Concrete Calculator
Determine the exact volume of concrete necessary for your upcoming pour in commercial cubic yards or standard ready-mix bags, factoring in a safe spillage margin.
Concrete Volume Estimator
Total Concrete Required
(36.67 Cubic Feet)
Pre-mixed
Pre-mixed
Note: Bag estimates include your 10% waste margin. Yields vary slightly by manufacturer. Check your bag's specific cubic foot yield.
Understanding Concrete Estimation
Ordering or mixing concrete correctly is one of the most critical steps in construction and DIY projects. Ordering too little can result in weak "cold joints" where old and new concrete fail to properly bond, while ordering too much is an expensive waste. This calculator aims to provide highly accurate yardage counts and bag estimates.
How Concrete is Measured
In the United States, commercial ready-mix concrete companies strictly sell their product by the Cubic Yard. For smaller DIY projects (like setting a fence post or a small garden slab), you will typically purchase pre-mixed concrete bags from hardware stores.
- 1 Cubic Yard is equivalent to 27 Cubic Feet.
- An 80-lb bag of concrete mix yields roughly 0.60 cubic feet. It takes exactly 45 bags of 80-lb concrete to equal 1 full cubic yard.
- A 60-lb bag yields roughly 0.45 cubic feet. It takes exactly 60 bags of 60-lb concrete to equal 1 cubic yard.
Why a Yield / Waste Margin is Critical
A concrete form is almost never a perfect geometric shape. The ground you pour onto is frequently uneven, the lumber forms bow slightly under pressure, and some concrete inevitably spills or gets stuck inside the mixer.
As an industry standard, contractors calculate the absolute mathematical volume and then add a 10% safety margin. For deeper, highly irregular holes like a fence post dug in rocky soil, a 15% to 20% margin is heavily recommended to avoid sudden mid-pour shortages.