Drill & Tap Calculators
Calculate optimal cutting speed, feed rate, and cycle time. Look up tap drill sizes for metric and imperial threads.
Drill Speed Command
OPTIMAL
Tool Parameters
Cutting Data
Computed cutting parameters
How to Calculate Drilling Speed for Stainless Steel
The standard formula for drill RPM (revolutions per minute) is:
- Vc Cutting speed. The surface speed in meters per minute (m/min).
- D Diameter. The drill bit diameter in millimeters (mm).
- ×1000 Conversion factor from meters to millimeters.
Why speed matters for stainless steel
Stainless steel (especially 304 and 316 grades) has a tendency to work harden. If your drill speed is too high, you generate excessive heat, causing the material to harden instantly and burn your drill bit. If too low, productivity suffers.
Drill bit selection
HSS Co (Cobalt)
Best for handheld drilling or standard drill presses. The cobalt content adds heat resistance, crucial for stainless steel.
Solid Carbide
Essential for high-production CNC machining. Allows for 3–4× faster cutting speeds but requires a rigid setup.
Tap Drill Size Calculator
Select thread → Get drill size
Thread standard
Thread Size
The tap drill size provides approximately 75% thread engagement, which is the industry standard for optimal strength and tap life.
Required drill sizes
How to Use the Tap Drill Size Chart
The standard formula for calculating tap drill size is:
- Major Ø The nominal thread size (e.g. 8 mm for M8).
- Pitch The distance between thread crests in mm (e.g. 1.25 mm for M8 coarse).
- Result M8 × 1.25 → Tap Drill = 8 − 1.25 = 6.75 mm (rounded to 6.8 mm).