Model torque decay from standstill to high speed. Inspect power, step rate, and safety margin. Tune inputs for smoother motion and better sizing decisions.
| Motor | Holding Torque (Nm) | Supply Voltage (V) | Corner Speed (RPM) | Load Torque (Nm) | Estimated Safe Speed (RPM) |
|---|---|---|---|---|---|
| NEMA 17 Example | 0.52 | 24 | 280 | 0.12 | 720 |
| NEMA 23 Example | 2.40 | 36 | 220 | 0.60 | 640 |
| High Torque Frame | 4.10 | 48 | 180 | 1.20 | 540 |
Corrected static torque = Holding torque × current factor × voltage factor × driver factor × microstep factor.
Current factor = Actual current ÷ rated current, capped to avoid unrealistic gain.
Voltage factor = (Supply voltage ÷ rated voltage)0.16, limited to a practical range.
Available torque at speed = Corrected static torque × [1 ÷ (1 + (speed ÷ corner speed)curve exponent)] × [1 − (speed ÷ maximum speed)1.18] + detent term.
Required torque = Load torque × safety factor.
Mechanical power = Torque × angular speed, where angular speed = 2π × RPM ÷ 60.
Enter the motor holding torque from the datasheet.
Set detent torque if you know it. Otherwise use a small value.
Enter the working load torque on the motor shaft.
Add motor rated voltage, supply voltage, rated current, and driver current limit.
Choose the microstep mode used by your driver.
Enter corner speed, maximum speed, curve exponent, and safety factor.
Set steps per revolution and the number of curve points.
Press calculate to view the torque curve, operating margin, power, and downloadable reports.
A stepper motor does not keep full torque at every speed. Static holding torque is highest at zero speed. Torque drops as pulse rate rises. Inductance slows current build-up. Back EMF also increases with speed. Both effects reduce usable torque. A torque curve calculator helps you predict this drop before testing hardware. It gives a faster design check. It also highlights weak operating zones. That can prevent stalls, missed steps, heat, and poor acceleration.
Many motion systems fail because sizing starts with holding torque alone. That value looks strong on paper. Yet real machines run above standstill. The motor must still overcome friction, inertia, and external load. The calculator estimates available running torque, pull-out speed, step rate, and power. It also applies driver efficiency, current ratio, supply voltage ratio, and microstepping effects. This creates a more realistic engineering estimate. It supports motor selection, gearing reviews, and safer speed targets for CNC, feeders, lab tools, printers, and indexing systems.
This page uses an empirical decay model. It scales holding torque with electrical and drive factors. Then it reduces torque as speed increases beyond the corner speed. A taper term pushes torque toward zero near the maximum speed. The result is not a factory dyno curve. It is a planning model. That makes it useful during early design, quoting, and troubleshooting. You can compare required torque against estimated available torque. You can also inspect the safe operating margin at each speed point.
Use the plotted curve to find a comfortable operating band. A good target stays below the predicted pull-out limit. It also keeps safety margin above zero. Higher supply voltage usually improves high-speed torque. Higher current can help too, within thermal limits. Smaller microsteps may reduce instantaneous torque slightly. Large loads and aggressive speeds increase stall risk. Validate important designs with vendor data and bench tests. Still, this calculator gives a strong first-pass view for smarter stepper motor sizing. It helps explain why some motors resonate or skip. Clear curve estimates support cleaner tuning and more reliable motion during commissioning and setup.
A torque curve shows how available motor torque changes with speed. Stepper motors produce their highest static torque at zero speed. Torque usually drops as stepping rate increases.
Corner speed is the point where torque decline becomes more pronounced. Below it, torque falls gradually. Above it, electrical limits reduce current build-up faster.
Higher drive voltage helps current rise faster in the windings. That usually improves high-speed torque. It does not mean unlimited speed, because heating and driver limits still matter.
Microstepping improves smoothness and resolution. Instantaneous incremental torque can drop compared with full stepping. The effect depends on drive tuning, current control, and load conditions.
No. This tool provides an engineering estimate. Final performance depends on winding inductance, resistance, rotor inertia, driver behavior, mechanics, and resonance.
Pull-out speed is the highest estimated speed where available torque still exceeds required torque. Running near that limit leaves little margin for disturbances.
Yes, but enter the motor-side load carefully or convert the load through the gear ratio first. Include losses for a more realistic margin.
A safety factor accounts for friction changes, acceleration spikes, supply variation, and modeling uncertainty. Positive margin improves reliability and reduces missed steps.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.