Every wobbly table has one of two causes: the legs are uneven, or the floor is uneven. Thirty seconds of diagnosis tells you which, and both have permanent fixes that beat the folded napkin.
Diagnose It First
Move the table a foot in any direction. If the wobble follows the table, the legs are uneven. If the wobble changes or disappears, the floor is the problem (and the napkin trick will fail the next time the table moves).
Fix 1: Adjustable Leveling Feet (the permanent fix for both causes)
Adjustable rubber leveling feet thread into the leg and screw in or out to dial each corner to the floor — the same hardware machine shops use on workbenches. Drill a hole in each leg bottom, tap or insert a threaded insert, thread in the foot, and level by hand. Our adjustable feet & leveling legs list every thread size, and the rubber pad grips the floor and protects it at the same time. For heavy benches and machinery, see larger equipment feet.
Fix 2: Rubber Caps to Shim a Short Leg
For a slightly short leg on a table you don't want to drill, a thick-walled rubber leg cap on the short leg (or thinner caps on the other three) levels the table and stops floor scratches at the same time. Measure the leg diameter and match the cap's inside diameter.
Fix 3: Screw-On Rubber Feet for Slide and Chatter
If the table is level but skates or chatters on hard floors, the problem is hard feet on a hard surface. Screw-on rubber bumper feet add grip and absorb the chatter — pick a diameter close to the leg base and mount with one screw per foot.
Fix 4: Fix the Joint, Not the Foot
If the top itself racks side-to-side while the feet stay planted, the wobble is a loose leg joint — tighten the corner bolts or hanger bolts, and re-glue a loose wooden joint. No foot hardware fixes a loose joint.
Chairs wobbling too? The same diagnosis applies — see the chair leg cap size chart. Equipment vibrating rather than wobbling? That's an isolation job: choose a vibration isolator mount.