Ballistic Coefficient Calculator
Calculate ballistic coefficient and related parameters for projectiles
Ballistic Coefficient (BC) is a measure of a projectile's ability to overcome air resistance in flight. It compares the projectile's performance to a standard projectile. The higher the BC, the better the projectile is at maintaining its velocity and resisting wind deflection.
Key points about Ballistic Coefficient:
- Higher BC values indicate better aerodynamic efficiency
- BC affects trajectory, wind drift, and retained velocity
- Most modern rifle bullets have BC values between 0.2 and 0.6
- BC is dependent on bullet shape, weight, and diameter
The Ballistic Coefficient is calculated using the following formula:
BC = SD × Form Factor
Where:
- SD (Sectional Density) = Bullet Weight (lb) / Bullet Diameter² (in²)
- Form Factor is a coefficient based on the bullet's shape
This calculator uses the G1 drag model, which is the most common reference standard for small arms projectiles.
Sectional Density (SD) is a ratio of a bullet's weight to its diameter. It's an important factor in determining:
- Penetration potential
- Trajectory characteristics
- Terminal performance
- Overall efficiency
Typical SD values and their implications:
- 0.150-0.200: Light for caliber
- 0.200-0.250: Medium for caliber
- 0.250-0.300: Heavy for caliber
- >0.300: Very heavy for caliber
Form factors represent how aerodynamic a bullet shape is compared to a standard reference projectile. Common bullet shapes and their typical form factors:
- Flat Base (1.0): Standard reference shape
- Spitzer (0.9): Pointed nose, improved aerodynamics
- Spitzer Boat Tail (0.75): Pointed nose with tapered base
- VLD (0.6): Very Low Drag, optimized for long range
- Round Nose (1.2): Traditional design, higher drag
What is a good ballistic coefficient?
A good BC depends on the intended use. For long-range shooting, BCs above 0.5 are considered excellent. For general purpose shooting, BCs between 0.2 and 0.4 are typical and adequate.
Why is ballistic coefficient important?
BC is crucial for predicting bullet trajectory, wind drift, and retained velocity. Higher BC bullets generally perform better at long range and are less affected by wind.
How does BC affect shooting performance?
A higher BC means the bullet will maintain velocity better, resist wind drift more effectively, and generally shoot flatter at long range. This makes accurate shot placement easier, especially under challenging conditions.