Airgun Power Calculator

GEOFF WILSON'S • AIRGUN TOOLS

Airgun Power & Chronograph Calculator

Look up pellet weights, calculate muzzle energy or analyse a full shot string with graphs and printable reports.

Quick calculator

Already know the pellet weight? Enter FPS and grains.

Velocity (FPS) Weight (grains)

—ft·lb

Choose your pellet or slug

Shared between both modes

1 Calibre

Projectile type

2 Find your pellet or slug

Matching products

Search above to narrow the dropdown, or choose from the full list.

Pellet weight (editable)

Choose a product or enter a measured weight.

3 Chronograph velocity

Enter a measured muzzle velocity from your chronograph.

CALCULATED MUZZLE ENERGY

—ft·lb

— joules

Choose a pellet or enter its weight, then enter a velocity.

Enter your readings

No account needed

Chronograph velocities

Enter one reading per line, or separate values with commas, spaces or semicolons. Numbers only, using a decimal point. Switching FPS/m/s converts your existing readings.

Readings are in

Projectile weight (shared with calculator)Not selectedSelect a pellet above, or enter its weight manually.

Paste your chronograph readings, or load a sample string to try it.

Shot-by-shot graph

A visual record of velocity changes through the string.

Show

Shot readings Average

Your graph will appear here after you enter two or more readings.

Tip: hover over any point to see the exact reading.

Optional PDF report details (airgun, ammunition, test date and notes)

Airgun / rifle Pellet / slug Actual test date and time (if known) Test notes

The PDF automatically includes its generation date and time. Enter a separate test date only if the shots were actually measured then. Nothing is uploaded.

Individual shots

Lowest and highest readings highlighted

Shot	Velocity (FPS)	Energy (ft·lb)	Energy (J)
Enter some readings to populate this table.

Understanding the results

Extreme spread (ES) is the difference between the fastest and slowest shot. Standard deviation (SD) describes how spread out readings are around the average; a lower SD usually indicates more consistent velocities. Neither number by itself proves accuracy on target.

Muzzle energy is estimated from pellet mass and measured velocity: ft·lb = grains × FPS² ÷ 450240. For reliable results, use your actual pellet weight and the same chronograph setup for the whole string. This is an informational calculator, not a certified power test.

All calculations and graph creation happen in your browser. The tool does not send your shot readings to an external calculation service.