What's inside
As an Amazon Associate I earn from qualifying purchases. This post may contain affiliate links at no extra cost to you.
The short answer
For a workbench on an uneven concrete floor, leveling feet are the better permanent solution. They are adjustable, compact, and less likely to shift when you push against the bench, run a planer, or clamp a workpiece. Shims are cheaper and perfectly adequate for a light assembly table, storage bench, or temporary setup.
The important distinction is not simply whether the bench is level. It is whether the support can resist movement after the bench is loaded and used. A shim can level a leg, but it does not automatically lock that leg in place. A threaded foot lets you make small corrections and spread the load through a broad, stable pad.
As an Amazon Associate we earn from qualifying purchases at no extra cost to you.
When shims are enough
Use shims when the floor is only slightly irregular, the bench is fairly light, and you do not need frequent adjustment. A simple workbench for hand tools, sanding, glue-ups, or light assembly may be completely stable with plastic or composite shims under its feet.
Plastic leveling shims are usually preferable to scraps of plywood. Wood absorbs moisture from concrete, compresses under concentrated loads, and can eventually rot or split. Composite shims also have a predictable thickness and are easy to trim with a utility knife or saw. For a bench leg carrying 100 to 200 pounds, a broad shim is much more reliable than a thin wedge or a stack of random scraps.
Shims become less attractive when you need more than about 1/4 inch of correction. A tall stack creates a gap that can let the leg slide sideways. It also concentrates force on a small edge. If you must build up more than that, use a solid platform or install a mechanical foot rather than stacking thin pieces.
Never use loose cardboard, folded paper, or several small coins as permanent leveling material. Those materials creep, crush, and can let a loaded bench rock. If you use shims, cut them so they are fully supported by the leg or foot and cannot protrude into a walking path.
Why leveling feet work better
Threaded leveling feet are best for benches with metal frames, heavy wooden bases, cabinets, or machinery. The threaded stud gives you continuous adjustment, while the foot’s pad spreads the load over the concrete. You can usually correct a floor variation of 1/2 inch or more without changing the bench frame.
For a typical workbench, look for feet with a 3/8-inch or 1/2-inch stud, a locknut, and a pad at least 1-1/2 inches in diameter. Heavier benches and machines benefit from larger pads, such as 2 to 2-1/2 inches. A small foot may be strong enough on paper but can punch into weak concrete, paint, or a dusty coating.
A locknut matters. Without one, vibration and repeated side loads can slowly turn the stud. That is especially likely on a bench holding a benchtop planer, grinder, or dust collector. If the frame accepts it, use adjustable leveling feet with locknuts rather than basic furniture glides.
Feet are not a cure for a weak or twisting bench. If the top flexes, the frame racks, or the legs are not square, leveling hardware will only make the defects easier to notice. Brace the base first, then level it.
Leveling feet versus shims
| Factor | Threaded leveling feet | Shims |
|---|---|---|
| Initial cost | Higher, especially for four heavy-duty feet | Very low |
| Adjustment | Fine, repeatable, and reversible | Coarse; may require lifting the bench |
| Resistance to movement | Good with locknuts and wide pads | Good only when tightly captured |
| Best use | Permanent benches, cabinets, and machinery | Light benches and temporary setups |
| Floor protection | Good with rubber or broad metal pads | Depends on the shim material |
How to level the bench correctly
Start by sweeping and vacuuming the floor. Concrete dust under a foot can act like a bearing and allow movement. Check whether the slab has a high spot, a low spot, or a general slope. A four-foot level is useful, but a shorter level can give misleading results if the bench top itself is not straight.
Set the bench in its final position and check the top from front to back and side to side. Do not assume the floor is the only problem. Check the legs and frame, then place a level across the working surface. Adjust the lowest corner first, making small changes until the top is level without rocking.
With threaded feet, turn the feet by hand or with the supplied wrench, then tighten each locknut against the frame. Recheck the level after loading the bench. A cabinet full of hardware can add several hundred pounds and slightly compress rubber pads or reveal a weak leg.
With shims, lift one corner only as much as needed and slide in a single full-width shim. Tap it in until the bench stops rocking, then check the top again. If the shim can be pushed out by hand, it is not captured well enough. For a wooden bench, fasten the shim to the underside of the leg with a screw, or use a rubber furniture pad over the shim to increase friction.
Special cases and buying tips
For a bench that houses a table saw, planer, or router table, prioritize stability over the lowest price. Vibration can move a light bench even when it is technically level. Consider heavy-duty machine leveling feet with wide pads, and keep the center of gravity low. If the machine must be moved often, locking casters combined with leveling pads may be more practical than ordinary feet.
Rubber-padded feet help on painted or sealed concrete, but soft rubber can compress under a heavy load. Steel feet are durable but may slide or mark a finished floor. For a wooden workbench, threaded insert leveling feet for a workbench provide a clean retrofit. Install the inserts square to the leg and leave enough wood around them; thin end grain can split.
Choose shims when the bench costs little, the correction is small, and moving it later is likely. Choose leveling feet when the bench is heavy, permanent, vibration-prone, or expected to stay accurate after years of use. In either case, level the bench after installing storage, dust-collection hoses, and other equipment. A stable, non-rocking work surface is more important than achieving a perfect bubble if the bench can still slide across the floor.