Concrete Yard Calculator

Determining exactly how many cubic yards of concrete to order from a commercial ready-mix dispatch requires translating tape measurements into cubic y

Construction

Length — Feet (ft)

Whole feet portion of length

Length — Inches (in)

Inches portion of length (e.g. 6 for 12 ft 6 in)

Width — Feet (ft)

Whole feet portion of width

Width — Inches (in)

Inches portion of width

Slab Thickness (in)

Uniform slab thickness in inches (4 in = 0.3333 ft)

Waste & Subgrade Allowance

Reserve for subgrade variance and truck chute residue (10% standard)

Formula & Methodology

Length (ft) = Feet + (Inches ÷ 12) Width (ft) = Feet + (Inches ÷ 12) Depth (ft) = Thickness (in) ÷ 12 Volume (cu yd) = (Length ft × Width ft × Depth ft) ÷ 27 Ordered Yards = ⌈Volume (cu yd) × (1 + Waste % ÷ 100) ÷ 0.25⌉ × 0.25

A tape reading of 12 ft 6 in represents 12.5 feet, not 12.6 feet. Treating inches as decimal fractions understates volume. The tool normalizes paired feet and inches into true decimal feet, converts thickness to feet (in ÷ 12), and divides cubic feet by 27 to produce exact cubic yards. Ready-mix suppliers dispense in batch increments (typically 0.25 or 0.5 cu yd); the tool rounds strictly UP to prevent cold joint failures.

Ready-Mix Yards to Order (Rounded Up)

1.75 cu yd

Overview

Determining exactly how many cubic yards of concrete to order from a commercial ready-mix dispatch requires translating tape measurements into cubic yardage and rounding up to the supplier batch increment. This Concrete Yard Calculator handles paired feet and inches measurements without decimal transcription errors and applies practical supplier rounding.

Estimates are for material planning and budgeting purposes only. This calculator does not provide structural engineering, architectural design, or official building code compliance advice. Always verify measurements, local building codes, and permit requirements with a licensed contractor or local building authority before purchasing materials or commencing construction.

Worked Examples

Example 1: Tape Measure Input (12 ft 6 in × 10 ft at 4 in with 10% Waste - Check Case)

Inputs: Length = 12 ft 6 in, Width = 10 ft 0 in, Thickness = 4 in, Waste = 10%

Normalize length: 12 ft + (6 in ÷ 12) = 12.50 ft.
Normalize width: 10 ft + 0 in = 10.00 ft.
Convert thickness: 4 in ÷ 12 = 0.3333 ft.
Calculate net cubic feet: 12.5 ft × 10 ft × 0.3333 ft = 41.67 cu ft.
Convert to cubic yards (divide by 27): 41.667 cu ft ÷ 27 = 1.5432 cu yd.
Add 10% waste buffer: 1.5432 cu yd × 1.10 = 1.6975 cu yd.
Round UP to next 0.25 cu yd truck increment: 1.75 cu yd.

Final Answer: 1.75 cu yd to order (1.54 net cu yd; exact unrounded requirement: 1.70 cu yd)

Example 2: 20 ft × 10 ft Garage Apron at 5 in Thick with 10% Waste

Inputs: Length = 20 ft 0 in, Width = 10 ft 0 in, Thickness = 5 in, Waste = 10%

Normalize dimensions: 20.00 ft length × 10.00 ft width.
Convert depth: 5 in ÷ 12 = 0.4167 ft.
Calculate volume in cubic feet: 200 sq ft × 0.4167 ft = 83.33 cu ft.
Convert to cubic yards: 83.33 cu ft ÷ 27 = 3.0864 cu yd.
Add 10% waste allowance: 3.0864 cu yd × 1.10 = 3.3951 cu yd.
Round UP to next 0.25 cu yd truck increment: 3.50 cu yd.

Final Answer: 3.50 cu yd to order (3.09 net cu yd + 0.31 waste reserve; 3.50 cu yd rounded order)

Example 3: 24 ft 6 in × 12 ft Patio at 4 in Thick with 8% Waste

Inputs: Length = 24 ft 6 in, Width = 12 ft 0 in, Thickness = 4 in, Waste = 8%

Normalize length: 24 + (6 ÷ 12) = 24.50 ft.
Normalize width: 12.00 ft; Area = 294.00 sq ft.
Convert thickness: 4 in ÷ 12 = 0.3333 ft.
Volume: 294 sq ft × 0.3333 ft = 98.00 cu ft ÷ 27 = 3.6296 cu yd.
Add 8% waste factor: 3.6296 cu yd × 1.08 = 3.9200 cu yd.
Round UP to next 0.25 cu yd batch: 4.00 cu yd.

Final Answer: 4.00 cu yd to order (3.63 net cu yd + 0.29 waste buffer; 4.00 cu yd rounded)

How to Use This Calculator

Enter your measured length separated into whole feet and remaining inches from your tape measure.

Enter your measured width in feet and inches.

Specify slab thickness in inches (e.g. 4 inches for sidewalks or 5 inches for aprons).

Set your desired waste factor (10% is standard to guarantee you do not run short).

Review the normalized decimal feet echo, exact yardage, and the recommended rounded ready-mix truck order.

Reference Table

Tape Measurement	Decimal Feet	Thickness	Exact cu yd (10% Waste)	Ready-Mix Order
12 ft 6 in × 10 ft	12.5 × 10.0 ft	4 in	1.70 cu yd	1.75 cu yd
15 ft 6 in × 10 ft	15.5 × 10.0 ft	4 in	2.11 cu yd	2.25 cu yd
18 ft 9 in × 12 ft	18.75 × 12.0 ft	4 in	3.06 cu yd	3.25 cu yd
20 ft 0 in × 10 ft	20.0 × 10.0 ft	5 in	3.40 cu yd	3.50 cu yd
24 ft 6 in × 12 ft	24.5 × 12.0 ft	4 in	3.92 cu yd	4.00 cu yd
30 ft 0 in × 15 ft	30.0 × 15.0 ft	4 in	6.11 cu yd	6.25 cu yd

Frequently Asked Questions

Why is 12 ft 6 in entered as 12.5 ft instead of 12.6 ft?

There are 12 inches in a foot, not 10. Six inches equals 6 ÷ 12 = 0.50 of a foot. Writing 12.6 feet would equal 12 feet 7.2 inches, which distorts area and volume calculations. The calculator normalizes tape readings automatically.

What is a short-load fee and how do I avoid it?

Ready-mix companies charge a short-load fee (typically $100 to $250) when dispatching trucks with less than their minimum capacity (usually 4 to 5 cubic yards). Combining pours or ordering full batch increments minimizes these charges.

What is a cold joint and why does running out of concrete cause it?

A cold joint occurs when fresh concrete is placed against previously poured concrete that has already begun to set and stiffen. The two batches fail to interlock chemically, creating a permanent structural crack and water intrusion plane.

Does the waste factor cover truck chute washout residue?

Yes. Ready-mix trucks retain roughly 0.1 to 0.2 cubic yards of wet concrete adhering to internal drum fins and delivery chutes that cannot be completely discharged. A 10% allowance covers this residue.

Can I return unused concrete to the ready-mix truck driver?

You cannot get a refund for excess wet concrete ordered. Once dispatched in the transit mixer, the batch must be washed out at the plant or on-site. It is always better to have half a yard extra than half a yard short.