Workshop
Drill Speed Calculator
Correct drill RPM and feed for a bit size and material, with the estimated drilling time.
RPM = 1000 × Vc / (π × D)
Also called drill rpm · drilling speed chart
Engineering · 10 calculators
Workshop Calculators
Drill and spindle speeds, cutting speed, feed rate, pulley and gear ratios, thread pitch and tap drill sizes.
Workshop
Cutting Speed Calculator
Convert between cutting speed (SFM or m/min) and spindle RPM for turning and milling.
RPM = 1000 × Vc / (π × D)
Also called sfm calculator · surface feet per minute
Workshop
Feed Rate Calculator
Milling feed rate from chip load, flute count and spindle speed, with material removal rate.
feed = RPM × flutes × chip load
Also called ipm calculator · chip load calculator
Workshop
RPM Calculator
Convert between RPM, surface speed and angular velocity for shafts, wheels and tools.
surface speed = π × d × RPM
Also called revolutions per minute · rpm to rad/s
Workshop
Pulley Ratio Calculator
Pulley or sheave ratio from diameters, with driven speed, torque and belt speed.
ratio = driven diameter ÷ driver diameter
Also called sheave ratio · belt drive ratio
Workshop
Gear Ratio Calculator
Gear ratio from tooth counts or diameters, with output speed, torque and direction.
ratio = driven teeth ÷ driving teeth
Also called gearing calculator · gear teeth ratio
Workshop
Thread Pitch Calculator
Convert between thread pitch and threads per inch, with the standard metric coarse pitch.
pitch (mm) = 25.4 ÷ threads per inch
Also called tpi to pitch · threads per inch
Workshop
Tap Drill Size Calculator
Correct tap drill diameter for a thread, at any target percentage of thread engagement.
tap drill = D − (engagement % × 1.0825 × …
Also called tapping drill chart · drill size for tap
Workshop
Belt Length Calculator
Required belt length for a two-pulley drive from the diameters and centre distance.
L ≈ 2C + π(D₁ + D₂)/2 + (D₂ − D₁)² / 4C
Also called v belt length · pulley belt length
Workshop
Torque Calculator
Torque from force and lever arm (τ = F·r), solving for any variable, in N·m and lb·ft.
τ = F × r × sin θ (θ = 90° for maximum to…
Also called torque formula · moment of force
Key workshop formulas
| Drill Speed | RPM = 1000 × Vc / (π × D) |
|---|---|
| Cutting Speed | RPM = 1000 × Vc / (π × D) |
| Feed Rate | feed = RPM × flutes × chip load |
| RPM | surface speed = π × d × RPM · ω = 2π × RPM / 60 |
| Pulley Ratio | ratio = driven diameter ÷ driver diameter |
| Gear Ratio | ratio = driven teeth ÷ driving teeth |
| Thread Pitch | pitch (mm) = 25.4 ÷ threads per inch |
| Tap Drill Size | tap drill = D − (engagement % × 1.0825 × pitch) |
| Belt Length | L ≈ 2C + π(D₁ + D₂)/2 + (D₂ − D₁)² / 4C |
| Torque | τ = F × r × sin θ (θ = 90° for maximum torque) |
Workshop questions
Does a higher gear ratio mean more speed?
No — a higher numeric ratio means more torque and lower output speed. Overdrive ratios are below 1.