FPS / Joule CalculatorFree
Muzzle energy is constant across BB weights ā enter a measured FPS (or pick a spring) and see the equivalent FPS at every common weight, plus field-limit checks.
Velocity across BB weights (same energy)
Field power limits
Checks your 1.49 J setup against typical caps. Limits vary by field ā always confirm locally.
Most UK skirmish sites cap around 1 J (~328 FPS on 0.20 g) for general play. Single-shot/sniper allowances can be higher; always confirm your site's chrono limits.
Typical US indoor / CQB cap (~350 FPS on 0.20 g), usually with no minimum engagement distance.
Common US outdoor full-auto cap (~400 FPS on 0.20 g).
Higher cap for DMR / semi and some sniper roles at many US outdoor fields (~450 FPS on 0.20 g), typically with a minimum engagement distance.
Sniper / DMR cap at most US milsim events (~500 FPS on 0.20 g), semi-auto only with a longer minimum engagement distance.
Highest sniper cap allowed at some US milsim events (~550 FPS on 0.20 g), bolt-action only with the longest minimum engagement distance.
Check against a country's legal limit
Compares your 1.49 J setup to a country's statutory or licence threshold. These are legal thresholds, not field caps. Fields and local rules are often stricter. Not legal advice.
1.49 J is over the 1.3 J full-auto cap but within the 2.5 J semi / single-shot cap.
Single shot up to 2.5 J; full-auto up to 1.3 J under the airsoft permitted-activity defence.
Always confirm the current rules in your area. See the airsoft laws guide for the full country breakdown.
Rate-of-fire estimator
Rough AEG estimate from gear ratio, motor Kv (RPM per volt) and battery voltage.