Types of Screw Heads & Drives: Phillips, Torx, Hex & More

You pulled an unknown screw from an appliance, a piece of furniture, or the back of a socket — and now you need to identify or replace it. The head shape tells you how it sits in the material. The drive type tells you what tool turns it. Both matter. Both are finite and learnable.

This guide covers every common combination you'll encounter in residential and light commercial work.

Part 1: Head Types (The Profile)

The head shape determines how the screw sits relative to the surface — flush, proud, or recessed. Here are the eight you'll encounter most often.

Flat (Countersunk)

The head tapers at 82° (imperial) or 90° (metric) to sit flush with — or below — the material surface when installed in a countersunk hole. This is the standard for wood joinery, flooring, and any application where a protruding head would snag or look wrong. Always pre-drill a countersink in hardwood or metal; driving without one cracks the surface.

Pan

Low-profile, slightly domed head with a flat or nearly-flat top. The most common head shape in machine screws and general fasteners. Pan heads provide a large bearing surface without requiring a countersunk hole. Used everywhere from electronics to appliances to light structural work.

Round

Fully domed head — taller than pan, purely functional appearance. Common in older hardware and electrical applications. Round heads have mostly been replaced by pan heads in modern manufacturing, but you'll still find them on legacy equipment and fixtures. If you're replacing one, a pan head is usually an acceptable substitute.

Truss (Mushroom)

Very wide, low dome — often twice the diameter of a pan head. The extra width distributes load over a large area, making truss heads ideal for thin sheet metal, aluminum, and anywhere you need to prevent pull-through without a washer. Common in HVAC ductwork, trailer manufacturing, and roofing clips.

Hex

Six-sided external hex head turned with an open-end or combination wrench. This is the standard bolt head — cap screws, structural bolts, lag screws. You won't confuse this with a screw head in the hand sense, but hex-head sheet metal screws exist for power-tool applications where a socket or nut driver is faster than a Phillips bit.

Socket Cap (Allen)

Cylindrical head with a recessed hex socket. Drives with an Allen key or hex bit. Socket caps are the go-to for machinery, bike components, furniture that must be assembled and disassembled (Allen key ships in the box), and anywhere tight clearance prevents a wrench. They provide much higher clamping force than equivalent pan-head machine screws.

Button

Low rounded head — somewhere between pan and round, with a socket cap's hex recess. Common on bicycles, motorcycles, and precision machinery where a tool-recessed, low-profile head is needed. Frequently combined with Torx drive on modern bike components.

Bugle

Similar to flat but with a curved underside instead of a straight taper. The curved flare compresses rather than splits the material as it drives — ideal for drywall and engineered wood products. Do not use bugle-head drywall screws in structural wood connections; the curved bearing surface reduces shear strength compared to flat heads.

Part 2: Drive Types (The Recess)

The drive type is what you see when you look straight down at the screw head. It determines which bit or tool turns the screw — and how much torque you can apply before stripping.

Phillips (#0–#4)

The most common drive type in North America. Four-armed cross (+) with angled flanks specifically designed to cam out (let the bit slip) at a set torque — a feature intended to protect lightweight 1930s power tools from stripping. In modern use, cam-out is the enemy: it strips the recess and leaves the driver rotating in a destroyed head.

The four sizes are: #0 (tiny electronics), #1 (small appliances), #2 (general-purpose — the most common), #3 (large lag-adjacent fasteners). When your driver spins without turning the screw, it's usually a size mismatch — most stripping is caused by using a #2 in a #1 hole.

Slotted

Single straight slot. The oldest drive type, dating to hand-tool work. Almost useless with power tools — the bit skips off sideways at torque, and alignment must be perfect. Still used in decorative trim screws, electrical cover plates, and heirloom furniture. If you see a slotted screw in a structural application, it was likely installed before the 1960s.

Torx (T6–T100)

Six-lobe star drive. Torx transfers torque through vertical walls rather than angled Phillips ramps — zero cam-out by design. This makes it the standard for modern structural screws (deck screws, drywall screws, self-drilling metal screws) and automotive fasteners.

The number refers to the across-lobe dimension: T6 fits tiny electronics screws, T25 is the standard deck screw size, T40+ is for large structural fasteners. If you work with power tools, a T20 and T25 bit handle 90% of modern residential fasteners.

Robertson (Square, #0–#3)

Square recess with a slight taper. The screw self-centers on the bit and stays on it without needing magnetic force — ideal for pocket-hole joinery and any overhead work where you need one-handed starts. Robertson is overwhelmingly common in Canada, in Kreg pocket-hole screws, and in IKEA's newer hardware.

Color coding: yellow = #0 (tiny), green = #1, red = #2 (most common), black = #3 (large). The taper means size matters — a #2 bit will not fit a #1 screw properly.

Hex / Allen (H1.5–H19)

Six-sided recessed socket, also called Allen or hex socket. Turned with an L-shaped Allen key or a hex bit. The hex drive is the standard for socket cap screws, set screws (grub screws), and most precision machinery fasteners. The recessed socket allows lower head profiles than external hex. Common sizes you'll need in a home shop: H2, H2.5, H3, H4, H5, H6 metric; 3/32", 1/8", 5/32", 3/16", 1/4" imperial.

Pozidriv (PZ0–PZ4)

Looks like Phillips but has four additional shallow ribs at 45° between the main arms. Developed by Philips and GKN to eliminate cam-out. Pozidriv is standard in European hardware — IKEA furniture, European appliances, German automobiles — but nearly invisible in North American retail. Using a Phillips driver in a Pozidriv screw will strip the recess; the bit sits too shallow and rocks.

Identification: look for small tick marks between the four arms of the cross. If you see them, it's Pozidriv. If the cross arms taper to points at the top with no markings, it's Phillips.

Choosing the Right Combination