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Match the bit to the anchor
For plastic masonry anchors, the right bit is usually the one specified on the anchor package—not the one that matches the screw. The anchor expands inside the hole, so a hole that is too large may let it spin or pull out; one that is too small can split the anchor or make installation difficult. Common plug sizes call for masonry bits around 1/4, 5/16, or 3/8 inch, but check the instructions for the exact anchor you bought.
Measure the bit’s carbide tip, not just its shank. Some masonry bits have a wider cutting head, and that head determines the hole size. If the packaging is missing, test the fit in a scrap block or an inconspicuous spot: the anchor should enter with firm pressure and sit flush, not drop in loosely or require forceful hammering.
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Choose a bit for the material
For ordinary brick, concrete block, and poured concrete, a carbide-tipped masonry bit is the standard choice. A basic two-cutter bit is inexpensive and adequate for a small number of holes in brick or block. For harder concrete or repeated drilling, a bit with a four-cutter carbide head is less prone to catching and generally holds up better. The trade-off is cost: for a few small holes in soft brick, the upgrade may not matter.
For regular home repairs, a carbide-tipped masonry bit set gives you useful sizes without buying each bit separately. Check that the sizes match your anchors and that the set fits your drill chuck. Avoid using a wood or metal bit on masonry; it may barely cut, overheat, or become damaged.
Bit style also has to match the drill. A straight-shank masonry bit fits a standard three-jaw chuck. SDS-Plus bits fit SDS rotary hammers, not ordinary drill chucks. Don’t buy an SDS bit unless your tool accepts it, and don’t clamp a round-shank bit in an SDS holder unless the tool maker specifically supports that arrangement.
Hammer mode and drill choice
A hammer drill combines rotation with a rapid forward tapping action. On many models, you can switch that action off for wood and metal. Use hammer mode for masonry when your drill manual recommends it; use rotation-only mode for tile and other brittle surfaces. A standard cordless drill can make holes in soft brick with a sharp masonry bit, but it will usually be slower in concrete. For many anchors in hard concrete, a rotary hammer is faster and easier on your hands.
Set the drill to low or medium speed and keep steady pressure on the bit. High speed and excessive force can overheat the carbide tip or polish the hole instead of cutting it. If your drill has a clutch, set it for drilling rather than screw driving. Keep the bit straight: a hole angled off course can leave the anchor close to an edge, weaken the fixing, or prevent a bracket from sitting flat.
For a larger batch of holes in concrete, compare your current tool with a cordless SDS-Plus rotary hammer. It is unnecessary for a couple of anchors in soft brick, but it can save time where a regular hammer drill struggles.
Bit options at a glance
| Bit or tool | Best use | Trade-off |
|---|---|---|
| Basic two-cutter carbide masonry bit | A few holes in brick or block | Often slower to wear-resistant concrete; can wander if you rush |
| Four-cutter carbide masonry bit | Repeated holes or harder concrete | Costs more; unnecessary for light-duty work in soft masonry |
| SDS-Plus bit in a rotary hammer | Many holes in concrete | Requires an SDS-Plus tool and is not for a standard chuck |
Drill the hole to the right depth
Check for wiring and plumbing before drilling, especially near outlets, taps, and switches. Mark the anchor’s required depth on the bit with a piece of tape, or use the drill’s depth stop. The hole should be at least as deep as the anchor, with a little extra room—about 1/8 inch is a practical allowance for dust—unless the anchor instructions specify otherwise. Don’t drill unnecessarily deep near an edge or where hidden services may be present.
Start slowly with the bit held square to the wall. Once it has made a shallow guide, increase speed and engage hammer action if appropriate. Pause now and then to withdraw the bit and clear dust from the hole. Packed dust can stop the anchor short and make it seem as though the hole is undersized. A bulb blower or vacuum is safer for cleanup than blowing dust toward your face; wear eye protection and a suitable dust mask.
If the bit gets hot, stop and let it cool. Don’t quench a hot carbide bit in water: sudden temperature change can damage it. A bit that has gone blunt may squeal, smoke, or take much longer than usual to advance. Replace it rather than forcing the drill, which can overheat the tool and leave a poor hole.
Install and check the anchor
After clearing the dust, push the plastic anchor in by hand. If needed, tap it gently with a hammer until it sits flush. If it will not go in with moderate tapping, stop and check the hole diameter, depth, and debris. Driving it hard can buckle or split the plug. If it slips in loosely or spins when you tighten the screw, the hole may be too large, damaged, or drilled in crumbly masonry. Move to a fresh location and use an anchor suited to the material; a larger screw does not reliably fix an oversized hole.
Use a sharp individual carbide masonry bit when you need one exact size rather than a full set. For a handful of anchors in sound brick, a basic bit in the specified diameter is usually the economical choice. Spend more on a tougher bit or rotary hammer when the masonry is hard, the hole count is high, or the cheaper setup is clearly struggling.