Feeds & Speeds Steps/mm Critical Speed Force RPM / SFM

Steps per mm Calculator

Calculate stepper motor steps/mm for ballscrews, leadscrews, or belt drives. Results update in real-time.

Motor Settings

1 = direct drive. Values > 1 mean gear reduction.

Drive Mechanism

Common: 2mm, 4mm, 5mm, 8mm, 10mm. For multi-start screws, use the lead (not pitch).

Calculated Results

Steps per mm

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Use this value in your firmware (GRBL $100/$101/$102 or Marlin DEFAULT_AXIS_STEPS_PER_UNIT)

Resolution

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mm / step

Max Speed @ 50 kHz

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mm/min

Max Speed @ 100 kHz

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mm/min

Max Speed @ 200 kHz

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mm/min

Max speed depends on your controller's pulse frequency. GRBL on Arduino typically supports ~30 kHz. Dedicated motion controllers (e.g., Mach3/4, LinuxCNC) can reach 100-200 kHz.

Formula

Steps/mm = (Motor Steps × Microstepping × Gear Ratio) / Travel per Rev

Ballscrew/Leadscrew: Travel per Rev = Screw Lead (mm)
Belt & Pulley: Travel per Rev = Pulley Teeth × Belt Pitch (mm)

Frequently Asked Questions

How much microstepping should I use?

Higher microstepping gives finer resolution but reduces torque at high speeds and requires a faster pulse rate from your controller. For most CNC routers, 1/8 microstepping (8) is a solid default that balances resolution, torque, and speed. Use 1/16 or 1/32 only if you need extremely fine resolution (e.g., engraving or PCB milling) and your controller can handle the higher pulse rate. Full-step and half-step modes are rarely used because they cause more vibration and noise.

What is the difference between pitch and lead on a leadscrew?

Pitch is the distance between adjacent thread crests. Lead is the distance the nut travels in one full revolution of the screw. On a single-start screw, pitch equals lead. On multi-start screws (2-start, 4-start), the lead is pitch multiplied by the number of starts. For example, a 4-start screw with 2mm pitch has an 8mm lead. When configuring steps/mm, always use the lead, not the pitch. Common T8 leadscrews on budget machines are 4-start with 2mm pitch, giving an 8mm lead.

What are typical steps/mm values for common CNC setups?

Here are some common configurations:

  • GRBL shield + T8 leadscrew (8mm lead, 1/8 step): 200 steps/mm
  • Ballscrew 1605 (5mm lead, 1/8 step): 320 steps/mm
  • GT2 belt + 20T pulley (1/8 step): 40 steps/mm
  • GT2 belt + 20T pulley (1/16 step): 80 steps/mm
  • Ballscrew 1610 (10mm lead, 1/8 step): 160 steps/mm

If your calculated value does not match these common values, double-check your screw lead and microstepping settings.