Pea gravel: How Deep and How Much
Published density and depth figures for pea gravel, each with its source shown — where sources disagree, we list both instead of averaging. All sources also on the methodology page.
Density (as published)
| As stated | Density | Source |
|---|---|---|
| Pebbles (3/8" pea) | 2,700 lb/cu yd | TRORC Material Weight Chart |
| Pea Gravel | 2,565 lb/cu yd | CalculatorSoup Gravel Calculator density table |
| 1B Pea Gravel | 2,410 lb/cu yd | GravelShop.com product calculator |
| Generic dry gravel range (95-105 lb/cu ft), not pea-gravel-specific | 2565-2835 lb/cu yd | GigaCalculator Gravel Calculator, citing Nemati, K.M. |
How deep
| Use | Depth | Source |
|---|---|---|
| walkway/path (general gravel, not pea-specific) | 2–4 in | UC ANR |
| decorative/mulch bed | 2–2.5 in | HomeToSight - How Deep Should Landscape Rock Be |
A 100 sq ft area at 3 inches needs about 0.93 cubic yards — 1.12 to 1.26 tons depending on which cited density you use. Formula: sq ft × depth ÷ 324; tons = yards × density ÷ 2,000.
Run your own dimensions through the gravel calculator
How rounded materials behave
Rounded materials, such as pea gravel and river rock, form through water action rather than mechanical crushing. UC ANR (UC Master Gardener) gives pea gravel as its example of "river-run" gravel: it never packs down completely, and the rounded pieces slip and slide underfoot, which makes it hard to walk on or to set furniture on. River rock behaves the same way in UC ANR's guidance, staying loose unless large stones are worked in to give it support.
Because rounded gravel doesn't lock together, it spreads. UC ANR recommends an edging border, using bender board, plastic edging, rock, pavers, brick, or lumber, to keep pea gravel and river rock from migrating into the soil beside a bed or path.
That loose behavior steers rounded gravel toward decorative beds, ground cover, and drainage features rather than hard-traffic paths. HomeToSight lists 2 to 2.5 inches for a pea gravel mulch bed and 2 to 3 inches for a river rock flower bed. For a dry creek bed or other drainage feature, HomeToSight calls for 3 to 4 inches of river rock, the same range it gives for a river rock walkway, and 4 inches or more for a river rock driveway. UC ANR's own walkway figure for gravel generally is a 2-inch practical minimum, extended to 4 inches where thicker stones or pavers are worked in.
What the sources say
- River-run gravel (pea gravel is the given example) never packs down completely into a solid surface; pieces slip and slide, making it difficult to walk on or place furniture on. Better suited as mulch/ground cover than as a hard-traffic path base unless large stones are added for support. (UC ANR)
- To keep gravel from migrating into adjacent soil, use an edging border (bender board, plastic edging, rock, pavers, bricks, or lumber). Landscape fabric underneath is debated: it suppresses weeds growing up from below but does nothing to stop weed seeds landing on top of the gravel from germinating, and it keeps gravel from mixing into the soil below as long as it stays intact. (UC ANR)
- Rule of thumb: one ton of gravel covers 80 to 120 square feet at 2 inches of depth. (UC ANR)
Common questions
How many tons is a cubic yard of pea gravel?
1.21 to 1.35 tons per cubic yard across the cited figures above. Suppliers weigh loads at the scale, so their ticket beats any table.
Why do the density figures disagree?
Moisture, stone size, and compaction all move the number, and some retail calculators reuse one site-wide default. We show each source's figure with attribution so you can see which kind of source it is.
Planning estimates from the cited figures, as of 2026-07-13. Your supplier's scale ticket and your soil conditions decide the real number.