Calculate ballistic coefficient, sectional density, drag force, and muzzle energy for projectiles. Compare G1/G7 models with built-in presets.
The **Ballistic Coefficient Calculator** quantifies how well a projectile overcomes air resistance. A higher ballistic coefficient (BC) means the projectile retains velocity and energy better over distance — a critical metric for long-range shooting, ammunition selection, and aerodynamic engineering.
BC is defined as the ratio of sectional density to drag coefficient, and it depends on the projectile's mass, caliber, and aerodynamic shape. This calculator gives you BC in both SI (kg/m²) and traditional imperial (lb/in²) units, plus sectional density, form factor, drag force, deceleration, and muzzle energy. Choose from common projectile presets or enter custom values.
Whether you are comparing ammunition, designing a projectile, or studying external ballistics, the built-in comparison table and velocity-decay estimates give you actionable data. Support for both G1 (flat-base) and G7 (boat-tail) drag models ensures the results align with modern ballistic software.
Use the preset examples to load common values instantly, or type in custom inputs to see results in real time. The output updates as you type, making it practical to compare different scenarios without resetting the page.
Choosing ammunition or designing projectiles without understanding BC leads to inaccurate range estimations. This calculator provides instant ballistic data for any projectile, saving time and enabling informed comparisons.
This tool is designed for quick, accurate results without manual computation. Whether you are a student working through coursework, a professional verifying a result, or an educator preparing examples, accurate answers are always just a few keystrokes away.
BC = m / (Cd × A) Sectional Density: SD = m / A Drag Force: F_d = ½ ρ v² Cd A Form Factor: i = Cd / Cd_ref (G1 ref = 0.5191) Muzzle Energy: KE = ½ m v² where m = mass, A = cross-section area, Cd = drag coefficient, ρ = air density, v = velocity.
Result: BC ≈ 0.505 (SI), 0.393 (imperial), muzzle energy 3 346 J
A 147-grain 7.62 NATO round with Cd 0.393 has a moderate BC of about 0.39 imperial, retaining energy well out to 500 m.
Use consistent units throughout your calculation and verify all assumptions before treating the output as final. For professional or academic work, document your input values and any conversion standards used so results can be reproduced. Apply this calculator as part of a broader workflow, especially when the result feeds into a larger model or report.
Most mistakes come from mixed units, rounding too early, or misread labels. Recheck each final value before use. Pay close attention to sign conventions — positive and negative inputs often produce very different results. When working with multiple related calculations, keep intermediate values available so you can trace discrepancies back to their source.
Enter the most precise values available. Use the worked example or presets to confirm the calculator behaves as expected before entering your real data. If a result seems unexpected, compare it against a manual estimate or a known reference case to catch input errors early.
BC measures a projectile's ability to overcome air resistance. Higher BC → less drag → better long-range performance. Understanding this concept helps you apply the calculator correctly and interpret the results with confidence.
G1 uses a flat-base reference shape; G7 uses a boat-tail shape. Most modern rifle bullets are better described by G7.
SD is mass divided by cross-sectional area — it indicates penetration potential independent of shape. Use this as a practical reminder before finalizing the result.
Lower air density at altitude reduces drag, effectively increasing the projectile's BC performance. Understanding this concept helps you apply the calculator correctly and interpret the results with confidence.
For rifle bullets, BC > 0.5 (G1) is considered high; match-grade long-range bullets often exceed 0.6.
Spin stabilises the bullet and reduces yaw, keeping the effective drag coefficient close to its ideal value. Keep this note short and outcome-focused for reuse.