Tool · Airsoft

How many BBsper second?

Calculate your AEG's rate of fire from motor, battery voltage and gear ratio. Compare torque-up, standard and high-speed builds.

MOTOR RPM AT NOMINAL VOLTAGE

RPM

From the motor's datasheet (e.g. 25,000 RPM @ 8.4 V)

MOTOR NOMINAL VOLTAGE (V)

Typically 8.4 V for AEG motors. Some HPA setups use 11.1 V.BATTERY VOLTAGE (V)

11.1 V LiPo 3S · 7.4 V LiPo 2S · 9.6 V NiMH

GEAR RATIO

First number of the ratio (18 for 18:1, 13 for 13:1, etc.)

BBS / SECOND26.9 BB/s

REAL MOTOR RPM29,071 RPM

ROF PER MINUTE1,615 RPMCyclic rate (rounds per minute)

ROF = RPM × (V / V_nom) / ratio / 60BB/s × 60 = BB/min

/ How it works

The principles behind the math

Voltage = motor speed

Brushed motors scale linearly with voltage. Going from 7.4 V to 11.1 V boosts ROF ~50% — but also draw and stress on piston and gears.

Gears are a tradeoff

Speed gears (16:1, 13:1) → more ROF, less torque, capped under M120 springs. Torque gears (32:1) → low ROF but pull heavy springs without straining the motor.

High ROF, short life

Above 25 BB/s you need full-metal-teeth piston, hardened steel gears, correct AOE, MOSFET with active braking. Without those, the gearbox grenades in a few games.

Theoretical calculation. Real ROF also depends on spring rate, AOE, grease viscosity, motor condition and battery sag under load.