How much concrete is needed for a footer that is 12 inch by 3 foot deep?

To calculate the volume of concrete needed for a footer that is 12 inches wide and 3 feet deep, first convert the dimensions to feet. The width is 1 foot (12 inches) and the depth is already 3 feet. The volume is calculated using the formula: volume = width × length × depth. Assuming the length is 1 foot, the volume would be 1 ft × 1 ft × 3 ft = 3 cubic feet of concrete needed.