What Is the Concrete Footing Calculator?
The Concrete Footing Calculator is a free online tool designed for contractors and DIY builders who need quick, accurate calculations in the construction and building space. By entering your footing shape, diameter, width, you get instant results including total cubic yards, total cubic feet. No formulas to memorize, no spreadsheets to build — just enter your numbers and get the answer in seconds. Whether you're a beginner or experienced professional, this calculator saves you time and eliminates guesswork.
Why This Calculation Matters
Getting total cubic yards right can make the difference between success and costly mistakes. In construction and building, small errors compound quickly. Manual calculations are error-prone and time-consuming, especially under pressure. This calculator applies proven formulas used by contractors and DIY builders worldwide, giving you confidence that your numbers are correct. Use it to plan your projects with precision and avoid common pitfalls that trip up beginners.
When Should You Use This Calculator?
This tool is most useful when you know your footing shape and need to find the right total cubic yards. It's also great for quick estimates before committing to a decision, and to double-check manual calculations or professional quotes, and when comparing different scenarios side by side. Bookmark this page and come back whenever you need a fast, reliable answer — the calculator is always free and requires no signup.
Concrete Footing Calculator
Quick Presets
Round Footing Concrete Volume
Cubic feet per footing by diameter and depth.
| Diameter | 36" Deep | 42" Deep | 48" Deep |
|---|---|---|---|
| 8" | 0.12 | 0.14 | 0.17 |
| 10" | 0.18 | 0.21 | 0.27 |
| 12" | 0.26 | 0.33 | 0.39 |
| 14" | 0.36 | 0.45 | 0.53 |
| 16" | 0.47 | 0.58 | 0.70 |
| 18" | 0.59 | 0.74 | 0.88 |
| 24" | 1.05 | 1.31 | 1.57 |
How to Use This Calculator
- Enter Your Footing Shape: Start by entering your footing shape — this is the primary input for the calculation.
- Fill In Additional Details: Complete the remaining fields: diameter, width, length, depth, number of footings, price per cubic yard. Each value refines the calculation for greater accuracy.
- Click Calculate: Hit the Calculate button to run the numbers. Results appear instantly below.
- Review Your Results: Check your total cubic yards, total cubic feet. Use these figures to inform your next decision or compare against alternative scenarios.
How It Works
Footings support structures by distributing weight into the ground. Calculating the right amount of concrete depends on the footing shape, size, and quantity.
The basic rule:
- Round footings (piers): π × (diameter/2)² × depth. Convert all measurements to feet first
- Rectangular footings: length × width × depth. Typical wall footings are twice the wall width
- Footings must extend below the frost line — check your local building code for the required depth
For deck piers and post footings, round Sonotube forms are most common. For wall footings and strip footings, rectangular forms are standard. Always add 10% extra concrete for waste and spillage.
Tips & Considerations
- Double-check your footing shape before calculating — even small input errors can significantly change your results.
- Run the calculator with different values to compare scenarios and find the optimal approach for your situation.
- Pay attention to both total cubic yards and total cubic feet — they work together to give you the full picture.
- Bookmark this page for quick access next time you need to plan your projects.
- If you're unsure about your price per cubic yard, start with a conservative estimate and adjust from there.
Frequently Asked Questions
How deep should footings be?
Footings must extend below the frost line, which ranges from 12 inches in southern states to 48+ inches in northern states. Check your local building code. Typical depths: deck footings 36-48 inches, fence posts 24-36 inches, house footings per engineer specs.
What size footing do I need for a deck?
Most deck footings use 12-inch diameter Sonotube forms set 42 inches deep. For heavy loads or tall decks, 16-inch or 18-inch diameter may be required. Check your local building code — most require a permit and specify minimum footing sizes for decks.
How much concrete for a fence post hole?
A typical fence post hole (8 inches diameter, 36 inches deep) uses about 0.3 cubic feet of concrete — roughly one 50-lb bag per post. For a 6-foot privacy fence, you need a post every 6-8 feet, so a 100-foot fence needs about 13-17 posts.
Can I mix my own concrete for footings?
For a few small footings, bagged concrete mix is practical. For larger jobs (over 1 cubic yard), ordering ready-mix is faster, stronger, and often cheaper. One 80-lb bag yields about 0.6 cubic feet of concrete.
Do footings need rebar?
Most building codes require at least 2 pieces of #4 rebar in wall footings and 1 piece of rebar extending up from pier footings into the post bracket. Rebar prevents cracking and ties the footing to the structure above. Always follow your local code.
What is the difference between a footing and a pier?
A footing is a wider concrete base that spreads the load over more soil — typically used under walls and foundations. A pier is a round or square column of concrete (often formed with a Sonotube) that carries point loads, like deck posts. Many structures use both: a footing at the bottom with a pier extending up.