Introduction
Ordering too much or too little concrete is a costly mistake. This concrete calculator helps you figure out exactly how much concrete you need for your project, whether you're pouring a flat slab, filling a circular column, building stairs, or setting a curb. Just enter your measurements, and the tool will give you the volume, weight, and estimated cost of the concrete required.
The calculator supports five common shapes: flat surfaces like driveways and patios, circular slabs, tubes (hollow cylinders), curbs and gutters, and stairs. You can input dimensions in feet, inches, yards, centimeters, or meters, and switch between imperial and metric results with one click. It also lets you adjust the concrete density and price per unit so your estimate matches local material costs.
How to use our Concrete Calculator
Enter the dimensions of your concrete project and the calculator will tell you the total volume, weight of concrete needed, and estimated cost. Choose from five shape types: Flat, Circular, Tube, Curb, or Stairs.
Shape Type (Tab Selection): Pick the tab that matches your project. Choose "Flat" for slabs, patios, or driveways. Choose "Circular" for round pads or footings. Choose "Tube" for hollow columns or pipes. Choose "Curb" for curb and gutter work. Choose "Stairs" for concrete steps.
Width (Flat tab): Enter how wide your slab or surface is. You can pick your unit from feet, inches, yards, centimeters, or meters.
Length (Flat tab): Enter the length of the area you want to fill with concrete.
Thickness (Flat, Circular, and Tube tabs): Enter how thick or deep the concrete pour will be.
Diameter (Circular tab): Enter the full diameter of the circular area from one side to the other.
Outer Diameter (Tube tab): Enter the outer diameter of the tube or hollow column.
Inner Diameter (Tube tab): Enter the inner diameter of the tube. This is the hollow space inside.
Curb Depth (Curb tab): Enter the depth of the curb portion of your curb and gutter.
Gutter Width (Curb tab): Enter the width of the gutter that sits next to the curb.
Curb Height (Curb tab): Enter the height of the curb above the gutter surface.
Flag Thickness (Curb tab): Enter the thickness of the flat base layer beneath the curb and gutter.
Length (Curb tab): Enter the total length of the curb and gutter run.
Run (Stairs tab): Enter the horizontal depth of each individual step, also called the tread depth.
Rise (Stairs tab): Enter the vertical height of each individual step.
Width (Stairs tab): Enter how wide the staircase is from side to side.
Platform Depth (Stairs tab): Enter the depth of the landing or platform at the top of the stairs.
Number of Steps (Stairs tab): Enter how many steps your staircase will have.
Cost: Enter the price you expect to pay for concrete. You can set this per cubic foot, cubic yard, or cubic meter.
Density: Enter the density of the concrete mix you plan to use. The default is 133 lb/ft³, which is typical for standard concrete. You can switch between lb/ft³ and kg/m³.
Understanding Concrete Calculations for Construction Projects
Concrete is one of the most widely used building materials in the world. It is a mixture of cement, water, sand, and gravel that hardens into a strong, durable surface. Whether you are pouring a driveway, building a patio, setting fence posts, or constructing stairs, knowing how much concrete you need before you start is essential. Ordering too little means delays and weak joints between pours. Ordering too much means wasted money and material.
How Concrete Volume Is Calculated
The amount of concrete you need depends on the shape of your project. For flat slabs like sidewalks, patios, and driveways, you multiply the width, length, and thickness together to get the volume. For circular slabs like round pads or footings, the formula uses the radius (half the diameter) squared, multiplied by pi (3.14159) and the thickness. Tube or hollow cylinder shapes, often used for column footings, subtract the inner cylinder volume from the outer cylinder volume. Curb and gutter projects combine the flat gutter section with the raised curb section. Stairs are calculated step by step, adding the volume of each individual step together along with the platform.
Concrete Density and Weight
Standard concrete weighs about 133 pounds per cubic foot (roughly 2,130 kg per cubic meter). This is important to know because concrete is often sold by weight or by the cubic yard. One cubic yard of concrete equals 27 cubic feet and weighs approximately 3,600 pounds. Knowing the weight helps you figure out delivery needs and whether your subgrade or formwork can handle the load.
Estimating Cost
Concrete prices vary based on your location, the type of mix, and the quantity ordered. Ready-mix concrete delivered by truck is typically priced per cubic yard. Bagged concrete from a hardware store is priced per bag and is better for small projects. This calculator lets you enter a cost per cubic foot, cubic yard, or cubic meter so you can get an accurate estimate for your specific situation.
Tips for Ordering Concrete
Always order about 5% to 10% more concrete than your calculated amount. This extra material accounts for spillage, uneven ground, and slight changes in formwork dimensions. For any project larger than a couple of cubic yards, ready-mix delivery is usually cheaper and faster than mixing bags by hand. Make sure your forms are secure, your ground is compacted, and you have enough help on pour day — concrete does not wait for you to get ready.
Related Construction Material Calculators
If your project involves more than just concrete, you may also need to estimate other materials. Use our Asphalt Calculator if part of your project includes paving with asphalt rather than concrete. For decorative landscaping or drainage layers around your concrete work, our Pea Gravel Calculator and River Rock Calculator can help you determine the right quantities. If you're applying a protective or decorative coating to your finished concrete surface, our Epoxy Calculator will help you figure out how much epoxy you need for the job.