Pellet Input Parameters
Current Calculation Result
No calculation yet. Enter pellet details and press calculate.
Ballistic coefficient (BC): –
Sectional density (SD): – lb/in²
Muzzle velocity:
Muzzle energy: ft·lb ( J)
Estimated drag category:
Saved Pellet Comparisons
Each time you calculate, the result is added below for comparison and export.
| # | Pellet name | Weight (gr) | Diameter (in) | Diameter (mm) | Form factor | SD (lb/in²) | BC | Velocity | Energy (ft·lb) | Energy (J) |
|---|
Example pellet data table
The following table illustrates typical ballistic coefficients for popular pellet weights and calibres. Values are approximate and will vary across manufacturers and exact shapes.
| Pellet type | Calibre (in) | Weight (gr) | Estimated form factor | Approximate BC | Intended use |
|---|---|---|---|---|---|
| Domed medium weight | 0.177 | 8.4 | 1.00 | 0.020 | General target, short hunting |
| Heavy domed | 0.22 | 18.0 | 0.95 | 0.032 | Medium range hunting |
| Light pointed | 0.177 | 7.0 | 1.10 | 0.017 | Short range pest control |
| Heavy slug | 0.25 | 33.0 | 0.85 | 0.050 | Long range precision |
Formula used for ballistic coefficient
This calculator uses a sectional density based approach. First, pellet mass is converted into pounds of mass. The diameter is converted to inches if necessary. Sectional density is then:
SD = m / d²
- m = pellet mass in pounds
- d = pellet diameter in inches
Ballistic coefficient is computed by dividing sectional density by the form factor:
BC = SD / i
The form factor i represents how streamlined the pellet is relative to a reference drag model. More efficient shapes have lower values, which increase the ballistic coefficient.
How to use this ballistic coefficient calculator
- Enter a short name for the pellet or load you are testing.
- Measure pellet weight and choose whether you are entering grains or grams.
- Enter pellet diameter and choose whether your value is in inches or millimetres.
- Select a pellet shape profile or leave it as custom and type your own form factor.
- If you have a chronograph reading, enter muzzle velocity and choose the matching unit.
- Click Calculate ballistic coefficient to generate BC, sectional density, and muzzle energy.
- Repeat the process with different pellets. Each calculation is automatically added to the comparison table, which you can export as CSV or PDF.
By comparing ballistic coefficient and energy values across pellets, you can better match ammunition to your barrel, energy level, and desired shooting distance.
Understanding pellet ballistic coefficient in practice
Ballistic coefficient expresses how efficiently a pellet moves through air. Higher values show that a projectile resists drag better, preserving velocity and energy over distance. This calculator helps shooters compare pellets objectively using measurable inputs instead of relying only on marketing descriptions or rough guesses.
1. Why ballistic coefficient matters for airguns
Airgun pellets are relatively light, so wind and drag can change their path quickly. Knowing ballistic coefficient supports better scope dope, ethical hunting decisions, and more consistent competition performance, especially when shooting in variable conditions beyond basic plinking ranges.
2. Role of sectional density in pellet performance
Sectional density combines pellet weight and diameter into a single parameter. A heavier pellet for the same calibre usually has higher sectional density. That extra mass behind the frontal area helps the pellet hold momentum, penetrate more effectively, and carry energy further downrange.
3. Comparing pellet shapes and drag behaviour
Different pellet shapes create different drag profiles. Wadcutter pellets cut clean holes in paper but shed velocity rapidly. Domed and pointed designs retain speed better for field use. Modern slug projectiles act more like small bullets, offering very high ballistic coefficients when matched with suitable barrels.
4. Using muzzle velocity alongside ballistic coefficient
Muzzle velocity alone does not describe trajectory. Two pellets with identical speed but different coefficients will behave differently beyond close range. Combining measured muzzle velocity with ballistic coefficient gives a clearer prediction of drop, drift, and retained energy across your typical engagement distances.
5. Optimising pellet choice for specific distances
Short range plinking may favour inexpensive, lighter pellets with modest efficiency. For pest control or challenging targets at longer ranges, higher ballistic coefficient becomes more important. This calculator lets you store several candidates and quickly find which option best fits the distances you normally shoot.
6. Recording data for tuning and repeatability
Pellet testing can generate many chronograph strings and notebook entries. By exporting table data as CSV or PDF, you can preserve your findings, match them with group sizes, and track changes after regulator adjustments, barrel cleaning routines, or environmental shifts affecting air density.
7. Limitations of estimated ballistic coefficients
Calculated coefficients are still approximations, not laboratory measurements. Pellets vary between lots, and real flight includes yaw and changing air density. Treat results as guidance, then verify trajectories and holdovers outdoors using careful range work.
Frequently asked questions
1. What is a good ballistic coefficient for typical airgun pellets?
Most diabolo pellets fall between 0.015 and 0.040. Values around 0.020–0.030 are common for general use. Slug projectiles may show significantly higher coefficients when matched with a suitable barrel and power level.
2. Do heavier pellets always shoot better than lighter pellets?
Heavier pellets often keep energy and resist wind better, but they require sufficient power and proper barrel twist. Very heavy pellets in a weak platform can arc excessively and become less practical beyond modest distances.
3. Can this calculator replace full trajectory software?
No, this tool focuses on estimating ballistic coefficient, sectional density, and energy. Dedicated trajectory programs also model drop, drift, and atmospheric effects across specific distances, but they still rely on accurate ballistic coefficient input values.
4. How accurate are ballistic coefficients calculated from basic pellet data?
Accuracy depends on quality of inputs and how closely your pellets match assumed drag behaviour. Values are generally good for comparison purposes but may differ from manufacturer laboratory measurements or advanced Doppler radar derived coefficients.
5. Why does the table store results instead of just showing the latest value?
Storing multiple calculations lets you compare several pellets side by side. You can spot trends across calibres, shapes, and weights, then export the data into spreadsheets or PDF notes for later analysis and field reference.
6. Do I need a chronograph to use this calculator effectively?
You can estimate ballistic coefficient without velocity, but adding measured muzzle speed unlocks energy calculations. Chronograph data improves understanding of how efficiently your platform propels each pellet and helps confirm whether heavier options remain within safe limits.