Safety first. Always check the field rules and organiser's instructions before buying or using any equipment.
Joules, FPS and BB weight converter
Choose the value you want to calculate and enter the other two.
This is a theoretical conversion. The field chrono result with the BB weight actually used always takes priority.
Joules, FPS and BB weight describe different parts of the same shot. This converter lets you enter two values and calculate the third immediately.
How to use it
Choose Joules, FPS or BB weight depending on the value you need. Then enter the other two values. Decimal commas and points are both accepted.
When comparing a replica with a field limit, always use the actual BB weight used for the chrono test.
What it calculates
Energy is calculated with J = ½ × m × v², where mass is measured in kilograms and velocity in metres per second. The converter automatically transforms grams and FPS into those units.
Changing BB weight does not add energy by itself. Some replicas—especially certain gas or HPA systems—can nevertheless exhibit joule creep: measured energy may rise with a heavier BB because of how the available air or gas volume is used.
Use the result as a reference. The field's chrono reading, following its procedure and stated BB weight, determines whether a replica complies with its limits.