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

Cell Count (S)

Battery 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.