Ballistic Coefficient Calculator
Use our ballistic coefficient calculator to estimate ballistic coefficient (B) from mass (m), cross-sectional area (A), and drag coefficient (C). Includes what ballistic coefficient is, ballistic coefficient explained, the ballistic coefficient formula, and guidance on whether a higher or lower ballistic coefficient is better.
What Is Ballistic Coefficient?
Ballistic coefficient (often abbreviated BC) describes how well a projectile resists air drag in flight. In general, a higher ballistic coefficient means the projectile slows down less from air resistance, retains velocity better, and is less affected by wind drift (all else equal).
You’ll see ballistic coefficient used most often for bullets, but the general idea applies to any projectile moving through air. Different fields and ballistics tables sometimes define BC in slightly different ways, which is why it’s helpful to know what formula your calculator is using.
This ballistic coefficient calculator uses the physics-style definition based on mass, drag coefficient, and cross-sectional area.
Ballistic Coefficient Formula
In this calculator, ballistic coefficient is computed as mass divided by drag coefficient times cross-sectional area.
B increases with higher mass and decreases with higher drag coefficient or larger cross-sectional area.
That combination generally means less deceleration from drag.
How to Calculate Ballistic Coefficient
- 1
Enter the projectile mass (m).
- 2
Enter the cross-sectional area (A) of the projectile.
- 3
Enter the drag coefficient (C).
- 4
The calculator computes B = m / (C · A).
Frequently Asked Questions
Ballistic coefficient is a measure of how well a projectile overcomes air resistance. Higher values generally indicate better drag performance (better velocity retention and less wind drift), depending on the convention used.
It summarizes how mass, shape/drag (via drag coefficient), and size (cross-sectional area) combine to determine how strongly air resistance slows the projectile.
In most practical shooting contexts, higher is generally better for long-range performance (more velocity retained and less wind drift). However, “better” depends on your use case and the specific BC convention used.
What counts as “good” depends on projectile type and speed range. Compare BC values within the same standard/convention for meaningful comparisons.
People often use “bullet coefficient” to mean ballistic coefficient (BC), describing how efficiently a bullet moves through air.
This calculator uses B = m/(C·A). In many firearms contexts, published BC values may be based on standard drag models (like G1 or G7) derived from measured velocity decay over distance, which can differ from this simplified physics definition.
In practice, BC is often estimated by measuring how velocity drops over a known distance and fitting a drag model (commonly G1 or G7). That method requires downrange velocity data (often from chronographs) and a chosen drag standard, so it’s not the same as the simple B = m/(C·A) calculation used here.