Pea Gravel Calculator
Pea gravel is one of those materials where the math is easy and the buying decision is where people lose money. The volume calculation takes thirty seconds: area times depth, converted to cubic yards. But then you stand in the garden center looking at a wall of 0.5 cu ft bags at $5 each, and the real question hits — do I haul home 66 bags, or call the landscape yard for a bulk delivery? Bagged pea gravel works out to roughly $240–480 per ton. Bulk from a landscape supplier runs about $25–55 per ton. Same stones, up to ten times the price. This pea gravel calculator gives you both numbers that matter: exactly how much gravel your project needs — in cubic yards, tons and bags — and the bag count that tells you when to stop buying bags and start calling yards. It works in feet and inches or metres and centimetres, for rectangles and circles, and it is honest about the one number every gravel website disagrees on: density.
How to use this calculator
- Measure the length and width of the area in feet (or metres). For a round bed or tree ring, measure straight across — that diameter goes in the length box, and you can ignore width.
- Decide the depth. Patios and walkways want 2–3 inches (5–8 cm); garden beds 1–2 inches; playgrounds 9–12 inches per safety guidance. When in doubt, go a touch deeper — thin gravel shows the base through it within a season.
- Enter the numbers and pick your shape. Rectangles use length × width; circles use π × (diameter ÷ 2)².
- Check the density setting. The default 1.4 tons per cubic yard suits most pea gravel; pick 1.35 if your supplier quotes light, dry stone, or 1.5 for heavy, wet loads.
- Read the three outputs: cubic yards (what bulk yards sell by), tons (what delivery tickets and dump trailers use), and bag count (what the garden center sells).
- Use the bag count to make the real decision: under about 20–25 bags, bags are fine. Above that, call a landscape yard — bulk is dramatically cheaper and they deliver.
- Order with the waste allowance included, and confirm the density with your supplier when you call — their scale beats any website, including this one.
Formula
Worked example
Take a 12 × 10 ft patio at 3 inches deep. Step one — area: 12 × 10 = 120 sq ft. Step two — cubic feet: 120 × 3 ÷ 12 = 30 cu ft. Step three — cubic yards: 30 ÷ 27 = 1.11, plus 10% for settling: 1.22 yd³. Step four — tons: 1.22 × 1.4 = 1.71 tons. Step five — bags: 30 × 1.10 ÷ 0.5 = 66 bags. Now the decision: 66 bags at $5 each is $330 of hauling, loading and ripping plastic — or about 1.7 tons bulk at $25–55/ton, roughly $45–95 plus a delivery fee. That phone call to the landscape yard just saved you a couple hundred dollars.
Metric version: a 4 × 3 m bed at 8 cm deep. Area: 4 × 3 = 12 m². Volume: 12 × 0.08 = 0.96 m³, plus 10% = 1.06 m³. Weight: 1.056 × 1.66 = 1.75 tonnes (1,754 kg). Bags: 1,754 ÷ 25 = 71 × 25-kg bags. Same verdict — 71 bags is a bulk-delivery job.
Measurement tips
- Put landscape fabric down first, over a compacted base. It stops weeds pushing through and keeps the gravel from sinking into soft soil — the two things that ruin a gravel patio fastest.
- Edge it or lose it. Pea gravel migrates — feet, rain and mowers scatter it. Steel, stone or timber edging a couple of inches above the gravel line keeps it where you put it.
- Order the waste allowance. Gravel settles about 10% after the first rains, and you will spill some spreading it. Running short mid-project means a second delivery fee.
- For paths, 2 inches is the minimum that hides the base; 3 inches feels better underfoot and stays put longer. Go 4 inches only if the ground underneath is soft.
- Ask the yard what their density is when you order. If they say "about a ton and a half a yard," re-run the calculator at 1.5 — their ticket is what you pay, not our default.
- Spread in two lifts for deep beds. Dumping 6 inches at once and raking it level leaves soft spots; two 3-inch layers, each raked and lightly compacted, sit flatter.
Common mistakes
- Going too shallow. One inch of pea gravel over dark soil looks fine on day one and patchy by month three — the base shows through wherever feet land. Two inches minimum for beds, three for patios.
- Skipping the edging. This is the single most common regret: without a border, gravel creeps into the lawn a little more every week until you are buying a second load.
- Using pea gravel for a driveway. The round stones roll under tires, rut, and migrate to the edges. Crushed stone with angular faces locks together — pea gravel never will.
- No landscape fabric. Weeds come up through 3 inches of gravel like it is not there, and on clay soil the stones press down into the mud and vanish.
- Ordering the exact calculated amount. Between settling, spillage and the odd low spot, exact orders come up short — the 10% allowance exists for a reason.
- Buying 60+ bags instead of calling a yard. At $4–8 per bag versus $25–55 per ton bulk, the crossover is around half a cubic yard. Sixty-six bags is not a shopping trip, it is a delivery.
Factors that affect accuracy
- Depth. It multiplies everything — going from 2 to 3 inches adds 50% more gravel. Measure depth honestly; most people underestimate it.
- Area shape. Circles waste less to edging but the πr² math surprises people — a 10 ft diameter circle is only 78.5 sq ft, not 100.
- Density. The 1.35–1.5 range swings tonnage by about 10% either way. It matters for delivery weight limits, not for the shovel work.
- Settling and compaction. Fresh gravel sits fluffy, then rain and feet pack it down ~10%. Soft or freshly tilled soil eats more — budget 15–20% extra there.
- Waste in handling. Every transfer — bag to wheelbarrow to bed — spills a little. It adds up over 60 bags.
- Delivery minimums. Many yards have a 1–2 ton minimum or a flat delivery fee ($50–150), which changes the bags-vs-bulk math for small jobs — ask before you assume.
Sources & assumptions
- Volume = length × width × depth; tons = cubic yards × density (1.4 default; honest supplier range 1.35–1.5).
- Bag math: 0.5 cu ft bags = cubic feet × 1.10 ÷ 0.5; 25-kg bags = kilograms ÷ 25 — both rounded up.
- Density and project-depth table per PeaGravelCalculator.com (USGS 100 lb/ft³ ≈ 1.35 t/yd³); 1.35 t/yd³ and 54 bags/yd³ per PeaGravelCalculators.com.
- Bulk-vs-bag cost crossover (~0.5 yd³) and depth guidance per Angi's pea gravel guide; worked examples method per Eartheasy.
What this calculator doesn't do
- Gravel density genuinely varies by supplier — 1.35 to 1.5 tons per cubic yard is the honest range, and this calculator uses 1.4. Always confirm density with your supplier, because their scale is what you are billed on.
- It estimates material quantity only — it doesn't design drainage, check soil bearing, or confirm playground safety depths. For play areas, check current CPSC guidance on fall-surface depths.
- Bag counts assume standard 0.5 cu ft (US) or 25 kg bags; actual bag sizes vary by brand and country, so check the bag label.
- Prices in this article are US ranges for context only — gravel pricing is regional everywhere, so get a local quote before budgeting.
Frequently asked questions
How much pea gravel do I need for a 10×10 area?
At 3 inches deep: 10 × 10 = 100 sq ft, × 3 ÷ 12 = 25 cu ft = 0.93 cubic yards, about 1.3 tons, or 50 standard 0.5 cu ft bags. At 2 inches deep it drops to 0.62 yd³ (0.87 tons, 34 bags). Enter your exact depth above — depth is the number most people guess wrong.
How many bags of pea gravel are in a cubic yard?
About 54 bags, if they are 0.5 cu ft bags and the gravel weighs 2,700 lb per cubic yard (1.35 tons). The count shifts with bag size and density — a 0.4 cu ft bag needs 68 per yard. Check the bag label and divide 27 by the bag volume in cubic feet for your exact number.
What depth of pea gravel do I need for a patio or walkway?
2–3 inches (5–8 cm) over landscape fabric on a compacted base. Two inches is the minimum that hides the base; three feels better and lasts longer. Garden beds can go 1–2 inches; playgrounds need 9–12 inches per safety guidance.
Can I use pea gravel for a driveway?
Not loose, no. The round stones roll under tires, develop ruts, and migrate to the edges — you will be raking it back weekly. Use crushed stone (angular faces lock together) or pea gravel contained in honeycomb stabilization grids if you love the look.
How many tons of pea gravel are in a cubic yard?
Between 1.35 and 1.5 tons, depending on the stone source and moisture — this is the number gravel websites disagree on. We use 1.4 as a middle value. Your supplier's scale is the final answer: ask them their tons-per-yard when you order.
Do I need landscape fabric under pea gravel?
Yes. It does two jobs: stops weeds growing up through the gravel, and stops the stones sinking into soft soil and disappearing. Lay it over compacted, level ground and overlap seams by several inches.
Should I buy pea gravel in bags or bulk?
Bags win under about half a cubic yard (roughly 25 bags) — no delivery fee, no minimum. Above that, bulk wins by a landslide: bagged gravel runs $240–480 per ton versus $25–55 per ton bulk. A 66-bag patio is around $330 in bags versus under $100 bulk plus delivery.
How much area does one ton of pea gravel cover?
One ton is about 0.71 cubic yards (19.3 cu ft at 1.4 tons/yd³): roughly 77 sq ft at 3 inches deep, 116 sq ft at 2 inches, or 231 sq ft at 1 inch. In metric, one tonne covers about 7.5 m² at 8 cm deep.
Next step
Take the cubic-yard and ton totals to the landscape yard — and ask their tons-per-yard figure, since their scale is what you pay on. If the bag count is over 25, get a bulk quote before buying a single bag.
Save this estimate: use the Copy link button in the results box above to share these exact inputs, or Print results for a paper copy to take to the store.