Drill and tap calculator
Get drilling RPM, penetration rate and drill-point allowance, then look up the right tap drill for the thread you need.
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Drilling CalculationsDrilling RPM, feed per revolution, point allowance and cutting time.Tap Drill & Thread % CalculatorPercent of thread for any drill (cut and form taps), 75 / 65 / 50% tap drills, UNC / UNF / metric chart with thread limits, every thread to 4 in and M64, pipe taps and STI / Helicoil.
Drilling and tapping speeds by size
- Tap speeds and feeds: RPM, IPM and G84 code for every UNC, UNF and metric tap, e.g. 1/4-20, M6×1.
- Drill speeds and feeds: decimal, mm, tap use and RPM/feed by material for each drill, e.g. 1/4", #7, letter F.
What it covers
- Drilling RPM and feed per revolution with spindle limit
- Drill-point allowance from point angle
- Tap drill sizes for UNC, UNF and metric coarse/fine
- Cutting-only time, with pecks and rapids clearly excluded
Common questions
- What tap drill do I use for 1/4-20?
- A #7 drill (0.201 in) gives roughly 75% thread. Open the tap drill chart for every size.
- How is drill point length calculated?
- Point length = (D ÷ 2) ÷ tan(point angle ÷ 2). A 118° point is about 0.3 × D.
Reference charts
- Unified tap drill chart (UNC / UNF / UNEF)
- Metric tap drill chart (coarse and fine)
- Pipe tap drill chart (NPT, NPTF, BSPT)
- Decimal equivalent drill chart (inch and metric)
- Tap drill chart
- Roll tap (form tap) drill chart
- Helicoil / STI tap drill chart
- Drill size chart
- Letter drill size chart (A–Z)
- Number (wire gauge) drill size chart #1–#97
- Fractional drill size chart (1/64–1 in)
- Metric drill size chart (1–20 mm)
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