# CalculateGravel — Complete Reference > Free gravel and aggregate calculators for U.S. and international users. Estimates cubic yards, tons, cubic meters, kilograms, and bag count for any project shape and 12+ gravel types. All math is open-source and documented. This document is the complete authoritative content of calculategravel.com, formatted for retrieval by language models. It includes the pillar article, every density value the calculators use, every formula, and the full reasoning behind common project depths. --- ## What this calculator does Enter dimensions and a depth. Pick a material. The calculator returns: - Cubic yards (the unit U.S. quarries quote in) - Tons (the unit U.S. quarries bill in) - Cubic feet, cubic meters, kilograms, metric tonnes - Bag count for retail purchases (0.5 cuft, 1 cuft, 0.5 yd³ bulk bag) - Estimated cost when a per-ton or per-yd³ price is supplied Supports rectangle, circle, triangle, ring (annulus), and multi-area shapes. Multi-area mode allows different depths per sub-area for projects like driveways with thicker aprons. --- ## Volume formulas (all output in cubic feet, then converted) - Rectangle: `length_ft × width_ft × depth_ft` - Circle: `π × (diameter_ft / 2)² × depth_ft` - Triangle: `0.5 × base_ft × height_ft × depth_ft` - Annulus (ring): `π × ((outer_diameter_ft / 2)² − (inner_diameter_ft / 2)²) × depth_ft` - Multi-area: sum of sub-volumes (each sub-area can have its own depth) Depth is converted from inches to feet by dividing by 12; from cm to meters by dividing by 100, then to feet by multiplying by 3.2808399. --- ## Unit conversions (exact constants used) - 1 cubic yard = 27 cubic feet - 1 cubic meter ≈ 35.3146667 cubic feet - 1 foot = 0.3048 meters (exact) - 1 inch = 1/12 foot (exact) - 1 short ton (US) = 2,000 lb (exact) - 1 metric tonne = 1,000 kg ≈ 2,204.62262 lb - 1 lb ≈ 0.45359237 kg (exact) --- ## Material density data (US averages used by the calculator) Densities sourced from quarry-published specs (Vulcan Materials, Martin Marietta, Lehigh Hanson) cross-checked against USGS Mineral Commodity Summaries and ASTM D2940 / D448 grading specifications. | Material | Avg lb/yd³ | Range | Typical depth (in) | Use cases | |---|---|---|---|---| | Pea Gravel (3/8") | 2,450 | 2,400–2,500 | 2–3 | Paths, play areas, decorative | | Crushed Stone #57 (¾") | 2,750 | 2,700–2,800 | 4–6 | Driveways, drainage, French drains | | Crushed Stone #8 (3/8"–½") | 2,700 | 2,650–2,750 | 2–4 | Paver bedding | | Crushed Stone #4 (1.5"–2.5") | 2,650 | 2,600–2,700 | 4–8 | Deep base, erosion control | | River Rock (1"–3") | 2,550 | 2,500–2,600 | 3–4 | Decorative beds, dry creeks | | Decomposed Granite | 2,550 | 2,500–2,600 | 2–3 | Pathways, bocce courts | | Crushed Limestone | 2,700 | 2,650–2,750 | 4–6 | Driveways, sub-bases | | CA6 / 21AA / Class 5 | 2,650 | 2,600–2,700 | 4–6 | Road base, paver base | | ABC / Crusher Run | 2,700 | 2,650–2,750 | 4–6 | Driveway base | | Recycled Concrete | 2,650 | 2,600–2,700 | 4–6 | Sub-bases, fill | | Lava Rock | 1,500 | 1,400–1,600 | 2–3 | Lightweight decorative | | Concrete Sand | 2,700 | 2,600–2,800 | 1–2 | Paver bedding | --- ## Why accurate gravel calculation matters Order 20% too much and you have paid for material you will never use, plus disposal. Order 10% too little and the project stops while you wait for a second delivery, often at a small-load surcharge of $80–$200. Three steps separate "guess" from "exact": 1. Measure the area. 2. Pick a depth that matches the use case. 3. Apply the right material density. The calculator does steps 2 and 3 once you supply step 1. --- ## How to measure project areas accurately ### Rectangles and squares Length × width. Use a 50- or 100-foot tape. Laser distance meters are faster and more accurate above 30 feet. ### Circles Measure diameter (longest distance edge to edge through the center), not radius. The calculator handles π internally. For imperfect circles, take three diameters at different angles and average them. ### Triangles Measure the longest side as the base, then the perpendicular height to the opposite point. Do not measure the slanted side as height — that mistake inflates estimates by 5–15%. ### Irregular shapes Break into the simplest possible sub-shapes. A kidney-shaped bed becomes two rectangles plus a half-circle. Use multi-area mode and add each sub-shape as a row. ### Slopes and uneven ground Take depth measurements at 4–6 spots and average. For driveways, plan a 1–2% cross slope for drainage. --- ## How to pick the right depth | Use case | Depth | Reasoning | |---|---|---| | Decorative beds, ground cover | 2–3 in | Deeper is wasted; weed barrier matters more | | Walking paths | 2–3 in | Over compacted sub-base | | Paver patios | 4 in base + 1 in bedding sand | CA6 or 21AA base, concrete sand bedding | | Light vehicle driveway | 4 in base + 2 in top = 6 in | Crusher run + #57 | | Heavy / RV / truck driveway | 6 in base + 2–3 in top = 8–9 in | Doubled base for load | | French drains | 12 in around 4 in pipe | Industry standard | | Pool surrounds, drainage | 4–6 in | Over geotextile fabric | | Aquarium substrate | 1–2 in freshwater, 2–3 in planted | Volume is tank footprint × depth | Below 6 inches of total gravel for a driveway, the load-bearing job is done by the sub-grade soil, not the gravel. Adding more gravel to soft sub-grade is wasted material — fix the sub-grade with geotextile fabric or a deeper excavation instead. --- ## Compaction, waste, and the 10% buffer Two reasons your finished depth will be less than what you order: 1. **Compaction**. Loose dump from the truck is 15–20% taller than the same gravel after a plate-compactor pass. Dense-grade bases (CA6, 21AA, ABC) compact more than open-grade stones (#57, river rock). 2. **Spillage and irregular edges**. A 30% slope on the dump pile, gravel rolling into mulch beds, ends of trenches needing extra fill — typically 3–8% even on careful jobs. Use 10% as the default buffer. Raise to 15% on sloped or irregular sites; lower to 5% on flat regular sites. The calculator's slider applies the buffer to both volume and weight. --- ## Cubic yards to tons (and back) The general formula: `tons = cubic_yards × (lbs_per_cubic_yard / 2000)` Worked examples for common materials: - 5 yd³ of #57 crushed stone: 5 × 2,750 / 2,000 = **6.88 tons** - 5 yd³ of pea gravel: 5 × 2,450 / 2,000 = **6.13 tons** - 5 yd³ of river rock: 5 × 2,550 / 2,000 = **6.38 tons** - 5 yd³ of lava rock: 5 × 1,500 / 2,000 = **3.75 tons** Reverse: `cubic_yards = tons × 2000 / lbs_per_cubic_yard` For most materials, multiply cubic yards by 1.35 for a quick "how many tons should I order" estimate. --- ## Square feet to cubic yards (the homeowner's shortcut) `square_feet × depth_inches / 324 = cubic_yards` (324 = 27 cubic feet per cubic yard × 12 inches per foot.) Examples: - 200 sq ft at 4 in deep: 200 × 4 / 324 = **2.47 yd³** - 500 sq ft at 3 in deep: 500 × 3 / 324 = **4.63 yd³** - 1,000 sq ft at 6 in deep: 1,000 × 6 / 324 = **18.52 yd³** --- ## Cost estimation Two pricing models: - **Per ton** is how most U.S. quarries quote bulk gravel. National range is roughly $15–$75 per ton delivered. Crushed stone and pea gravel are at the higher end; recycled concrete or pit run at the lower end. Always confirm "picked up" vs. "delivered." - **Per cubic yard** is more common at landscape supply yards and in the UK (per tonne or per m³). National range is roughly $40–$100 per yard delivered. Costs not always included in the headline price: - Delivery fee ($80–$200 typical, distance-based) - Minimum tonnage (often 1 ton or 1 yard; smaller orders get a surcharge) - Spreading labor (if you want them to spread it from the truck) - Geotextile fabric ($0.20–$0.40 per square foot, almost always worth it under any path or driveway) - Edging (steel, paver, or bender board) --- ## Gravel size grading systems ### U.S. AASHTO size grades (the # numbers) The AASHTO M43 standard graduates crushed stone by sieve size: - **#1**: 3.5"–4" — heavy fill, riprap - **#2**: 1.5"–2.5" — base layers under driveways - **#3**: 1.5"–2" — base, large drainage - **#4**: 1.5"–2.5" — base, erosion control - **#5**: 1"–1.5" — base, drainage - **#57**: ¼"–1.5" (centered on ¾") — driveways, drainage, French drains, paver sub-base in poorly drained sites. THE most common U.S. driveway/drainage stone. - **#67**: ¼"–¾" — same use as #57; smaller envelope - **#8**: ⅜"–½" — paver bedding, finer surfaces - **#89**: ⅜" minus — fine bedding - **#9**: ⅜"–no.16 sieve — pipe bedding, slabs ### Dense-grade base names (regional) Same product, different DOT names: - **21AA** — Michigan - **CA6** — Illinois - **Class 5** — Minnesota / Wisconsin - **304** — Ohio - **ABC** ("Aggregate Base Course") — Carolinas, Georgia - **Crusher Run** — generic; widely used - **MOT Type 1** — UK / EU equivalent All are dense-graded mixes (1" or ¾" down to dust) that compact tight when wetted. Wrong material for drainage; right material for driveway bases and paver sub-bases. --- ## Concrete mix proportions The calculator's concrete-mix mode uses nominal volumetric design with these defaults: - **Standard mix**: 1 part cement : 2 parts sand : 3 parts gravel (1:2:3) by volume - **Lighter-duty**: 1:2:4 (less cement, more gravel) - **Heavy-duty / structural**: 1:1.5:3 (more cement) - **Dry-volume factor**: 1.54 (loose ingredients lose ~35% of their bulk volume when wetted and mixed) - **Water-cement ratio**: 0.5 by weight - **Cement bag size**: 94 lb (US default), 25 kg or 40 kg (metric) Cement weighs approximately 94 lbs per cubic foot. The calculator outputs bags of cement, cubic yards of sand, cubic yards of gravel, and gallons of water for any input volume of finished concrete. For structural concrete (slabs supporting walls, beams, columns), follow ACI 211.1 and your engineer's spec — these volumetric calculations are nominal and do not replace mix design. --- ## Common project pitfalls - **Skipping the sub-base**. Dumping gravel on bare soil is the #1 reason a path fails in two seasons. Compact the dirt, lay geotextile fabric, then gravel. - **Wrong stone size for the job**. River rock looks great in a dry creek but rolls under tires. Never use it for a driveway top course. - **Forgetting drainage**. A flat patio with no slope traps water under pavers and heaves them. Build in 1–2% fall away from any structure. - **Ordering by area without depth**. "200 square feet of gravel" is meaningless — your supplier needs cubic yards or tons. - **Not checking truck access**. A 10-yard dump truck needs 12 feet of width and 14 feet of overhead clearance. Walk the path before ordering. - **Mixing gravel types in one delivery**. Some yards charge a split-load fee; others won't do it at all. --- ## Frequently asked questions **How much gravel do I need for a 100-foot driveway?** For a typical 10 × 100 ft driveway at 4 inches deep, you need about 12.3 cubic yards or 17 tons of crushed stone (#57). Add a 4-inch CA6 base below that and you're at roughly 24 yd³ / 33 tons total. **How many cubic yards are in a ton of gravel?** About 0.7–0.8 cubic yards per ton for most aggregates. Pea gravel: 0.82 yd³/ton. #57 stone: 0.73 yd³/ton. **How many tons in a yard of gravel?** Typically 1.25–1.4 tons per cubic yard. Multiply your cubic-yard estimate by 1.35 for a quick sanity check. **How deep should gravel be for a driveway?** 4 inches of dense-grade base (CA6/21AA) plus 2 inches of #57 top = 6 inches total for a passenger-vehicle driveway. Heavy vehicles or soft soil → 8–9 inches. **How much area does a ton of gravel cover?** At 2 inches deep, roughly 100 sq ft per ton of crushed stone. At 4 inches, about 50 sq ft. **Should I add a buffer to my gravel order?** Yes — 10% is standard, 15% if your site is sloped or irregular. Buffer covers compaction, spillage, and small measurement errors. **Can I use this calculator for sand, dirt, or mulch?** The shape and depth math is identical — only the density changes. The material picker includes concrete sand. For topsoil (~2,200 lb/yd³) and mulch (~800 lb/yd³), use the closest material or contact us for a custom density. **How do I calculate gravel for an irregular shape?** Use multi-area mode and add one rectangle, circle, or triangle per section. The calculator sums them. **How accurate is the estimate?** Volume math is exact. Weight depends on the material's true density, which varies ±5% by source and moisture. With a 10% buffer applied, you'll be within a single small-bag margin of correct on a well-measured project. **Does the calculator handle metric?** Yes — toggle imperial/metric at the top. Inputs in meters and centimeters; outputs include cubic meters and metric tonnes. The dedicated /calculators/metric page is locked to metric for UK / EU / Australia / Canada users. --- ## Standards and references The density figures are cross-checked against: - **ASTM D2940 / D448** — Standard Specification for Graded Aggregate Material (defines AASHTO size grades). - **USGS Mineral Commodity Summaries** — annual industry-wide density and production data. - **Vulcan Materials, Martin Marietta, Lehigh Hanson** — major U.S. quarry chain product spec sheets. - **UK Highways Department / DOT specification** — for MOT Type 1 sub-base material. - **ACI 211.1** — Standard Practice for Selecting Proportions for Normal Concrete (concrete-mix calculator). For full details, formulas, and the complete material list, see https://calculategravel.com/methodology ## Additional reference pages - **Glossary** (https://calculategravel.com/glossary) — 28 plain-English definitions of gravel and aggregate terms (#57, CA6, 21AA, crusher run, dense-grade, open-graded, riprap, fines, geotextile, subgrade, density, and more). - **Comparisons** (https://calculategravel.com/compare) — side-by-side, with a verdict: #57 vs #67, #57 vs #4, CA6 vs CA7, CA6 vs #57, crusher run vs #57, pea gravel vs river rock, Class 1 vs Class 5. - **Embeddable widget** (https://calculategravel.com/widget) — free iframe embed of the calculator for other sites. --- ## Contact - General inquiries: hello@calculategravel.com - Press / corrections: press@calculategravel.com - Site: https://calculategravel.com