Design a step drill. Enter the final hole diameter, the increment per step and the number of steps to get the full list of step diameters and the length of each step.
Let our engineers find the right factory for your specs. 100% Quality Guaranteed.
Request a Proposal →Published starting values are not measurements. They are recommendations, and they differ because each manufacturer optimises for something different — tool life, surface finish, chip control, or spindle power. Two suppliers can quote the same ISO grade and give you cutting speeds 30% apart, and each figure can be right for that supplier’s own geometry, edge preparation and coating.
That is why the number this calculator returns is a starting point, not a setting. Treat the catalogue figure as the middle of a band, then correct it on the first part: if the chips come off blue or the spindle load sits above roughly 80%, come down; if the finish is smeared and the chips are thin and stringy, come up. Write down what actually worked — that shop-specific number beats any published value.
A step drill combines two or more diameters in one tool, allowing a hole with a counterbore, countersink, or multiple diameters to be drilled in a single operation. The step length must provide adequate chip clearance and tool strength.
Step drills save cycle time when producing holes with multiple diameters (e.g., clearance hole + counterbore, or pilot hole + tap drill). They pay for themselves quickly in production runs over 100 parts. For one-offs, separate tools are usually more economical.
Yes, but each diameter must be sharpened to its original size. The step length shortens slightly with each sharpening. Most shops send step drills to a tool grinding service rather than attempting in-house sharpening. For carbide step drills, re-sharpening is less common due to the complex geometry.
The larger diameter should not exceed 3× the smaller diameter for carbide step drills. Beyond this, the tool becomes fragile at the transition. For large diameter jumps, consider using a separate tool for each diameter or a custom form tool with a reinforced transition.
Enter the two step diameters. The calculator shows the step diameters and an approximate step transition length. For custom step drills, send the exact diameters and lengths to your tooling supplier with the shank diameter and overall length specification.
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
DESIGNING A STEP DRILL? Step drills are almost always custom, so the drawing you send decides everything downstream. See what a Chinese tool shop needs from your drawing.
Tell us the part material, lot size, and target price. We’ll match a verified China factory and return a quotation within 48 hours.