Convert length, width, and depth into cubic yards for concrete, mulch, and gravel orders. Free with steps.
Bulk materials — concrete, topsoil, mulch, gravel, road base — are sold by the cubic yard, not by the bag or the truckload. One cubic yard is a cube 3 feet on each side: 27 cubic feet of material. Our free Cubic Yards Calculator turns your length, width, and depth into cubic yards, shows the exact cubic footage, and even suggests an order quantity with a 7% waste allowance rounded up to the quarter yard, the way suppliers actually invoice.
Ordering by the yard is where DIY projects most often go wrong. A patio slab that is 12 ft by 10 ft and 4 inches thick needs 1.48 cubic yards of concrete — order 1.5 and you are short by a wheelbarrow; order 2 and you paid for half a yard of waste. The calculator removes the guesswork by doing the division by 27 for you and adding the waste factor contractors actually use.
Use feet, inches, or yards for your measurements; the tool normalizes everything to feet first. The result is exact for rectangular areas — slabs, beds, trenches, and footings — and a solid planning figure for anything close to rectangular.
A cubic yard (yd³) is the volume of a cube measuring one yard — three feet — on each edge. Because 3³ = 27, one cubic yard equals exactly 27 cubic feet, or 46,656 cubic inches. Picture a washing machine: most full-size washers occupy roughly one cubic yard.
The cubic yard became the bulk-material standard because it matches the equipment. A typical ready-mix concrete truck carries 8–10 cubic yards; a tri-axle dump truck hauls 12–16 cubic yards of gravel. Pricing, delivery minimums, and short-load fees are all quoted per yard, so every estimate you make must end in cubic yards to be comparable with quotes.
Weight and volume are different things, and suppliers price volume while trucks are limited by weight. A cubic yard of concrete weighs about 4,000 lb; a cubic yard of dry topsoil about 2,000 lb; a cubic yard of shredded mulch only 400–600 lb. That is why a “yard” of mulch arrives as a fluffy mountain while a yard of concrete arrives as a dense, modest pile — same volume, wildly different mass.
Key terms:
The classic site shortcut: square footage times depth in inches, divided by 324, also gives cubic yards — because 27 × 12 = 324. A 400 ft² slab at 4 inches: 400 × 4 ÷ 324 = 4.94 yd³.
A patio slab is 12 ft long, 10 ft wide, and 4 inches thick.
With 7% waste: 1.48 × 1.07 = 1.58 → order 1.75 yd³ (rounded to the quarter). Most plants have a 2-yard minimum, so expect a short-load fee or plan a second small pour.
A landscape bed measures 20 ft by 6 ft, and you want 3 inches of mulch.
Order 1.25 yd³. Bagged mulch (2 ft³ bags) would need 15 bags; bulk delivery at 1.25 yards is usually cheaper once you pass about 10 bags.
Marcus is extending his driveway: 24 ft long, 10 ft wide, 6 inches of compacted road base topped with 4 inches of concrete. The base volume is 24 × 10 × 0.5 ft = 120 ft³ = 4.44 yd³; the concrete is 24 × 10 × 0.333 = 80 ft³ = 2.96 yd³. With waste, he orders 5 yards of base and 3.5 yards of concrete. The base arrives by dump truck (one load), the concrete by ready-mix (one short load). His quote comparison is apples-to-apples because every supplier bid in cubic yards.
The subgrade surprise is the lesson. After excavation, Marcus finds soft spots that need another 2 inches of base in places. Because he computed the exact yardage (4.44) and ordered 5, the extra half yard covers it — the waste factor did its job. Contractors who skip the waste factor end up paying a second delivery fee that dwarfs the cost of the extra half yard.
A second scenario: raised garden beds. Three beds, each 8 ft × 4 ft × 1 ft deep, need 3 × 32 = 96 ft³ = 3.56 yd³ of soil mix. Bulk soil at $45/yard totals $160; the bagged equivalent (48 bags at 2 ft³) would cost over $380 and a full day of hauling. The cubic-yard calculation is what makes the bulk-versus-bag decision obvious.
Ready-mix concrete is the strictest cubic-yard discipline because it is perishable. Once water hits cement, you have about 90 minutes. Plants batch to the tenth of a yard, and the ticket on the truck states the exact yardage. Experienced foremen compute the pour three ways — by the calculator, by the 324 shortcut, and by counting wheelbarrow loads (about 9 per yard) — because running short mid-pour creates a cold joint, a structural weak plane where new concrete meets concrete that has begun to set.
Topsoil and compost introduce the compaction factor. A yard of fluffy delivered soil settles to about 0.8 yards after rain and foot traffic. Bed calculations should therefore target the settled depth: for a final 6-inch bed, order for 7–8 inches of loose fill. Mulch behaves oppositely — it fluffs up — so a yard of mulch covers more area at 3 inches than the math predicts, typically 100–110 ft² instead of the theoretical 108.
Gravel and crushed stone add the void ratio. Loose aggregate is roughly 40% air; compacted, about 25%. A 4-inch loose layer compacts to under 3 inches. Road builders order by compacted depth and add 25–30% for compaction loss, which is why the road-base entry in this batch uses a dedicated density factor rather than raw volume.
Finally, the bag-to-yard bridge: a 60 lb bag of concrete mix yields 0.45 ft³; an 80 lb bag yields 0.6 ft³. One cubic yard needs 60 sixty-pound bags or 45 eighty-pound bags — at which point the ready-mix truck is cheaper, faster, and far kinder to your back. The crossover is usually around half a yard: below it, bags; above it, bulk.
Cubic yards = (length × width × depth in feet) ÷ 27. Shortcut: ft² × inches of depth ÷ 324. Order quantity ≈ exact yd³ × 1.07, rounded up to 0.25 yd. 1 yd³ = 27 ft³ = 46,656 in³. Billing unit for concrete, soil, mulch, gravel. Source: Sigma Calculator, Cubic Yards Calculator, https://sigmacalculator.net/math-calculators/cubic-yards-calculator/
Cite this page as: Cubic Yards Calculator, Sigma Calculator, https://sigmacalculator.net/math-calculators/cubic-yards-calculator/
Last updated: October 12, 2026