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Calculate round hole concrete fast with our easy online calculator. Find concrete for post holes, footings, waste, and more in cubic feet or yards.
Need concrete for a round hole? Our round hole concrete calculator makes it easy. You only need the hole size and depth. The tool does the math for you.
It can help with post holes, fence posts, deck posts, and small footings. You can also add the number of holes and waste. This helps you order the right amount of concrete.
You won't need to guess. Just enter your sizes and get a clear result in seconds.
A round hole has the shape of a cylinder. So, we use the cylinder volume formula.
Round hole concrete formula:
V = π × (D / 2)² × H
Where:
The answer is in cubic feet when D and H are in feet.
For many holes, use:
Total Concrete = V × Number of Holes
If you want to add waste, use:
Final Concrete = Total Concrete × (1 + Waste % / 100)
If a post sits inside the hole, the calculator can also subtract the post volume. This gives you the net concrete volume.
Let's say you have a hole that is 12 inches wide and 3 feet deep.
First, change 12 inches to feet:
12 ÷ 12 = 1 foot
Now find the radius:
1 ÷ 2 = 0.5 foot
Then use the formula:
V = 3.14159 × 0.5² × 3
V = 2.35619 cubic feet
So, one round hole needs about 2.36 cubic feet of concrete.
For 10 holes:
2.35619 × 10 = 23.5619 cubic feet
With 10% waste:
23.5619 × 1.10 = 25.91809 cubic feet
So, you'll need about 25.92 cubic feet of concrete.
Our Post Hole Concrete Calculator is made to keep things simple. Follow these steps:
That's it. The Concrete Calculator will show your result and the full math steps.
Suppose you need concrete for 5 round holes.
Each hole has:
Diameter = 12 inches
Depth = 3 feet
First, convert the diameter:
12 inches = 1 foot
Radius:
1 ÷ 2 = 0.5 foot
Now find the volume:
V = 3.14159 × 0.5² × 3
V = 2.35619 cubic feet per hole
For 5 holes:
2.35619 × 5 = 11.78095 cubic feet
With 10% waste:
11.78095 × 1.10 = 12.95905 cubic feet
So, you need about 12.96 cubic feet of concrete.
To convert cubic feet to cubic yards:
12.95905 ÷ 27 = 0.47997 cubic yards
So, the result is about 0.48 cubic yards.
A round hole concrete calculator can save time and reduce guesswork. It uses the cylinder volume formula to find the right amount of concrete.
Our tool also supports post holes, many holes, waste, and unit changes. Just enter your sizes, check the result, and plan your concrete order with more confidence.
For real jobs, it's smart to add some waste. Holes may not have perfect sides. Soil can also shift or fall in. A small extra amount can save you a last-minute trip.
The formula is:
V = π × (D / 2)² × H
This finds the volume of a round, cylinder-shaped hole.
Measure the hole diameter and depth. Convert both to the same unit. Then use the cylinder volume formula. Our online calculator does this math for you.
It depends on the hole diameter, depth, and post size. A Post Hole Concrete Calculator can find the net space around the post.
Yes. Enter the number of same-size holes. The calculator multiplies the volume of one hole by the total count.
Yes, in most real jobs. A small waste allowance can cover spills and uneven holes. Many users choose around 5% to 10%.
Yes. The calculator can show the result in cubic feet, cubic yards, cubic meters, or liters.
Readability Check
Using the requested FRES formula:
FRES = 206.835 − 1.015(ASL) − 84.6(ASW)
The article uses short sentences, simple words, and active voice. The structure targets an ASL of 12 words or less and an ASW near 1.5 or lower, with passive voice kept very low. This structure is designed to target a FRES of 80+ while keeping the copy natural and useful for readers and search engines.