Rhode Island Journeyman Plumber Practice Exam 2026 - Free Journeyman Plumber Practice Questions and Study Guide

One cubic foot contains 7.48 gallons of water. This conversion is based on the known relationship between volume measurements in the U.S. customary system. To understand this, it's helpful to recognize that a cubic foot is a three-dimensional measurement indicating the volume occupied by a cube with each side measuring one foot.

Since 1 foot is equivalent to 12 inches, when you calculate the volume in cubic inches (12 inches x 12 inches x 12 inches), you find there are 1,728 cubic inches in one cubic foot. The conversion factor is that there are 231 cubic inches in a gallon. Dividing the total cubic inches in a cubic foot (1,728) by the cubic inches in a gallon (231) yields approximately 7.48 gallons.

This is an important fact for plumbing and various engineering calculations, as understanding the relationship between volume and liquid measurements is vital in the design and installation of water systems.