Introduction
A concrete footing is the base that holds up a building, wall, or post. It sits below the ground and spreads the weight of the structure into the soil. If the footing is too small or uses too little concrete, the structure can crack, shift, or sink over time. That is why knowing the right amount of concrete matters before you start any pour.
This Concrete Footing Calculator helps you figure out exactly how much concrete you need for your project. It works for four common footing types: continuous (strip) footings, rectangular pad footings, circular pad footings, and column or pier footings. Just enter your dimensions, pick your units, and the tool gives you the total volume in cubic yards, cubic feet, and cubic meters. It also tells you the estimated weight and the number of pre-mixed bags you need, with 10% added for waste.
You can also add a stem wall to strip footings or a bell footing to column piers for a more accurate estimate. For a deck, a fence, a retaining wall, or a house foundation, this calculator saves you time, cuts down on waste, and helps you order the right amount of concrete for the job.
How to Use Our Concrete Footing Calculator
Enter the shape, size, and number of your footings below. The calculator will tell you how much concrete you need in cubic yards, cubic feet, and cubic meters, plus how many bags of pre-mixed concrete to buy.
Footing Type: Pick the shape of your footing. Choose Continuous/Strip for long wall footings, Rectangular Pad for square or rectangle pads, Circular Pad for round pads, or Column/Pier for round posts that go into the ground.
Length: Enter the total length of your footing. This field shows for Strip and Rectangular Pad types. Pick your unit from the dropdown: inches, feet, yards, centimeters, or meters.
Width: Enter how wide your footing is. This field shows for Strip and Rectangular Pad types. Pick your unit from the dropdown.
Depth: Enter how deep or thick your footing is. This field shows for Strip, Rectangular Pad, and Circular Pad types. Pick your unit from the dropdown.
Diameter: Enter the width across your round footing or column. This field shows for Circular Pad and Column/Pier types. Pick your unit from the dropdown.
Height: Enter how tall your column or pier is from top to bottom. This field only shows for the Column/Pier type. Pick your unit from the dropdown.
Number of Footings: Enter how many identical footings you need to pour. The calculator multiplies the volume of one footing by this number.
Add Stem Wall: Turn this on if your strip footing has a stem wall on top. Enter the wall thickness and wall height. The stem wall volume is added to the base footing volume.
Add Bell Footing: Turn this on if your column pier has a flared bell at the bottom. Enter the bell diameter and bell height. The bell volume is added to the shaft volume.
Calculate: Press this button to get your results. The calculator shows total concrete volume, estimated weight, bags needed with 10 percent extra for waste, a volume breakdown table, and a bar chart comparing bag sizes.
Reset: Press this button to clear all fields and start over with the default values.
What Is a Concrete Footing?
A concrete footing is the base that sits under a wall, column, or pier and spreads the weight of a structure into the ground. Footings stop buildings from sinking, shifting, or cracking. They are one of the first things poured when construction begins.
Types of Concrete Footings
There are several common footing types used in construction. A continuous or strip footing runs along the length of a wall and is the most common type for houses and small buildings. A rectangular pad footing is a flat slab that supports a single post or column. A circular pad footing works the same way but uses a round shape. A column or pier footing is a tall cylinder of concrete that goes deep into the ground, often used for decks, porches, and fences. Some pier footings include a bell at the bottom, which is a wider cone shape that gives extra support in soft soil.
How This Calculator Works
This calculator finds the total volume of concrete you need for your footings. You pick your footing type, enter the dimensions, and choose how many footings you need. It gives you the volume in cubic yards, cubic feet, and cubic meters. It also shows the estimated weight and tells you how many pre-mixed bags to buy. The bag count includes an extra 10% for waste. The National Ready Mixed Concrete Association advises ordering 4% to 10% more than the volume worked out from plan dimensions, to cover waste, over-digging and other surprises.2
Why Footing Size Matters
Footings must be the right size to hold the load above them. If a footing is too small or too shallow, the structure can settle unevenly and crack. The International Residential Code bases footing width on the load-bearing value of the soil and sets a minimum of 12 inches wide and 6 inches thick.4 In cold climates, footings must also reach below the frost line so freezing soil does not push them upward.4 Always check your local building codes or talk to an engineer before you pour.
Tips for Pouring Concrete Footings
- Compact the soil at the bottom of your trench before you pour.3
- Use forms made of wood or metal to hold the concrete in shape.
- Add rebar or wire mesh if your building code requires it.
- Fill each footing in one continuous pour. Partial fills can leave cold joints.3
- Keep the concrete moist while it cures, typically for 3 to 7 days.5
- Order a little more concrete than the exact amount, since spills, uneven ground, and form bulges always use extra material.2