Get the countersink depth needed for a flat-head screw to sit flush, plus the drill point depth beneath it. Enter head diameter, head thickness and countersink angle.
Let our engineers find the right factory for your specs. 100% Quality Guaranteed.
Request a Proposal →A countersink creates a conical recess for a flat-head fastener to sit flush with or below the surface. The depth depends on the head diameter of the screw and the countersink angle (typically 82 deg for inch fasteners, 90 deg for metric).
Historical convention. ANSI B18.6.3 specifies 82 deg for inch flat-head screws. ISO 7721 specifies 90 deg for metric. The difference is small enough that many shops use a 90 deg countersink for both -- it slightly undercuts the head but is functionally fine for most applications.
Use a countersink gauge (dial depth gauge with a conical tip) or a Deltronic pin method: place a known-diameter pin in the countersink and measure the height above the surface. Calculate depth from the pin diameter and protrusion. Alternatively, use the screw itself as a go/no-go gauge -- it should sit flush to 0.1 mm below the surface.
Yes, for small screw sizes (under M5 or #10) and light-duty applications. The 60 deg angle of a centre drill differs from standard countersink angles, so the screw head won't seat perfectly. For production, use the correct-angle dedicated countersink tool.
Enter the countersink diameter (screw head diameter) and the countersink angle. The calculator gives the depth to feed the countersink tool. Add 0.05-0.1 mm for flush seating; add 0.2-0.3 mm for below-flush (for filling or covering).
Continue with closely related tools from the machining calculator library.
Use the calculator freely. If the result points to a tooling or process problem, we can source the exact carbide tooling you need from vetted factories in China. Compare factory-direct pricing.
Before you commit to a spec, it helps to know what the market pays for it. These are real, publicly listed factory prices — not a quotation, and not a guess.
We source the tool families below direct from vetted Chinese factories, matched to the material and tolerance you just worked out. Every batch ships with its material certificate and dimensional record.
Explore more precision machining tools and calculators
CUTTING COUNTERSINKS? Countersink tooling is usually custom, which means the inquiry has to be right the first time. See how to brief a Chinese tool maker.
Tell us the part material, lot size, and target price. We’ll match a verified China factory and return a quotation within 48 hours.