Airsoft Calculators
Airsoft Velocity & Energy Estimator
Estimate muzzle velocity and energy from barrel length, spring rating, and BB weight. Results are approximate—chrono your setup for field limits.
Reference: 300 mm. Longer barrels give diminishing returns if cylinder volume is matched.
Approx base: 380 fps @ 0.20 g, ~300 mm
Common: 0.20–0.32 g (outdoor often 0.28–0.32 g).
Estimated velocity
0.0 fps
0.00 m/s
Estimated energy
0.000 J
at muzzle
Assumptions
Base map is typical FPS with 0.20 g at ~300 mm; energy scaled by barrel length; velocity derived from E = ½·m·v².
How it works (math)
1) Convert the base spring FPS (with 0.20 g @ 300 mm) to Joules:
2) Adjust for barrel length with a bounded factor:
3) Convert energy back to velocity for your BB mass:
E₀ = ½·m·v².2) Adjust for barrel length with a bounded factor:
E = E₀ · (1 + a·tanh((L − 300)/b)), with a = 0.06, b = 200.3) Convert energy back to velocity for your BB mass:
v = √(2E/m).
Airsoft RPS (Rate of Fire) Estimator
Estimate rounds per second (RPS) from gear ratio and either known motor RPM or TPA + battery voltage. Includes a load factor and an optional DSG toggle.
This is the overall ratio (motor revolutions per one full cycle). Standard single-sector gears assumed.
Known RPM
TPA + Battery
Typical AEG motors: ~18k–45k rpm no-load depending on model and voltage.
Multiplies no-load RPM to approximate real under-load RPM (seal, spring, bearings, lube, wiring, etc.).
Estimated RPS
0.0 rps
0 rpm under load
Estimated RPM (no-load)
0 rpm
0 rounds/min
Assumptions
Ideal cycles per second = (RPM ÷ ratio ÷ 60). Under-load RPM = no-load × efficiency. DSG doubles cycles. Real builds vary with compression, spring, short-stroke teeth, pre-cocking, MOSFET timing, and motor torque.
Math details
1) If using TPA:
KV ≈ 45000 / TPA (rpm/V, heuristic) → RPM₀ = KV × V.2) Under-load RPM:
RPM = RPM₀ × η, where η is the efficiency slider (0.60–0.95).3) RPS:
RPS = (RPM ÷ ratio ÷ 60) × (DSG ? 2 : 1).