FPS (Feet Per Second) is a critical measurement in airsoft that indicates how fast a BB travels when leaving the barrel of your airsoft gun. Understanding FPS is essential for safety, field compliance, and optimizing your gun's performance.
What is FPS?
FPS measures the muzzle velocity of your airsoft gun - the speed at which a BB exits the barrel. It's measured using a chronograph, a device that calculates velocity based on the time it takes a BB to pass through sensors.
Example: A gun shooting at 350 FPS means the BB travels at 350 feet per second, or approximately 238 mph.
Standard FPS Ranges by Gun Type
- Low-Power Spring Pistols: 150-250 FPS (backyard plinking, not field-legal)
- Airsoft Pistols (GBB/AEP): 250-350 FPS
- AEGs (Assault Rifles/SMGs): 330-400 FPS
- DMRs (Designated Marksman Rifles): 400-450 FPS
- Sniper Rifles: 450-550 FPS
- Heavy Support Weapons: 350-450 FPS
Field FPS Limits
Airsoft fields enforce FPS limits to ensure player safety. Exceeding these limits can result in being banned from play or required to use your gun with a minimum engagement distance (MED).
Common Indoor CQB Limits
- Full Auto: 350 FPS maximum
- Semi Auto Only: 400 FPS maximum
- No Minimum Engagement Distance: For guns under 350 FPS
Common Outdoor Field Limits
- AEGs/Rifles: 400 FPS (0.20g BB), no MED or 10-20 ft MED
- DMRs: 450 FPS (0.20g BB), 50-75 ft MED, semi-auto only
- Bolt Action Snipers: 500-550 FPS (0.20g BB), 100 ft MED
FPS and BB Weight
FPS measurements are standardized using 0.20g BBs. When using heavier BBs, your FPS will decrease even though the energy remains the same. This is why fields measure using 0.20g BBs for consistency.
Example: A gun shooting 400 FPS with 0.20g BBs might only shoot 350 FPS with 0.25g BBs, but both have similar kinetic energy.
Joule Creep and Energy
Some fields use Joules instead of FPS to measure energy, as it's more accurate across different BB weights. Joule creep occurs when a gun gains energy with heavier BBs, particularly in HPA systems and some gas guns.
- 1.0 Joule: Approximately 328 FPS with 0.20g BBs
- 1.5 Joules: Approximately 400 FPS with 0.20g BBs
- 2.0 Joules: Approximately 462 FPS with 0.20g BBs
- 2.3 Joules: Approximately 500 FPS with 0.20g BBs
How to Measure FPS
Using a Chronograph
- Load your gun with 0.20g BBs (standard testing weight)
- Point the gun through the chronograph sensors
- Fire 3-5 shots and record the readings
- Calculate the average FPS
- Verify compliance with field limits
Field Chronograph Testing
Most fields require chronograph testing before every game session. Arrive early to have your guns tested and bring 0.20g BBs for testing if required.
Adjusting Your Gun's FPS
Increasing FPS
- Upgrade to a stronger spring
- Improve air seal (cylinder head, piston head, nozzle)
- Use tighter bore barrel
- Increase gas pressure (gas guns)
Decreasing FPS
- Install a weaker spring
- Cut coils from existing spring (not recommended)
- Use short-stroke kit
- Adjust HPA regulator pressure
- Use lower-pressure gas
FPS vs Performance
Higher FPS doesn't always mean better performance. Accuracy, consistency, and proper hop-up adjustment are often more important than raw velocity.
- Accuracy: Quality barrels and hop-up affect accuracy more than FPS
- Range: Proper hop-up with heavy BBs extends range more than high FPS
- Consistency: FPS variation should be within 10-15 FPS for good performance
Safety Considerations
- Never exceed field FPS limits - it's a safety hazard
- Always chrono test before playing
- Respect minimum engagement distances for high-FPS guns
- Higher FPS increases injury risk - use responsibly
- Eye protection is mandatory regardless of FPS