FPS / Joule Calculator Pro
Muzzle energy is constant across BB weights — enter a measured FPS (or pick a spring) and see the equivalent FPS at every common weight, plus field-limit checks.
Muzzle energy
1.49 J
Velocity @ 0.20 g
400 FPS
Velocity across BB weights (same energy)
0.20 g
400
FPS
0.23 g
373
FPS
0.25 g
358
FPS
0.28 g
338
FPS
0.30 g
327
FPS
0.32 g
316
FPS
0.36 g
298
FPS
0.40 g
283
FPS
0.43 g
273
FPS
0.48 g
258
FPS
Field power limits
Checks your 1.49 J setup against typical caps. Limits vary by field — always confirm locally.
CQB / Indoor
Tight indoor play. Commonly ~350 FPS (0.20 g), usually no minimum engagement distance.
limit 1.14 J
350 FPS @ 0.20g
Field AEG (full-auto)
Typical outdoor full-auto cap. Commonly ~400 FPS (0.20 g).
limit 1.49 J
400 FPS @ 0.20g
Field AEG (high cap)
Higher outdoor cap at some fields. Commonly ~450 FPS (0.20 g).
limit 1.88 J
450 FPS @ 0.20g
DMR (semi-only)
Semi-auto only with a minimum engagement distance (often ~100 ft / 30 m).
limit 2.32 J
500 FPS @ 0.20g
Bolt-action Sniper
Single-shot bolt action with a longer minimum engagement distance.
limit 2.81 J
550 FPS @ 0.20g
Rate-of-fire estimator
Rough AEG estimate from gear ratio, motor Kv (RPM per volt) and battery voltage.
Estimated ROF
22 rps
Rounds / min
1320