Gravel Calculators
Gravel types and sizes explained
"#57", "crusher run", "¾-inch minus", "Class 5" — gravel names look like a secret code because, mostly, they are one: descriptions of the sieve sizes a stone passes through. Here's how to read them, and which grade fits which job. Every code below is pre-loaded into our Gravel Calculators with correct densities, so you can estimate any of them directly. All of these are also built into the material selector of every calculator on this site.
Sources and method: the formulas and density figures used here are the site's standard values, documented on the methodology page together with the hand-calculated test cases.
The two big families
Gravel in the strict sense is naturally rounded stone — river and stream rock, tumbled smooth. It's comfortable, decorative, and drains well, but round particles roll instead of locking, so it never compacts into a hard surface. Crushed stone is mechanically broken quarry rock: angular, with fractured faces that interlock. Add fine material ("fines" or "dust") and it compacts almost like pavement. Rule of thumb: round for looks, crushed for structure.
Sources and method: the formulas and density figures used here are the site's standard values, documented on the methodology page together with the hand-calculated test cases.
Round vs angular, head to head
Because shape drives performance, the choice between natural gravel and crushed stone decides most projects before size even enters the conversation:
| Property | Gravel (round) | Crushed stone (angular) |
|---|---|---|
| Compacts? | No — pieces roll past each other | Yes — faces interlock (especially with fines) |
| Drainage | Good; water flows between stones | Good washed; slow with fines |
| Underfoot | Comfortable, loose | Firm, locks into a surface |
| Under tires | Ruts and scatters | Holds a shape |
| Look | Soft, natural, decorative | Industrial, textured |
| Stays put? | Needs edging — migrates | Self-constraining |
Shape also affects cost: crushed stone is usually cheaper per ton (quarries make it in bulk), while pea gravel is commonly bagged — so the "expensive" one often depends on how you buy it.
Sources and method: the formulas and density figures used here are the site's standard values, documented on the methodology page together with the hand-calculated test cases.
Numbered grades: reading the code
ASTM-style stone numbers describe the sieve range a gradation passes. Lower numbers are bigger stone. The same numbering idea repeats worldwide under different names — Europe's "single-sized aggregates", the UK's MOT/Type 1 (a fine, compacting base mix), and state DOT specs in the US (e.g. "Class 5" base in Minnesota, "Item 4" in New York, Caltrans Class 2). Regional names differ; the physics doesn't: angular-and-fined compacts, round-and-washed drains and decorates.
| Code / name | Typical size | Metric | Typical use |
|---|---|---|---|
| #1 / "#2 stone" | 2–4" | 50–100 mm | Deep sub-base over soft ground; erosion control |
| #4 | 1½–2½" | 37–63 mm | Base layers, drainage fills, gabions |
| #5 | 1–1½" | 25–37 mm | Drainage, road base ingredient |
| #57 | ¾" washed | ~19 mm | The all-rounder: driveway tops, French drains, septic, concrete mix |
| #67 | ¾" minus | ≤19 mm | Driveways, paths, pipe bedding, slab base |
| #8 / pea gravel | ⅜–½" | 9–13 mm | Walkways, playgrounds, decorative beds |
| #9 / #10 ("screenings") | like sand–⅜" | ≤9 mm | Paver bedding, top-dressing, ice traction |
| Crusher run / crush and run | ¾" with fines | ≤19 mm + dust | Compacting bases: driveways, roads, pads |
| MOT Type 1 (UK) | to 1½" with fines | ≤40 mm + fines | UK standard compacting sub-base |
| Class 5 / Item 4 (US state specs) | to ¾–1" with fines | ≤19–25 mm + fines | State-spec compacting road/patio base |
Sizes are nominal — actual gradations vary by quarry and region, and state specs change. For a purchase decision, your supplier's sieve sheet wins over any table, including this one.
Sources and method: the formulas and density figures used here are the site's standard values, documented on the methodology page together with the hand-calculated test cases.
Matching the grade to the job
- Driveway base: crusher run / dense-graded base (or your state's equivalent), 4–6" compacted. Quantities: driveway calculator.
- Driveway surface: #57 or #67, 2–3" over the base.
- French drain: washed #57 or #4 — the wash matters, fines clog the flow.
- Under pavers: crusher-run-style base 4–6" + screenings or sand bedding. Paver base calculator.
- Walkways & play areas: pea gravel (#8), 2–4" — comfortable, but use solid edging to keep it in place.
- Concrete aggregate: #57 is the classic gravel component of residential mixes.
- Blends and concrete quantities: split cement, sand, and gravel with the concrete mix ratio calculator or the sand and gravel mix calculator.
Shape, size, and weight — how they connect
Density is why the same volume weighs differently across materials: clean washed stone has air between angular particles (≈ 95–105 lb/ft³), while fines-filled crusher run packs dense (≈ 115–120 lb/ft³), and pea gravel sits between (≈ 105–110 lb/ft³). In tons per cubic yard: roughly 1.35 for washed stone, up to ~1.6 for dense-graded base — a 15% swing on the same order. Every calculator on this site states the exact density it used, and the tons calculator shows the full conversion table.
Sources and method: the formulas and density figures used here are the site's standard values, documented on the methodology page together with the hand-calculated test cases.
Tools for the grades above
- Gravel calculator — includes #1, #4, #57, #67, crusher run, pea gravel, and sand in the material selector
- Crushed gravel calculator — pre-set for crushed stone and dense-graded base
- Pea gravel calculator — depths and bag math for #8 / pea stone
Last updated: September 20, 2026
This guide is part of browse every gravel guide on this site.