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Gravel calculator

Enter the area and the layer depth in metric or US customary units, then the bulk density of the material you are buying. The calculator gives the volume and the weight in metric tonnes and in US short tons, and asks you to say whether your density figure is for loose or compacted material.

Written by Kenneth Schrøder, Founder of WiseCalcs

Updated ·Sources verified

Volume is length × width × depth. Weight is that volume times the bulk density. Because gravel is delivered by weight while you measure in volume, the density is the number that decides the order — and the answer is given in both tonnes and short tons, which are not the same unit.

m
m
cm

Each option fills in a density from WSDOT Design Manual Exhibit 620-1 and says whether that figure is loose or compacted. Typing your own density switches this to Custom.

t/m³

Tonnes per cubic metre. Ask your supplier for the figure for the material you ordered — it changes with the aggregate and with how wet it is.

Loose is what arrives on the truck; compacted is what the finished layer weighs in place. The calculator does not convert between them.

%

Optional margin of your own for spillage, settling and an uneven sub-base. It is your assumption, not a property of the material. Leave it at 0 for the bare measured quantity.

Order weight — metric tonnes

1.13 t

Order weight — US short tons: 1.24 tn

Measured layer
Layer volume
0.75 m³
Layer volume in yd³
0.981 yd³
Order volume
0.75 m³

You said this density is for loose material, so the weight is that much material as delivered. A layer that is then compacted takes up less room than the loose pile did, so measure the finished layer and expect to buy more than its bare volume.

No compaction factor is applied. How much a given aggregate consolidates depends on the material, the moisture and the plant used, and ASTM C29 states that the relationship between compaction in a stockpile and in the laboratory test is unknown. Ask your supplier rather than trusting a single multiplier.

The result updates as you type. The headline is the weight to order in your system's unit, with the other unit directly beneath it. The note underneath says whether the answer describes loose or compacted material, because the calculator never converts between the two.

How does it work?

The metric tonne and the US short ton are genuinely different units, and both figures are computed from the same kilogram result rather than one being the other relabelled. No compaction factor is applied: the volume is the layer you measured and the weight is that volume at the density you entered, so the page asks you to say whether that density is for loose or compacted material and reports the answer in those terms.

Gravel volume and weight

V=l×w×d,m=V×ρ,morder=m(1+s100)V = l \times w \times d,\quad m = V \times \rho,\quad m_{order} = m\left(1 + \tfrac{s}{100}\right)
V
Volume of the layer you measured.
l, w
Length and width — metres, or feet in US mode.
d
Layer depth — centimetres, or inches in US mode. Brought to the same unit as l and w first.
ρ
Bulk density — tonnes per cubic metre, or pounds per cubic yard in US mode.
m
Weight of that layer, reported in metric tonnes (1,000 kg) and in US short tons (2,000 lb = 907.18474 kg).
s
Any extra you choose to order, in percent. Your assumption, shown as its own line.

A 5 m × 3 m area 5 cm deep is 0.75 m³ (0.981 yd³). At 1.5 t/m³ that is 1.13 metric tonnes, which is 1.24 US short tons — the same gravel, two different units. In US mode a 16 ft × 10 ft area 2 in deep is 26.67 ft³ (0.988 yd³); at 2,850 lb/yd³, the WSDOT loose figure for crushed surfacing top course, it weighs 1.41 short tons (1.28 metric tonnes).

Method & sources

Metric mode takes metres, centimetres and tonnes per cubic metre; US customary mode takes feet, inches and pounds per cubic yard. Switching converts the numbers, so the layer stays the same size. The volume is the layer you measured: length × width × depth, treated as an even rectangular layer. Weight is that volume times the bulk density you entered, reported in metric tonnes (1,000 kg) and in US short tons (2,000 lb = 907.18474 kg).

Sources

Where this method comes from — use these references to understand the formula, assumptions, and limits.

How we calculate

  • Metric mode takes metres, centimetres and tonnes per cubic metre; US customary mode takes feet, inches and pounds per cubic yard. Switching converts the numbers, so the layer stays the same size.
  • The volume is the layer you measured: length × width × depth, treated as an even rectangular layer.
  • Weight is that volume times the bulk density you entered, reported in metric tonnes (1,000 kg) and in US short tons (2,000 lb = 907.18474 kg).
  • You declare whether that density describes loose or compacted material. The calculator says which one the answer describes and applies no factor either way.
  • The material presets come from Exhibit 620-1 of the WSDOT Design Manual, which lists each material once as truck measure (loose) and once as compacted on roadway.
  • The extra-to-order percentage is your own assumption, starts at 0, and is shown as a separate line rather than folded into the layer.

Limitations

  • No compaction factor is applied. How far an aggregate consolidates depends on the material, the moisture and the plant, and ASTM C29 states that the relationship between compaction in a stockpile and in the laboratory test is unknown.
  • Bulk density varies with grading and with how wet the material is. The presets are a starting point, not a specification for what your supplier will deliver.
  • The layer is treated as an even rectangle. Split an irregular area into rectangles and add them.

Rounding

Weights are shown to two decimals and volumes to three. The calculation uses full precision throughout.

What this calculator does

Gravel is measured in volume and delivered by weight, so the job is to bridge the two. This calculator multiplies the area by the layer depth to get a volume, converts it into the other volume unit, and multiplies by the bulk density you supply to get a weight. It works in metres, centimetres and tonnes per cubic metre, or in feet, inches and pounds per cubic yard, and switching converts the numbers rather than reinterpreting them.

Every weight appears twice: once in metric tonnes of 1,000 kg and once in US short tons of 2,000 lb. Both come from the same kilogram result, so neither is the other relabelled. They differ by about ten percent, which is easy to overlook on a quote.

How to measure and use it

  1. Pick metric or US customary units.
  2. Measure the area's length and width, then the finished depth of the layer.
  3. Pick a material to fill in a density, or type your supplier's own figure.
  4. Say whether that density is for loose material as delivered, or for compacted material in place.
  5. Add an extra percentage only if you want a margin of your own; it starts at zero and appears as its own line.
  6. Order by whichever unit your supplier quotes in — the page gives tonnes, short tons and both volumes.

A worked example

A 5 m × 3 m area at 5 cm deep is 0.75 m³, or 0.981 yd³. At 1.5 t/m³ that is 1.13 metric tonnes — and 1.24 US short tons. Same gravel, same pile, two different units.

In US mode, a 16 ft × 10 ft area 2 in deep is 26.67 ft³, or 0.988 yd³. At 2,850 lb/yd³ — the WSDOT truck-measure figure for crushed surfacing top course — it weighs 1.41 short tons, which is 1.28 metric tonnes.

Loose or compacted: why the calculator asks

A tonne of gravel takes up more room loose on a lorry than it does compacted in a finished layer, so the same material has two different bulk densities depending on which state you mean. The WSDOT table the presets come from lists both: ballast is 3,100 lb per cubic yard as truck measure and 3,900 lb per cubic yard compacted on the roadway. Using the wrong one is a quarter of the answer.

The calculator will not guess between them. It asks you to declare which state your figure describes and then says so beside the result, but it applies no compaction factor — because there is no single factor to apply. How far a given aggregate consolidates depends on its grading, its moisture and the plant used, and ASTM C29, the standard test for bulk density, states plainly that the relationship between compaction in a stockpile and in the test itself is unknown. If you need to know how much loose material makes a given compacted layer, that is a question for your supplier about their material.

Where to find a density

Ask your supplier first: they know the grading and the moisture of what is actually on the yard. The presets here are a fallback, taken from one public source so you can check them — Exhibit 620-1 of the Washington State Department of Transportation's Design Manual, which tabulates unit dry weights for gravel base and surfacing. Bear in mind those are dry weights; wet material weighs more per cubic metre.

Common mistakes

  • Entering the depth in the wrong unit — metres instead of centimetres, or feet instead of inches.
  • Reading a tonnage as short tons when the supplier quoted metric tonnes, or the reverse. The page names both.
  • Using a loose density against a compacted layer, or the other way round.
  • Taking a density from a different aggregate. Pea gravel and crushed stone do not weigh the same.
  • Treating an irregular area as one rectangle instead of splitting it.

When it's useful

Planning a drive, a path, a shed base or a sub-base under a slab — anywhere you have measured a layer and need to turn it into a delivery.

FAQ

How is the weight calculated?
Volume is length × width × depth, with the depth brought to the same unit as the other two first. Weight is that volume multiplied by the bulk density you entered. The result is then expressed in metric tonnes and in US short tons from the same underlying kilogram figure.
What is the difference between a tonne and a short ton?
A metric tonne is exactly 1,000 kg. A US short ton is 2,000 pounds, which is 907.18474 kg — about ten percent less. A load quoted as 20 tons in the US is not the same as 20 tonnes in Europe, so the page always says which one it means.
Does it account for compaction?
No, deliberately. It reports the layer you measured at the density you entered, and asks you to say whether that density is for loose or compacted material so the answer can be read correctly. There is no universal compaction factor: it depends on the aggregate, the moisture and the equipment, and ASTM C29 notes that the relationship between compaction in a stockpile and in the laboratory test is unknown.
Where do the material presets come from?
Exhibit 620-1 in the WSDOT Design Manual, which gives unit dry weights for gravel base and surfacing separately as truck measure and as compacted on the roadway. Each preset carries its state with it, so choosing one also sets the loose-or-compacted answer. Your supplier's figure beats any table.
What is the extra-to-order percentage for?
Spillage, settling and an uneven sub-base — whatever margin you think the job needs. It starts at zero, it is your assumption rather than a property of the material, and it is shown as a separate line so the measured layer stays visible underneath it.
Tonnes or cubic metres — which do I order in?
Whichever your supplier quotes. The page gives both weights and both volumes so you can match the quote without converting anything by hand.
Can I share a calculation?
Yes. Share copies a link that reopens the calculator with the same area, depth, density and settings, and download saves a plain text file with the inputs, the results and the loose-or-compacted note.

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