What does KV mean on a brushless motor?

KV is the motor velocity constant — it tells you how many RPM the motor will spin per volt applied with no load. A 2200KV motor on 11.1V (3S LiPo) spins at 2200 x 11.1 = 24,420 RPM unloaded. Under load (with a propeller or wheels), actual RPM is typically 70-85% of no-load speed.

Not necessarily. Higher KV means more speed but less torque. Low KV motors (below 1000KV) suit large propellers and slow-flying models. High KV (2000+) suits small, fast models. Medium KV (1000-2000) is a good all-rounder. Match the KV to your application.

How do I choose the right KV for my RC plane?

Trainer/glider: 800-1200KV. Sport aerobatics: 1000-1500KV. Racing: 2000-2800KV. Micro drones: 2500-3500KV. The motor should spin the propeller at the recommended RPM range for your prop diameter — typically 5000-8000 RPM for larger props.

What is the load factor?

Under load (turning a prop or wheels), the motor cannot reach its no-load RPM. The load factor is the percentage of no-load RPM achieved under load. Typically 75-85% for a correctly matched prop/motor combo. An overloaded motor runs at 60-70% and wastes energy as heat.

ModelCalcs

Motor KV Calculator — RPM from KV & Voltage

Work out motor RPM from KV rating and battery voltage, or find the right KV for your needs.

Motor KV Rating

Motor KV rating (RPM per volt)

Cell Count (S)

Select an option for cell count (s)

Battery Type

Select the type

Load Factor (%)

75-85% typical under load

How We Calculate This

Multiplies motor KV rating by battery voltage to calculate RPM, then applies a load factor for real-world speed.

Formula

No-load RPM = KV x Battery voltage (fully charged)
Loaded RPM = No-load RPM x Load factor %
Battery voltage = Cells x Cell nominal voltage

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.