A hammer drill is built for one job that regular drills can’t do well: drilling into hard, brittle materials like concrete, brick, and stone. It combines the spinning motion of a standard drill with thousands of rapid forward impacts per second, essentially punching the bit into the material while it rotates. If you’ve ever tried to bore a hole in a concrete wall with a regular drill and watched the bit spin uselessly, a hammer drill is the tool that solves that problem.
How a Hammer Drill Works
Inside the drill, a pair of ridged discs (called cams) mesh and separate as the chuck spins. Every time they separate, the chuck jolts forward slightly, then snaps back. This happens incredibly fast. Modern cordless hammer drills deliver roughly 30,000 to 39,000 of these tiny blows per minute while spinning at 2,000 to 2,600 RPM. The combination of rotation and rapid percussion pulverizes hard material grain by grain, where rotation alone would just polish the surface.
Most hammer drills have a switch or mode selector that lets you turn the hammering action on or off. With hammer mode off, the tool works as a normal drill for wood, metal, and plastic. This dual functionality is what makes it one of the most versatile power tools you can own.
The Jobs That Need a Hammer Drill
The core use case is drilling holes in masonry for anchors, screws, or bolts. Practically, that covers a wide range of common projects:
- Mounting a TV bracket to a concrete or brick wall. You drill holes, insert plastic anchors or sleeve anchors, and drive screws into them. Without the hammering action, you simply can’t get a clean hole in these materials.
- Installing concrete screws (like Tapcon fasteners). These require a precisely sized pilot hole drilled with a carbide-tipped masonry bit in a hammer drill. They’re the standard fastener for attaching lumber, brackets, and electrical boxes to concrete and block walls.
- Securing a ledger board to a foundation. Deck construction often requires bolting a horizontal board directly to a concrete foundation wall.
- Fastening bottom plates to a concrete slab. When framing a wall on a basement floor or garage slab, you need to anchor the bottom plate to the concrete.
- Running wiring or plumbing through masonry. Drilling through a brick exterior wall for a dryer vent, cable pass-through, or hose bib requires a hammer drill.
- Installing shelving, handrails, or grab bars in brick or block. Any fixture that carries weight needs a solid mechanical anchor in masonry, which starts with a properly drilled hole.
Essentially, any time you need to attach something to concrete, brick, cinder block, or morite, a hammer drill is the right tool.
When NOT to Use Hammer Mode
The hammering action that makes this tool effective on masonry will damage softer or more brittle materials. Drilling into tile or glass with hammer mode on will crack or shatter them. Wood will splinter and tear rather than cut cleanly. Metal doesn’t benefit from the impact at all, and the vibration just wears out bits faster and produces sloppy holes.
Switch hammer mode off for wood, metal, plastic, drywall, and ceramic tile. If your hammer drill doubles as your everyday drill (which is the whole idea for most homeowners), just remember that the hammer function is exclusively for masonry.
Hammer Drill vs. Rotary Hammer
These tools overlap in purpose but differ significantly in power. A standard hammer drill uses those cam-action discs to create a relatively light percussive force, delivering around 2 to 5 joules of impact energy. That’s plenty for holes up to about 1 inch in diameter in brick, mortar, and concrete block.
A rotary hammer uses a piston mechanism (similar in concept to a pneumatic jackhammer) and delivers 6 to 12 joules of impact energy. It’s designed for solid poured concrete and stone, for larger-diameter holes, and for all-day drilling on a job site. It also typically has a “hammer only” mode that lets it function as a light demolition tool with a chisel bit.
For most homeowners and general DIYers, a hammer drill handles everything you’ll encounter. If you’re drilling dozens of holes in a poured concrete foundation or need holes larger than an inch in diameter, that’s when you’d step up to a rotary hammer.
Bits and Accessories
A hammer drill is only as good as the bit you put in it. Standard twist bits designed for wood or metal will dull almost instantly in concrete. You need carbide-tipped masonry bits, which have a wider, chisel-shaped tip made from tungsten carbide that can withstand the repeated impact.
Most consumer hammer drills use a standard three-jaw chuck that accepts straight-shank or 3-flat shank bits, the same bits you’d find at any hardware store. Rotary hammers use a different system called SDS-Plus or SDS-Max, where the bit clicks into a slotted holder rather than being tightened in a chuck. SDS bits can slide slightly forward and back, which lets the hammering mechanism work more efficiently. If you’re shopping for bits, check which shank style your drill accepts before buying.
For concrete screws specifically, the screw manufacturer specifies the exact bit diameter you need. Using the wrong size will either make the screw too loose to hold or too tight to drive without snapping. This is one area where precision matters, so follow the packaging.
Dust and Noise Protection
Drilling into concrete and brick creates fine silica dust, which is a serious respiratory hazard with repeated exposure. OSHA regulates crystalline silica exposure on construction sites, setting a permissible limit of 25 micrograms per cubic meter of air over an eight-hour period. You’re unlikely to hit that threshold drilling a few holes for a shelf bracket, but it’s still smart to wear a dust mask or respirator rated for fine particles (N95 or better) whenever you drill into masonry.
Hammer drills are also loud, particularly when working on concrete. Hearing protection is worth grabbing along with safety glasses. The vibration from extended use can also fatigue your hands and wrists, so take breaks if you’re drilling more than a few holes at a time.
What Speed Settings to Use
Counter to what you might expect, faster isn’t always better with a hammer drill. Pro Tool Reviews tested several leading cordless hammer drills and found that the model with the fastest concrete drilling times had one of the lower blow-per-minute ratings (32,000 BPM) but the highest rotation speed (2,500 RPM). The combination of rotation speed and impact rate matters more than either number alone.
In practice, start at a lower speed to establish the hole without the bit wandering across the surface, then increase speed once you have a solid starting point. If you hit rebar or an especially hard aggregate in the concrete, back off the pressure and let the tool do the work. Forcing it just overheats the bit and slows you down.