds, because the whole-yard round-up does not go away when the allowance does. Below a yard the rounding is the whole story, and the unrounded figure is the one to quote to a yard that sells by the scoop.

The walkway measured in feet and inches. The tape says 45 ft 6 in by 4 ft, so the length is entered as 45.5 ft. At 3 in the 182 sq ft walk is 45.5 cu ft, 1.69 cu yd net; the cushion takes it to 1.77 cu yd and the order is 2 cu yd with 0.23 cu yd spare. The inches were converted before the engine ran — the decimal-feet convention the material estimators follow (the trade-geometry tools work in sixteenths; see the methodology page).

The exact fit. 36 × 6 ft at 6 in is 216 sq ft and 108 cu ft — exactly 4 cu yd net. With the cushion raised to 25% — a figure chosen to land on a whole yard — the adjusted volume is exactly 5 cu yd, and the order is 5 cu yd with 0 cu yd spare. Binary arithmetic can leave a product like this a hair above the boundary; the engine's exact-fit tolerance is what keeps it from adding a phantom yard. This page's build checks that the spare is zero and fails if it is not.

The priced order. 20 × 20 ft at 4 in is 133.33 cu ft net, 5.19 cu yd after the 5% cushion, and an order of 6 cu yd. With $10.00 per cubic yard (an arbitrary figure, not a market price) typed into the price field, the cost line reads $60.00 — the ordered quantity times the price, nothing else. That price is a placeholder chosen only to show the arithmetic; the site holds no gravel prices, and the cost is computed on the rounded order because the rounded order is what you buy by the yard.

The metric bed. In metric mode, 9 × 3 m at 8 cm reaches the engine as 29.53 × 9.84 ft at 3.15 in. The footprint is 27 m² (290.63 sq ft) and the net volume 2.16 m³ — 76.28 cu ft, 2.83 cu yd. With 5% the adjusted volume is 2.27 m³ (2.97 cu yd), and the whole-yard convention rounds it to 3 cu yd, shown as 2.29 m³. The result panel leads in cubic meters, but the order underneath it is the same one the imperial path would produce from the converted dimensions.

Yards are measured; tons are quoted

Volume is geometry — it cannot be wrong if the tape measure was right. Weight belongs to the material: the same yard of rock can vary by hundreds of pounds between products and moisture states. That is why this page never embeds a density. When a supplier quotes “about 1.4 tons to the yard”, type that in and the conversion is theirs, not ours.

The mechanism is one multiplication, and where it sits in the chain matters. Take the driveway above: 7.41 cu yd net, 7.78 cu yd adjusted, 8 cu yd ordered. Type a density of 1 ton per cubic yard — a stand-in, not a figure for any product — and the tons line reads 7.78: the adjusted yards exactly, because the engine multiplies the stage-three figure, not the order. Type 2 and it reads 15.56, double, while every cubic-yard line is unchanged. The volume is yours and fixed; the weight belongs to whatever the density field holds. If your supplier sells by weight, the tons line is the figure to give them and the whole-yard rounding is irrelevant to the order; if they sell by the yard, the order line is the figure and the tons line is information.

The field has one guard. It takes US short tons per cubic yard, so a supplier who quotes in pounds per cubic yard has given you a number in the thousands: the hint example's 1.4 tons is 2,800 lb. Type that pounds figure as it stands and the engine refuses it — “Enter a density of at most 10 tons per cubic yard.” — rather than printing a weight thousands of times too high. Divide by 2,000, the pounds in a short ton by definition, enter 1.4, and the line returns at 4.08 tons. The ceiling of 10 tons per cubic yard exists for exactly this slip; it is not a statement about what any stone weighs.

How to read the result

The headline line is the purchase decision: Order N cu yd. Beneath it, Net … layer shows the footprint and the bare geometry in cubic feet and cubic yards, so a typo in a dimension is visible before it is padded; With N% extra shows the waste-adjusted volume with the percentage that produced it; and Rounded to whole yards repeats the order with the spare in parentheses — the stone the rounding added beyond the cushion. Read the net line to check your geometry, the adjusted line to check your allowance, and the order line to place a by-the-yard order. A tons line appears only when a density is entered and a cost line only when a price is; each multiplies a different figure — the adjusted volume and the rounded order respectively — as the tonnage section above explains. In metric mode the same lines lead with cubic meters, converted from the engine's figures with the exact factor above, and the whole-yard line is labelled as the US ordering figure. The copy button places a short plain-text summary of the result on the clipboard.

Common misreadings

Depth in feet. Depth goes in as inches; length and width as feet. Enter the 3 in path as 3 feet deep and the engine sees 36 in: the same 300 sq ft footprint becomes 900 cu ft, 33.33 cu yd net, and an order of 35 cu yd instead of 3 — 12 times the correct net volume, because there are 12 inches to the foot. If the cubic-yard figure looks wildly high, check the depth field first: the misreading is a unit, not a formula, as the methodology page says, and the figures above show what it does to the volume. The guide linked above shows the slip in the other direction too.

Metric figures in the imperial fields. The metric bed above is 9 × 3 m at 8 cm. Type those same numbers with the toggle still on Imperial and the engine sees a 9 × 3 ft bed 8 in deep: 18 cu ft and an order of 1 cu yd, against the correct 3. The error is not a simple factor, because two of the three fields shrank and the third grew; if the order looks implausibly small for the bed, check the toggle.

Cushion as a fraction. The cushion field takes a percentage. The priced order at 5% orders 6 cu yd; typed as 0.05 it is read as 0.05%, the adjusted volume falls to 4.94 cu yd, and the order drops to 5 — 1 cu yd short of the intended allowance, with no warning, because a fraction of a percent is a valid input.

Pounds in the tons field. Covered above: the engine rejects it with a message rather than guessing. The reverse — a weight typed where a volume was wanted — cannot happen here, because the tool never asks for a weight as an input, only a density.

Reading the tons line as the order. The tons line weighs the adjusted volume, not the rounded yards. If you are buying by the yard it will be a little lighter than the whole-yard order would weigh whenever there is spare; that gap is the spare, expressed in tons, and it is not an error. On an exact fit like the one above there is no spare, and the two figures coincide.

Padding twice. Rounding a dimension up before entering it, or adding a margin to the order afterwards, repeats work the pipeline already does: the cushion is applied to the volume and the round-up to the cushion, exactly once each. The garden path above shows what the rounding alone adds; the cushion is meant to be the only other margin.

Where the model stops

The engine models one rectangle of uniform depth and assumes that shape is what gets built. It does not model a subgrade that is not flat, edges that feather out, or a bed that is deeper in one place than another — those are among the reasons real consumption differs from the geometry, and the cushion is the single flat percentage you are given to fold them into. It does not model compaction: how much a loose yard settles once it is placed is a judgment that varies with the material and the use, as the FAQ below says, and the methodology page lists it among the simplifications every estimator shares. It holds no density, so it cannot tell you what a load weighs without your supplier's figure, and it cannot account for moisture beyond whatever that figure already reflects. It sizes the stone and nothing else — quantities only, never engineering: base preparation, drainage, delivery minimums, and anything load-bearing or permit-related are outside the model, as the note under the form says, and need a qualified contractor or engineer. Whole-yard rounding is a convention, not a rule; a yard that sells smaller increments changes only the last step, and the volume underneath it does not move.

The rest of the aggregate pile

The same area × depth → cushion → whole-yard chain runs the sand calculator (screeding and bedding layers) and the topsoil calculator (planting and grading). Gravel going under a paver patio? The paver calculator counts the units and the bedding sand that sit on top of this base. The mulch calculator runs the same volume chain but ends in bags. The square footage calculator settles an irregular footprint, the feet & inches calculator turns tape readings into decimal feet, and the construction unit converter moves any figure between cubic yards and cubic meters, or pounds and tons. For the units and the reasoning behind the chain, see cubic feet, cubic yards, and ordering concrete; for the one input that is a judgment rather than a measurement, waste factors, explained; for the unit toggle, metric and imperial in the estimators; or browse all guides.

Frequently asked questions

Nothing you type leaves your device. See how estimates are constructed and tested on the methodology page, and measure irregular footprints with the square footage calculator first.