How many yards of concrete do I need?

Multiply length by width by thickness in feet, divide by 27, and add 4 to 10 percent overage. An 18 by 24 foot driveway at 6 inches is 8.0 cubic yards, 8.8 with 10 percent, ordered as 9.0 after rounding to the quarter yard. The calculator returns the order quantity, truck count, and delivered cost for the dimensions you enter.

How many yards of concrete are in a truck?

A standard transit mixer carries 8 to 12 cubic yards, per NRMCA CIP 31, so most residential driveways and slabs are a single truck. Plan back-to-back loads past about 10 yards, and stage the pour so each truck discharges before the last load sets.

How much extra concrete should I order?

NRMCA CIP 31 calls for 4 to 10 percent over the plan estimate, to cover spillage, form spread, and an uneven subgrade. The calculator defaults to 10 percent. Ordering to the exact plan number is the most common reason a pour comes up short and needs a cold joint or a half-yard second truck.

What is the minimum amount of concrete you can order?

Most plants set a minimum around 3 cubic yards and charge a short-load fee of 50 to 150 dollars on smaller loads. Under about a cubic yard, bagged concrete is usually cheaper than the truck plus the fee. The calculator flags the short-load threshold and points sub-yard pours to the bag count.

MATERIALFOREMAN · SHEET C-004 · CONCRETE WORKS

CALC-004 · DRAWING NO. C-004 · REV A

Yards of concrete calculator.

Drafted to scale · cited sources · honest numbers

Enter the slab or driveway dimensions. The calculator returns cubic yards, the quantity to order rounded up to the quarter yard plants batch in, ready-mix truck loads, and a delivered-cost range. Built for ordering a truck, not hand-mixing bags. Overage follows the NRMCA 4 to 10 percent rule.

◈ DRAFTING PANEL · CONCRETE TAKEOFF · N.T.S. SHEET C-004 · REV A

Redline · scope notice Ready-mix ordering only. Returns volume and truck loads for a rectangular slab, driveway, or footing. Does not size rebar, mesh, forms, or subgrade, and does not specify the mix design (strength, slump, air entrainment). Rectangles only; sum L-shapes and odd bays as separate runs. For pours under a cubic yard, the bag page sizes the hand-mix alternative.

Note 01 · Field Procedure

How to order the yards

Square the forms and record length and width in feet, inside the form boards. Round up to the nearest half foot for irregular edges.
Measure thickness in inches, from the top of the compacted gravel base to the top of the form board. Thickness is inches, not feet: a 6 in driveway is 6, not 0.5.
Add the overage. NRMCA CIP 31 calls for ordering 4 to 10 percent over the plan estimate for spillage, subgrade variation, and form spread. The calculator defaults to 10.
Round up to the quarter yard. Plants batch and sell in 1/4 yd³ steps, so the order quantity rounds the volume up to the next quarter yard.
Check the subgrade for a crown. If the middle dips, the slab is thicker than the forms read and the load runs short. Add half an inch to thickness if it does.

Note 02 · Equation

The formula

yd³ = ( L × W × T ) ÷ 324 × ( 1 + waste ÷ 100 )

L, Wlength and width in feet

Tthickness in inches

324ft³→yd³ factor for T in inches (12 × 27)

wasteoverage, NRMCA 4-10% (defaults to 10)

Order quantity rounds yd³ up to the next 1/4 yard. Trucks = yd³ ÷ 10, rounded up, since a transit mixer carries 8 to 12 yd³.

Note 03 · Sanity Ranges

Ordering by project size

T	Use case	Notes
~3 yd³	Apron / small pad	The smallest most plants deliver without a short-load fee.
~6 yd³	Two-car driveway, 4 in	One truck. A 20 by 24 pad lands here with overage.
~9 yd³	Driveway, 6 in	An 18 by 24 driveway. One full truck with room to spare.
12+ yd³	Foundation / large slab	Past one truckload (8 to 12 yd³). Schedule back-to-back loads.

Note 04 · References

Sources

Authorities cited on this sheet

NRMCA CIP 31: Ordering Ready Mixed Concrete · National Ready Mixed Concrete Association, verbatim: concrete is sold by volume in cubic yards; truck mixer capacity is 8 to 12 cubic yards; quantity ordered should be 4% to 10% more than the plan estimate. The basis for the order increment, truck count, and overage.
ACI 332-20: Residential Code Requirements for Structural Concrete · American Concrete Institute. Minimum slab thicknesses and aspect-ratio limits for residential concrete. The ACI store page is the canonical link.
QUIKRETE 80 lb Concrete Mix Technical Data Sheet (DS 1101) · Yield 0.60 ft³ per 80 lb bag, the basis for the bag-count fallback shown when a pour lands under the ready-mix minimum.
NRMCA Concrete in Practice information series · The full Concrete in Practice library, including short-load fees, delivery scheduling, and truck access for residential pours.

Note 05 · Field Manual

What the sheet count does not tell you

An 18 by 24 driveway, worked out

Take a two-car driveway: 18 by 24 feet, poured 6 inches thick. Volume is length times width times thickness in feet, so 18 times 24 times half a foot is 216 cubic feet, which is 8.0 cubic yards. Add the 10 percent overage and it is 8.8 yards. Plants sell in quarter-yard steps, so the order rounds up to 9.0 yards. That is one truck with room to spare, since a transit mixer carries 8 to 12 yards. Delivered, the concrete runs about 1,188 to 1,540 dollars before any pump or short-notice fees. Hand-mixing is not on the table at this size: the same pour is close to 400 bags of 80 pound mix.

Ordering in yards: overage and the quarter yard

Ready-mix is sold by volume, in cubic yards, per NRMCA CIP 31. Two adjustments turn a plan volume into an order. First, overage: the same CIP calls for ordering 4 to 10 percent more than the plan dimensions to cover spillage, a spreading form, and a subgrade that is never perfectly flat. Order to the exact plan number and the last few feet of the pour come up short, which means a cold joint or a second truck for half a yard. Second, the increment: plants batch in quarter-yard steps, so an 8.8 yard volume is ordered as 9.0. The calculator applies the overage, then rounds up to the next quarter yard, and prints the number to give the dispatcher.

Trucks, minimums, and access

A standard transit mixer holds 8 to 12 cubic yards, so most residential pours are one truck. Past about 10 yards, the job needs back-to-back loads, and the pour has to be staged so the second truck discharges before the first load sets. At the small end, plants set a minimum, usually around 3 yards, and add a short-load fee of 50 to 150 dollars below it. The other constraint is access. A loaded concrete truck weighs about 80,000 pounds and cannot cross a soft lawn, a thin residential curb, or a buried septic field without risk. If the truck cannot reach the forms, the pour needs a pump, wheelbarrows, or a buggy, and that decision belongs in the order, not the morning of.

Note 06 · Common Questions

Common questions

How many yards of concrete do I need?: Multiply length by width by thickness in feet, divide by 27, and add 4 to 10 percent overage. An 18 by 24 foot driveway at 6 inches is 8.0 cubic yards, 8.8 with 10 percent, ordered as 9.0 after rounding to the quarter yard. The calculator returns the order quantity, truck count, and delivered cost for the dimensions you enter.
How many yards of concrete are in a truck?: A standard transit mixer carries 8 to 12 cubic yards, per NRMCA CIP 31, so most residential driveways and slabs are a single truck. Plan back-to-back loads past about 10 yards, and stage the pour so each truck discharges before the last load sets.
How much extra concrete should I order?: NRMCA CIP 31 calls for 4 to 10 percent over the plan estimate, to cover spillage, form spread, and an uneven subgrade. The calculator defaults to 10 percent. Ordering to the exact plan number is the most common reason a pour comes up short and needs a cold joint or a half-yard second truck.
What is the minimum amount of concrete you can order?: Most plants set a minimum around 3 cubic yards and charge a short-load fee of 50 to 150 dollars on smaller loads. Under about a cubic yard, bagged concrete is usually cheaper than the truck plus the fee. The calculator flags the short-load threshold and points sub-yard pours to the bag count.

PROJ MATERIALFOREMAN

SHT C-004 / 014

REV A · 2026-06-07

DRAWN MF