How to use it
- Enter the hole diameter in inches.
- Enter the depth in feet.
- Enter the number of holes.
- Read the cubic yards, cubic feet and bag count.
What it does – The calculator takes the diameter of your post hole, its depth, and how many holes you’re digging, then instantly shows the total volume in cubic feet, converts that to cubic yards, and tells you how many standard 80‑lb bags of concrete you’ll need.
Why it matters – Ordering too little concrete stops work; ordering too much wastes money and space. Seeing all three units lets you compare to supplier quotes, plan deliveries, and keep a waste buffer.
How to read the results – Cubic feet is the raw volume of all holes combined. Divide by 27 to get cubic yards, the unit many suppliers use. Divide cubic feet by 0.6 to see the exact number of 80‑lb bags; round up to the next whole bag for ordering.
Pro tips
- Add 5‑10% extra bags for spillage and compaction.
- Round up the bag count; you can’t order a fraction of a bag.
- Check supplier’s bag yield; some mixes differ slightly from 0.6 ft³.
- Measure diameter and depth at the deepest point for accurate volume.
Real-life examples
- Planning a new fence and need concrete for 8 post holes.
- Installing a deck and must order mix for 12 foot‑deep footings.
- Replacing damaged utility poles and calculating material for multiple holes.
Case study
Sam needed concrete for 6 10‑inch, 3‑ft deep post holes. Using the calculator he saw he required 9.5 ft³ → 0.35 yd³ → 16 bags. He ordered 16 bags, avoided a second delivery, and finished the fence on schedule.