When you build a wall, the studs should be spaced equidistant from each other. Here’s why the standard is 16 inches "on center", and an easy way to mark them.
"16 inches on center" means the center of each 2×4 wall stud is 16 inches apart from the next one. This standard is necessary because building materials are designed to fit that space. For example, insulation and medicine cabinets will only fit into a 16 inch layout. This uniform distance also makes it easier to locate wall studs when hanging mirrors or cabinets.
You need a framing square, measuring tape and pencil to measure and mark your distances accurately.
Start by aligning your top and bottom plate ends flush together and measure 15 1/4 inches to side of first stud placement. Each corresponding measurement should be 3/4 of an inch shy of stud marks on your tape measure. This will give you studs that are on 16 inch center layouts. Check out the video above to see this process in action.
How to Frame a Wall 16 Inch on Center | Home Remodel Workshop (YouTube)
via Lifehacker
The Easy Way to Frame a Wall 16 Inches on Center