01Opening vs Jaw Width
Jaw width is sideways room; jaw opening is the vertical gap between the jaws. A 6″ vise with 6-inch-wide jaws might open only 4-6 inches. Buyers who want to clamp a thick casting must shop by opening, not by the headline size number.
The difference matters enough that it runs through the whole size guide.
02Measure Your Largest Workpiece
First, measure the thickest thing you will clamp — a casting, a pipe section, a stack of angle iron. That dimension plus a little clearance is your minimum opening. Everything else the vise does is secondary to clearing your biggest part.
03Typical Openings by Class
Light-duty vises typically open 2-3″, medium-duty 4-6″, and heavy-duty 6-10″. The 6″ medium-duty bench vise opens enough for most workshop parts; an 8″ heavy-duty bench vise swallows assembled work and pipe that the smaller class cannot.
04When Max Opening Is the Whole Game
Pipe, castings, jigs and partially assembled work all need the jaws to clear the complete profile, not just a thin slice of it. Applications that do this constantly — fabrication, plumbing, maintenance — should weight opening higher than jaw width in how to choose a bench vise.
05Opening and Force Trade Hands
A wide opening is useless without the clamping force to hold the part, and both depend on body materials that keep the frame rigid under load. Check all three on the same model, not separately.
If your largest workpiece dictates a non-standard opening, the OEM team can specify one for your program.