Concrete Yardage Calculator
Knowing how much concrete a project requires is essential for planning materials, comparing prices, and reducing the risk of ordering too little or significantly too much. Because concrete projects come in many shapes and sizes, a simple length-by-width calculation is not always enough.
Our Concrete Yardage Calculator estimates concrete quantities for slabs, walls, footings, round columns or piers, and concrete stairs. It converts project measurements into cubic feet and cubic yards and can apply a 5%, 10%, or 15% waste factor. The calculator also estimates the equivalent number of 60 lb and 80 lb concrete bags, total concrete weight, and material cost based on the concrete price per cubic yard you enter.
Whether you are estimating a patio slab, foundation wall, continuous footing, concrete pier, or set of stairs, this tool can provide a useful preliminary concrete quantity estimate.
How to Use the Concrete Yardage Calculator
First, choose your project type. The calculator supports Slab, Wall, Footing, Column/Pier, and Stairs. The measurement fields will change according to your selection.
Enter all required dimensions carefully. Some measurements are entered in feet, while thickness, diameter, footing dimensions, stair rise, and stair run may be entered in inches.
Next, choose your waste factor. The calculator offers 5% for a minimal allowance, 10% as the standard option, and 15% for additional allowance. Enter the concrete price per cubic yard, then select Calculate.
Your results will include the original concrete volume in cubic feet and cubic yards, volume with the selected waste factor, estimated numbers of 60 lb and 80 lb bags, approximate total weight, and estimated concrete cost.
What Can This Concrete Yardage Calculator Estimate?
The tool accommodates several common concrete shapes.
For a slab, enter length and width in feet and thickness in inches. This can be useful for patios, walkways, floors, pads, and other rectangular slabs.
For a wall, enter its length and height in feet and thickness in inches.
For a footing, enter the total length in feet, followed by footing width and depth in inches.
For round columns or piers, enter diameter in inches, height in feet, and the total number of identical columns.
For concrete stairs, provide stair width in feet, rise and run per step in inches, and number of steps. The calculator models the increasing solid volume represented by the entered staircase dimensions.
Understanding Cubic Feet and Cubic Yards
Small measurements are often easier to calculate in cubic feet, but ready-mix concrete is typically quoted and ordered by the cubic yard.
There are exactly 27 cubic feet in one cubic yard because:
3 ft × 3 ft × 3 ft = 27 cubic feet
Therefore, after determining the volume in cubic feet, the calculator divides it by 27 to obtain cubic yards.
For example, a project containing 270 cubic feet requires:
270 ÷ 27 = 10 cubic yards
Before ordering concrete, the theoretical volume is usually considered alongside an appropriate allowance for actual job-site conditions.
How to Calculate Concrete Yardage for a Slab
A rectangular concrete slab requires three measurements: length, width, and thickness.
The basic calculation is:
Volume = Length × Width × Thickness
Because the calculator accepts slab thickness in inches, it first converts thickness to feet by dividing by 12.
Suppose you have a concrete slab measuring 20 feet long, 15 feet wide, and 4 inches thick. A 4-inch thickness equals approximately 0.333 feet.
The calculation is:
20 × 15 × 0.333 = 100 cubic feet
Convert cubic feet to cubic yards:
100 ÷ 27 = approximately 3.70 cubic yards
If a 10% waste factor is selected:
3.70 × 1.10 = approximately 4.07 cubic yards
That adjusted amount provides a more useful planning figure than relying only on theoretical volume.
Concrete Yardage Calculation Example
Consider a 24-foot-long by 20-foot-wide slab that is 6 inches thick.
Six inches equals 0.5 feet, so the slab volume is:
24 × 20 × 0.5 = 240 cubic feet
Convert this to cubic yards:
240 ÷ 27 = 8.89 cubic yards
With a 10% waste factor:
8.89 × 1.10 = 9.78 cubic yards
If ready-mix concrete costs $160 per cubic yard, the calculator estimates:
9.78 × $160 = approximately $1,564.44
The tool estimates total weight using 4,050 pounds per cubic yard of adjusted concrete, producing an approximate weight of 39,600 pounds.
These calculations can help establish a preliminary material budget before contacting a local ready-mix supplier.
Concrete Yardage for Walls
Concrete wall volume depends on wall length, wall height, and thickness.
For example, consider a wall that is 40 feet long, 8 feet high, and 8 inches thick. The 8-inch thickness converts to approximately 0.667 feet.
Its approximate volume is:
40 × 8 × 0.667 = 213.33 cubic feet
Dividing by 27 gives approximately 7.90 cubic yards before waste.
If your project contains several walls of different dimensions, calculate each section separately and combine the amounts as needed.
Door openings, window openings, pilasters, intersecting walls, and other structural features can affect actual concrete quantity.
Concrete Yardage for Footings
Footings are another common application for concrete volume calculations. Enter footing length in feet and its width and depth in inches.
For example, a 60-foot-long footing that is 24 inches wide and 12 inches deep converts to:
24 inches = 2 feet
12 inches = 1 foot
The volume is therefore:
60 × 2 × 1 = 120 cubic feet
That equals approximately 4.44 cubic yards before the selected waste factor.
Foundation footing sizes should be based on project plans and applicable structural and building requirements rather than chosen solely to reach a particular concrete quantity.
Estimating Concrete for Round Columns and Piers
Columns and piers require a different calculation because they are cylindrical rather than rectangular. The calculator uses the diameter to determine the radius and applies the volume formula for a cylinder.
For multiple identical piers, the volume of one cylinder is multiplied by the quantity entered.
This feature can be useful when estimating concrete for round piers, posts, or similar cylindrical placements. If your piers have enlarged bases or other shapes, calculate those additional portions separately because a simple cylinder calculation will not capture them.
Estimating Concrete for Stairs
Solid concrete stairs have a stepped geometry. Instead of treating the staircase as a single rectangular block, this calculator adds the volume of each successive step based on the width, rise, run, and total number of steps entered.
Stair construction can vary considerably. Some stairs are solid, while others may incorporate landings, foundations, supporting walls, voids, or other structural details. Use the result only when the calculator's stair geometry reasonably represents the planned project.
Why Add a Concrete Waste Factor?
A calculated geometric volume represents the ideal amount required to fill perfectly measured forms. Construction sites rarely match ideal dimensions exactly.
Subgrade variations, excavation tolerances, form movement, spillage, uneven surfaces, and other conditions can increase actual concrete use. A waste or contingency factor provides additional material above the basic calculated volume.
This calculator offers:
- 5% for a minimal allowance
- 10% for a standard allowance
- 15% for additional allowance
The correct amount is project-specific. A higher percentage is not automatically better, and these options should not replace the judgment of your contractor or concrete supplier.
60 lb and 80 lb Concrete Bag Estimates
For smaller projects, bagged concrete can be more practical than ordering a ready-mix truck.
The calculator estimates 60 bags of 60 lb concrete mix per theoretical cubic yard and 45 bags of 80 lb mix per theoretical cubic yard. Bag counts are rounded up to whole bags.
An important detail is that the calculator's bag estimates are based on the original calculated cubic yardage before the selected waste factor is applied. The waste-adjusted quantity is used separately for the weight and concrete cost calculations.
Actual bag yield varies by manufacturer and product formulation. Check the stated yield printed on the bag before purchasing materials. For the most accurate purchase estimate, use the manufacturer's specified yield and include any desired contingency.
How Is Total Concrete Weight Estimated?
The calculator uses an approximate concrete weight of 4,050 pounds per cubic yard and applies it to the volume after the selected waste factor.
Concrete density can vary based on the mix design, aggregates, moisture, and specialty materials. The displayed weight should therefore be treated as an approximate planning figure.
Weight estimates can be useful for understanding the scale of a project, but they should not be used by themselves to determine vehicle capacity, structural loading, lifting requirements, or transportation limits.
How Is Concrete Cost Calculated?
The estimated cost is calculated using the waste-adjusted cubic yardage multiplied by the price per cubic yard entered into the tool.
For example, if the adjusted requirement is 7.5 cubic yards and concrete costs $175 per cubic yard:
7.5 × $175 = $1,312.50
The result represents concrete material based on the entered per-yard rate. Your actual invoice can include delivery charges, short-load fees, minimum-order fees, fuel surcharges, pumping, taxes, specialty mix charges, waiting time, or other services.
Contact local ready-mix companies for current prices before creating a final construction budget.
Tips for Getting a More Accurate Concrete Estimate
Use actual project drawings or carefully measured dimensions whenever possible. Pay close attention to units because several calculator inputs use feet while others require inches.
For projects with different dimensions, divide the work into separate sections and calculate each section independently. For example, if one portion of a slab is thicker than another, calculate those areas separately.
Irregular excavation, thickened slab edges, grade beams, steps, columns, and other features may also need individual calculations.
Finally, confirm large ready-mix orders with your contractor or concrete supplier. The calculator provides a valuable planning estimate, but the supplier or project professional can account for site-specific factors that cannot be determined from dimensions alone.
Frequently Asked Questions
1. What is a Concrete Yardage Calculator?
A Concrete Yardage Calculator converts project dimensions into concrete volume, typically expressed in cubic feet and cubic yards. This tool also estimates waste-adjusted volume, bag quantities, weight, and cost.
2. How many cubic feet are in a cubic yard of concrete?
There are 27 cubic feet in one cubic yard. Divide cubic feet by 27 to calculate cubic yards.
3. What types of projects can I calculate?
The calculator supports rectangular slabs, walls, footings, round columns or piers, and concrete stairs.
4. How do I calculate concrete for a slab?
Multiply slab length by width and thickness after converting thickness from inches to feet. Divide the resulting cubic feet by 27 to get cubic yards.
5. Does the calculator include concrete waste?
Yes. You can select a 5%, 10%, or 15% waste factor. The adjusted volume is displayed separately from the theoretical cubic yardage.
6. What waste factor should I choose?
The appropriate factor depends on measurement accuracy, forms, excavation, subgrade conditions, placement method, and project complexity. The calculator offers 5%, 10%, and 15% as convenient estimating options.
7. How many 60 lb bags are estimated per cubic yard?
This calculator uses 60 bags of 60 lb concrete mix per cubic yard and always rounds the final bag count up to a whole bag.
8. How many 80 lb concrete bags are estimated per cubic yard?
The tool uses 45 bags of 80 lb concrete mix per cubic yard. Actual product yields vary, so check the concrete mix manufacturer's packaging before buying.
9. Do the bag estimates include the selected waste factor?
No. The tool calculates 60 lb and 80 lb bag quantities from the original concrete volume before applying the selected waste factor.
10. How does the calculator estimate concrete weight?
The waste-adjusted concrete volume is multiplied by approximately 4,050 pounds per cubic yard.
11. How is concrete price calculated?
The calculator multiplies the waste-adjusted cubic yardage by the price per cubic yard that you enter.
12. Does the total cost include labor and delivery?
No. The result is based only on waste-adjusted concrete volume and your entered price per cubic yard. Labor, delivery, pumping, reinforcement, taxes, and other expenses are not separately included.
13. Can I calculate multiple concrete columns?
Yes. Enter the column diameter, height, and number of identical columns or piers. The calculator combines their volumes.
14. Can I use the calculator for concrete stairs?
Yes. Enter stair width, rise per step, run per step, and number of steps. The estimate assumes the stepped solid geometry used by the calculator, so more complex stair structures may need additional calculations.
15. Can I order concrete directly from the calculator result?
The result is useful for preliminary estimating, but confirm the final quantity with your contractor or ready-mix supplier. Site conditions, supplier order increments, waste allowance, and project geometry can affect the amount that should actually be ordered.