Box / room
Also: rectangular prism, bed, trench, room
V = L × W × H
L = length, W = width, H = height or depth.
Example: A garden path 30 ft long and 3 ft wide, 3 in deep: 30 × 3 × 0.25 = 22.5 cu ft = 0.83 cu yd, about 1.1 tons or 45 bags.
Quick answer: cubic yards of pea gravel = length × width × depth (in feet) ÷ 27. One cubic yard weighs about 1.35 tons and covers about 108 sq ft at 3 in deep. One ton covers about 80 sq ft at 3 in.
How to calculate pea gravel
- Measure the length and width of the area in feet. For curves, pick a shape in the calculator or split the area into pieces and add them to the project total.
- Choose a depth in inches from the guide below and divide by 12 to get feet.
- Multiply length × width × depth to get cubic feet, and divide by 27 for cubic yards.
- Convert to tons if you buy by weight: cubic yards × about 1.35.
- Add 5–10%: pea gravel settles a little and some always ends up outside the edging.
Tons = L × W × D (ft) × 100 lb ÷ 2,000
A garden path 30 ft long and 3 ft wide, 3 in deep.
3 ÷ 12 = 0.25 ft. 30 × 3 × 0.25 = 22.5 cu ft = 0.83 cu yd.
22.5 × 100 lb = 2,250 lb = 1.13 tons, or 45 bags of 50 lb. With 5% extra, order 1 yard or 1.2 tons.
Formulas for paths, patios and drains
Pick the matching shape in the calculator. These are the ones pea gravel jobs use most, each worked through with real numbers.
Area × depth
Also: square feet to cubic feet
V = A × d
A = area, d = depth or thickness.
Example: A 144 sq ft patio (12 × 12 ft) at 4 in deep: 144 × 0.333 = 48 cu ft = 1.78 cu yd, about 2.4 tons.
Cylinder
Also: round hole, post hole, tank, planter
V = π × r² × h
r = radius (half the diameter), h = height.
Example: A round fire-pit area 14 ft across, 3 in deep: π × 7² × 0.25 = 38.5 cu ft = 1.43 cu yd, about 1.9 tons.
Trench / trapezoid
Also: ditch, berm, swale, trapezoidal prism
V = (a + b) ÷ 2 × h × L
a = top width, b = bottom width, h = depth, L = length.
Example: A French drain trench 12 in wide and 24 in deep, 40 ft long (pick equal top and bottom widths for straight sides): 1 × 2 × 40 = 80 cu ft = 2.96 cu yd, before taking out the pipe.
Sloped slab
Also: ramp, uneven depth, tapered bed
V = L × W × (h₁ + h₂) ÷ 2
L = length, W = width, h₁ and h₂ = depth at each end.
Example: A dog run 20 × 4 ft that runs 4 in deep at the low end to 2 in at the top: 20 × 4 × (0.333 + 0.167) ÷ 2 = 20 cu ft = 0.74 cu yd.
For a French drain, subtract the space the pipe takes up: a 4 in pipe takes about 0.087 cu ft per foot of length (π × 0.167²), so 3.5 cu ft over 40 ft. The calculator’s “Hollow cylinder” shape works it out for any pipe size.
How deep should pea gravel be?
| Use | Typical depth | Notes |
|---|---|---|
| Decorative beds, around plants | 2 in | Over landscape fabric |
| Garden paths | 2–3 in | Use firm edging |
| Patios and seating areas | 3–4 in | Over a compacted crushed-stone base |
| Dog runs | 3–4 in | Easy to rinse and drains fast |
| French drains | Fill the trench | Around a perforated pipe, wrapped in fabric |
| Playground surfacing | Often 9 in or more | Depth depends on fall height; follow CPSC public playground guidance |
How much does a ton or a yard of pea gravel cover?
Use this to check a quote or see how far a delivery will go. The “Already have a load?” box in the calculator works it out for any amount.
| Depth | 1 ton covers | 1 cu yd covers | 50 lb bag covers |
|---|---|---|---|
| 1 in | ≈ 240 sq ft | 324 sq ft | ≈ 6 sq ft |
| 2 in | ≈ 120 sq ft | 162 sq ft | ≈ 3 sq ft |
| 3 in | ≈ 80 sq ft | 108 sq ft | ≈ 2 sq ft |
| 4 in | ≈ 60 sq ft | 81 sq ft | ≈ 1.5 sq ft |
| 6 in | ≈ 40 sq ft | 54 sq ft | ≈ 1 sq ft |
Weight of pea gravel and other stone
Stone weights vary with rock type, size and moisture. These typical values are what the calculator uses; ask your quarry for the exact number.
| Material | lb per cu ft | Tons per cu yd | Cu yd per ton |
|---|---|---|---|
| Pea gravel | ≈ 100 | ≈ 1.35 | ≈ 0.74 |
| Crushed stone | ≈ 100 | ≈ 1.35 | ≈ 0.74 |
| River rock | ≈ 100 | ≈ 1.35 | ≈ 0.74 |
| Gravel, dry | ≈ 105 | ≈ 1.42 | ≈ 0.71 |
| Gravel, wet | ≈ 125 | ≈ 1.69 | ≈ 0.59 |
Bags or bulk?
Bagged pea gravel is clean and easy to carry, but you need about 54 bags of 50 lb for one cubic yard. For a small bed or a few stepping-stone gaps, bags are fine. For a path or patio, bulk delivery is usually far cheaper per yard and spares your back; most suppliers deliver from about one or two yards, often with a delivery fee.
Worked examples
Patio with a path
A 12 × 12 ft patio at 4 in (48 cu ft) and a 30 × 3 ft path at 3 in (22.5 cu ft) add up to 70.5 cu ft = 2.61 cu yd, about 3.5 tons. With 5% extra, order 2¾–3 yards.
Fire-pit area
A circle 14 ft across, 3 in deep: 38.5 cu ft = 1.43 cu yd = 1.9 tons. Leave out the fire pit itself: a 4 ft pit removes about 3.1 cu ft.
French drain
A trench 12 in wide, 24 in deep and 40 ft long holds 80 cu ft. Minus a 4 in pipe (3.5 cu ft) leaves 76.5 cu ft = 2.83 cu yd, about 3.8 tons of washed gravel.
How to lay pea gravel so it stays put
- Dig out the area to your depth plus any base layer, and slope it slightly so water runs away from buildings.
- Compact the soil, then for patios add 2–4 in of crushed stone and compact that too.
- Lay landscape fabric to separate gravel from soil and slow weeds.
- Install edging (steel, stone, timber or pavers) a little higher than the finished gravel.
- Spread and rake the pea gravel to an even depth, then wet it down to settle it.
Notes for landscapers
Stabilizers. Honeycomb gravel grids keep pea gravel from rutting on paths and parking. Fill the grid and add about ½ in on top.
Drainage spec. For drains, ask for washed, clean stone with no fines, often ¾ in, so it doesn’t clog. Pea gravel works but has less void space when packed.
Settling. Rounded stone doesn’t compact like crushed stone, but it does settle 5–10% in the first months. Top up after a season.
Playgrounds. Required depths for safety surfacing depend on the critical fall height. Check the CPSC Public Playground Safety Handbook and the owner’s spec.
Tips
- Look at a sample wet and dry; colors change a lot when wet.
- Keep it away from doors or add a hard surface at entrances; pea gravel sticks in shoe soles.
- Need sand for pavers? Use the sand calculator.
- Send the order to your supplier with WhatsApp or Email under the result.
Frequently asked questions
How much pea gravel do I need?
Multiply length × width × depth in feet, divide by 27 for cubic yards and multiply by about 1.35 for tons. A 30 × 3 ft path at 3 in deep needs 22.5 cu ft, which is 0.83 cu yd or about 1.1 tons.
How much does a yard of pea gravel weigh?
About 2,600 to 2,800 lb, roughly 1.3 to 1.4 tons, when dry. The calculator uses about 2,700 lb (100 lb per cu ft) and you can enter your supplier’s figure as a custom density.
How much area does a ton of pea gravel cover?
A ton is about 20 cu ft. That covers about 120 sq ft at 2 in deep, 80 sq ft at 3 in and 60 sq ft at 4 in.
How deep should pea gravel be?
About 2–3 in for paths and decorative beds, 3–4 in for patios and dog runs, and much deeper (often 9 in or more) for playground safety surfacing, depending on the equipment height.
How many bags of pea gravel are in a yard?
A 50 lb bag usually holds about 0.5 cu ft, so a cubic yard is about 54 bags. Bags are handy for small areas; for more than about a yard, bulk is usually cheaper.
Is pea gravel good for a driveway?
Pea gravel is round, so it rolls and moves under tires and is hard to walk or push a wheelbarrow through. Angular crushed stone locks together and is the usual choice for driveways; pea gravel can be used as a top layer over a stable base, held in by edging.
Do I need landscape fabric under pea gravel?
Fabric over compacted soil helps keep the gravel from sinking into mud and slows weeds. A firm base and solid edging are just as important, because pea gravel spreads easily.
What size is pea gravel?
Usually about ⅛ to ⅜ in, with ⅜ in the most common size. The small, rounded stones are comfortable underfoot and drain well.
Is this pea gravel calculator free to use online?
Yes. The CalcWall Pea Gravel Calculator is completely free and works online in any browser, on a phone, tablet or computer. There is nothing to download and no account to create, and the math runs right in your browser, so results appear as you type.