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The ballistic coefficient compares a projectile's mass to the area it presents to the air. A higher value means the projectile keeps its speed better. This calculator uses the sectional-density form, BC = m / (i·d²), with the form factor i defaulting to 1 for a reference shape.
Compute the mass-over-area term that governs drag deceleration.
BC = m / (i · d²)
With mass in kilograms and diameter in metres the result is in kg/m². A form factor of 1 treats the projectile as the reference shape; values above 1 mean more drag for the same mass and calibre.
| Symbol | Meaning |
|---|---|
| m | Projectile mass, in kilograms. |
| d | Projectile diameter, in metres. |
| i | Form factor relative to the reference shape (dimensionless). |
| BC | Ballistic coefficient, in kilograms per square metre. |
A 10 g projectile (0.01 kg) with a 7.62 mm diameter has a cross-sectional term of 5.806×10⁻⁵ m², giving a ballistic coefficient of about 172 kg/m².
Continue with the Car Jump Distance Calculator, Conservation of Momentum Calculator, or the Displacement Calculator — or browse more kinematics tools and all physics calculators.
Not exactly. Published BC values are dimensionless and referenced to a standard drag model such as G1 or G7. This page reports the sectional-density form in SI units, which is proportional to those values.
Results are computed from the standard equations of classical mechanics. Unit conversions use the SI definitions published by NIST. Air resistance is ignored unless the calculator names a drag model.
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Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026