Extruder Gear Calculator — Gear Ratio & E-Steps

E-Steps Formula

• Filament per rev = Pi x Drive gear diameter / Gear ratio
• E-steps = (Motor steps x Microstepping) / Filament per rev
• Resolution = 1 / E-steps (mm per step)
• Max feed rate = Max RPM x Filament per rev / 60

The drive gear grips the filament. Its effective diameter determines how much filament moves per revolution. A gear reduction multiplies the steps and reduces speed proportionally, giving higher torque and finer control.

Max feed rate is a motor/RPM ceiling only. In practice your real maximum extrusion speed is limited by how fast the hotend can melt filament (volumetric flow), not by the stepper. A stock 0.4mm hotend manages roughly 10-15 mm³/s of PLA and a high-flow hotend roughly 30-40 mm³/s, which for 1.75mm filament (cross-section 2.405 mm²) caps the usable extruder feed around 4-6 mm/s (stock) to 12-17 mm/s (high-flow) — far below the RPM-limited figure shown here. Treat the calculated max feed rate as an upper bound the motor can reach, not an achievable print speed.