Question 1

What FPS is 1 joule on a 0.25g BB?

Accepted Answer

293 FPS. The formula: v = √(2E/m), converted to feet per second. On 0.25g (0.00025 kg), 1.0 J of energy equals 293 FPS.

Question 2

What's the max FPS for CQB with 0.25g BBs?

Accepted Answer

Most indoor CQB fields cap energy at 1.14 J, which is 313 FPS on a 0.25g BB. Always confirm with your field — some chrono everyone on 0.20g regardless of what you play with.

Question 3

Is 0.25g a good BB weight?

Accepted Answer

0.25g is a standard weight for stock and lightly upgraded AEGs. It's cheap and fast but drifts more in wind than heavier BBs.

Limit	Joules	Max FPS on 0.25g
Indoor CQB	1.14 J	313 FPS
Outdoor AEG	1.49 J	358 FPS
UK legal max (VCR Act)	1.32 J	337 FPS
Outdoor DMR	1.88 J	402 FPS
Bolt-action sniper	2.32 J	447 FPS

Velocity	Energy	Metric
100 FPS	0.12 J	30 m/s
120 FPS	0.17 J	37 m/s
140 FPS	0.23 J	43 m/s
160 FPS	0.30 J	49 m/s
180 FPS	0.38 J	55 m/s
200 FPS	0.46 J	61 m/s
220 FPS	0.56 J	67 m/s
240 FPS	0.67 J	73 m/s
260 FPS	0.79 J	79 m/s
280 FPS	0.91 J	85 m/s
300 FPS	1.05 J	91 m/s
320 FPS	1.19 J	98 m/s
340 FPS	1.34 J	104 m/s
360 FPS	1.51 J	110 m/s
380 FPS	1.68 J	116 m/s
400 FPS	1.86 J	122 m/s
420 FPS	2.05 J	128 m/s
440 FPS	2.25 J	134 m/s
460 FPS	2.46 J	140 m/s
480 FPS	2.68 J	146 m/s
500 FPS	2.90 J	152 m/s
520 FPS	3.14 J	158 m/s
540 FPS	3.39 J	165 m/s
560 FPS	3.64 J	171 m/s
580 FPS	3.91 J	177 m/s
600 FPS	4.18 J	183 m/s

FPS to Joules — 0.25g BB Chart

Field limits on 0.25g

Full conversion chart

FAQ

Other BB weights