How to use it
- Enter length in feet.
- Enter width in feet.
- Enter thickness in inches.
- Read cubic yards, cubic feet, and bag count.
What it does – The calculator turns the three dimensions of a footing into three useful outputs: total cubic feet, cubic yards, and the number of 80‑lb bags needed. Why it matters – Knowing the exact volume prevents ordering too little concrete (causing delays) or too much (wasting money). How to read the results – Cubic feet is the raw volume; divide by 27 to get cubic yards, the standard delivery unit. Multiply cubic feet by 1.667 (the inverse of 0.6 cf per bag) to see how many bags you’ll order. Round up to the next whole bag and add a small waste allowance for spillage or uneven sub‑grade. You can reuse the same calculation for multiple footings by summing each result, making it easy to plan a full‑size patio or garage foundation.
Pro tips
- Add 5‑10% extra volume for waste and spillage.
- Round up bag count to the next whole bag; you can’t order a fraction.
- Order bags in multiples that match the supplier’s delivery minimum.
- Double‑check thickness conversion from inches to feet before entering.
Real-life examples
- A homeowner sizing footings for a new deck.
- A contractor estimating concrete for a shed foundation.
- A DIY enthusiast planning a garden retaining wall footings.
Case study
Mike needed footings for a 12 ft × 8 ft patio slab 6 in thick. Using the calculator he saw he required 2.0 cubic yards, 108 cubic feet, and 180 bags. He ordered 190 bags, avoided a costly short‑fall, and completed the patio on schedule.