How to Install Hollow Wall Anchors | The Right Way in 5 Steps

Installing hollow wall anchors requires drilling the correct-size hole, inserting the anchor flush, and then setting it so it expands behind the drywall.

Hanging shelves, towel bars, or a heavy mirror on drywall almost always ends at the same question: how to install hollow wall anchors so the thing actually stays put. The honest answer is that the method depends on the anchor type you’re holding — a toggle, a molly, or a self-drilling style each set differently. The good news is the core process is the same across all of them, and once you understand the sequence, you can handle any anchor on the shelf.

What You Need Before You Start

Gather the right tools first so you don’t break momentum mid-job. Most hollow wall anchor installations require a drill, the correctly sized drill bit, a screwdriver or drill driver, and a hammer or mallet. Some anchor styles, particularly certain molly bolts, also need a setting tool to expand the anchor properly behind the wall.

The single most important item is the drill bit. Match the bit size to the anchor’s specification — using one that’s too small makes the anchor impossible to insert, and one that’s too large destroys the grip it needs in the drywall. Also check the wall for hidden electrical wiring and plumbing before drilling. A stud finder with a wire-detection mode is the standard way to do this, and it’s a step that’s far cheaper than repairing a punctured pipe.

Because you’ll be working with metal and drywall dust, wear safety glasses. The debris falls straight into your eyes if you’re looking up at the anchor.

How to Install Hollow Wall Anchors: The Core Method

Start by marking your location and confirming the wall cavity is clear. Then drill your pilot hole using the specified bit size. For toggle bolts and steel hollow wall anchors, that pilot hole needs to be larger than for some other types, so check the packaging guidance before you drill.

Insert the anchor into the hole and tap it flush with a hammer or rubber mallet until the head sits fully against the wall surface. For toggles, this means pushing the wings through the hole and pulling them snug against the back of the drywall, then removing the plastic strap or setting aid before tightening the screw. For molly-style anchors, you insert the anchor first, then tighten the screw so the back side crimps and expands against the inside surface of the wallboard

Once the anchor is set, remove or back out the screw if the instructions call for it, then position your fixture and reinsert the screw to fasten the item. The final tightening should feel firm, not forced. Overtightening is the most common failure point — it strips the screw, damages the drywall, or both.

For self-drilling anchors, the process is even simpler: tap the anchor until the gripper prongs embed in the board, then press firmly on the screw and turn clockwise until the barrel crimps against the inside of the wall.

Comparison of Common Hollow Wall Anchor Types

All hollow wall anchors work on the same principle — spreading load across the back of the drywall — but each type has a different installation profile. The table below breaks down the key differences.

Note that these load figures are broad ballpark ranges, not universal specifications. There is no single load rating that applies to all hollow wall anchors — the actual holding strength depends on the wallboard thickness, the anchor’s size, and how well it was set. When in doubt, choose a larger anchor or add a second one to spread the load.

Common Mistakes and How to Avoid Them

Most hollow wall anchor failures trace back to one of four errors. The first is using the wrong hole size — recheck the anchor packaging for the drill bit spec before you start. The second is failing to set the anchor flush before tightening, which prevents the teeth or prongs from biting into the wallboard correctly.

The third mistake is overtightening the screw, which strips the anchor or crushes the drywall. The fourth is skipping the wiring and plumbing check entirely — always verify what’s behind the wall before drilling.

A less obvious error happens with molly anchors: not leaving the correct screw gap for the setting tool. The instructions for some hollow-wall styles require backing the screw out 2–3 turns so the tool can fit behind the screw head to squeeze and expand the anchor. If you skip this, the anchor won’t expand fully and your fixture will be hanging on a loose grip.

One final tip: for lighter fixtures like towel bars, a self-drilling anchor is usually enough. But for heavier items like a large mirror or a floating shelf, step up to a toggle bolt or a steel hollow wall anchor. If you’re securing a hollow interior door specifically, our tested roundup of the best anchor for hollow door use cases explains which styles handle that thinner, more fragile surface best.

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