Concrete Calculator & Pour Planner

Estimate volume, materials, cost and weather readiness for your project.

What this calculator does

Free concrete calculator and pour planner for patios and slabs, driveways, sidewalks, garage floors, shed pads, strip footings, round piers (Sonotube), square columns, concrete steps, and curb & gutter. Enter your dimensions to get concrete volume, bag counts or ready-mix truck loads, base and reinforcement guidance, cost estimates, and a weather-readiness check for your pour date based on National Weather Service forecasts. Works in US imperial and metric units. All results are planning estimates — confirm quantities with your supplier and requirements with your local building department before ordering.

Choose a concrete calculator

Concrete slabPatios, shed pads, and general flatwork Concrete drivewayParking pads, aprons, and driveways SidewalkWalkways, paths, and crossings Garage slabGarage floors and workshops Shed padSmall equipment and storage pads Strip footingContinuous rectangular footings Sonotube / round pierDeck piers and round posts Concrete columnSquare and rectangular columns Concrete stepsStoops, landings, and stair flights Curb & gutterUniform drainage sections

Planning guides and methodology

Read the concrete planning guides by hub for project-specific measuring, thickness, base, joint, foundation, stair, and ordering context. Start with slabs and flatwork, driveways and walkways, or foundations, then use the methodology, sources, and limitations page plus the privacy and data use page to understand the formulas, boundaries, storage, and analytics behavior behind the results.

Concrete calculator FAQ

How do I calculate how much concrete I need?

Multiply length × width × thickness to get the volume, then convert to cubic yards (divide cubic feet by 27). Add about 5% extra for spillage and uneven subgrade. This calculator does the conversion automatically and applies a 5% waste factor to the recommended order volume.

How much concrete do I need for a 10×10 slab?

At 4 inches thick, a 10×10 ft slab needs 100 sq ft × 0.33 ft ≈ 33.3 cubic feet, or about 1.23 cubic yards. With a 5% waste factor, plan to order about 1.3 cubic yards.

How many bags of concrete equal one cubic yard?

Roughly 46 80-lb bags, 59 60-lb bags, or 91 40-lb bags. An 80 lb bag of concrete mix yields about 0.022 cubic yards (0.6 cubic feet) when mixed.

Should I order ready-mix concrete or mix bags?

As a rule of thumb, projects over about 1 cubic yard are usually better served by ready-mix delivery; below that, bagged concrete is practical. Many suppliers have a minimum load around 2 cubic yards and may add short-load fees, and a typical truck carries about 10 cubic yards. The calculator compares both options for your exact volume.

What temperature is best for pouring concrete?

This planner flags caution when the forecast falls below 40°F or above 90°F. Cold slows curing and risks freeze damage; heat speeds evaporation and can cause plastic shrinkage cracking. Warning-level severe weather and freezing lows are poor conditions, while watches and advisories prompt timing checks and protective planning when the actual pour-day forecast is otherwise moderate.

Does the calculator work in metric and imperial units?

Yes. You can switch between US imperial (feet and inches, cubic yards, lb bags) and metric (meters and centimeters, cubic meters, kg bags), and entered values convert automatically.