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.

/ Frequently asked questions

Quick answers about airsoft rate of fire

What RPS is good for airsoft?▾

A stock AEG usually shoots around 12–18 RPS, which is plenty for general play. 20–25 RPS is a strong, reliable upgrade target. Above 25–30 RPS you're into high-speed territory that needs hardened internals and many fields cap full-auto rate of fire anyway.

How do I calculate rate of fire on an AEG?▾

Rate of fire scales with motor RPM and battery voltage and divides by the gear ratio: faster motor or higher voltage raises RPS, while a taller torque ratio lowers it. Enter your motor RPM, battery voltage and gear ratio above to get RPS and RPM.

Does a higher voltage battery increase rate of fire?▾

Yes. Brushed AEG motors scale roughly linearly with voltage, so moving from a 7.4 V to an 11.1 V LiPo raises rate of fire by about 50%. It also increases current draw and stress on the piston and gears, so build accordingly.

What is the difference between torque-up and high-speed gears?▾

Speed gears (16:1, 13:1) spin the sector gear faster for higher RPS but lose torque, so they struggle with heavy springs. Torque gears (32:1) give lower RPS but pull strong springs easily without straining the motor. Standard 18:1 is the balanced middle.

What RPM motor do I need for high speed?▾

Stock motors sit near 22,000 RPM. High-speed builds use 30,000+ RPM motors paired with speed gears and a strong battery. For a heavy spring you want a high-torque motor instead — raw RPM without torque just bogs down.

Is a high rate of fire bad for my gearbox?▾

It can be. Above roughly 25 RPS the gearbox sees big stress, so you need a full-metal-teeth piston, hardened steel gears, correct angle of engagement and a MOSFET with active braking. Without those upgrades a high-ROF gearbox wears out fast.

/ Related reading