What is Ballistic Coefficient?

Use this calculator to compute Ballistic Coefficient values with step-by-step solutions.

How do I use this calculator?

Enter the required values; results and step-by-step derivation update automatically.

Where is Ballistic Coefficient used?

Kinematics, engineering, research, and related scientific disciplines.

What formulas does this use?

All standard ballistic coefficient formulas are applied and shown step-by-step in the results.

Can I get step-by-step solutions?

Yes. The calculator shows a full step-by-step derivation when results are displayed.

How accurate are the results?

Results use standard floating-point arithmetic (~15 significant digits). Suitable for education and professional use.

5 more

MECHANICSKinematicsPhysics Calculator

🎯

Ballistic Coefficient - Projectile Air Resistance

Ballistic coefficient (BC) measures how well a projectile overcomes air resistance. This calculator computes BC from mass, diameter, and drag coefficient for G1, G7, and G5 models with trajectory analysis.

Did our AI summary help? Let us know.

Higher BC = less drop and drift at range G7 BC ~0.5× G1 for same bullet Long-range: prefer G7 BC ≥ 0.25 BC varies with velocity (transonic effects)

Key quantities

BC = m/(Cd×A)

Key relation

SD = m/D²

Sectional Density

Key relation

Cd = 0.515

G1 Model

Key relation

Cd = 0.300

G7 Model

Key relation

Ready to run the numbers?

Why: Higher BC means better velocity retention and less wind drift at long range. G7 is more accurate for modern boat-tail rifle bullets; G1 suits flat-base and pistol rounds.

How: BC = sectional density / form factor. Sectional density SD = m/D². Form factor depends on drag model (G1, G7, G5). BC determines drag force and trajectory.

Higher BC = less drop and drift at rangeG7 BC ~0.5× G1 for same bullet

Sources:Sierra BulletsNIST

Run the calculator when you are ready.

Calculate Ballistic CoefficientEnter bullet mass, diameter, and drag model

🔫 Common Bullet Presets

📐 Calculation Method

⚙️ Input Parameters

Projectile Mass (grains)

Diameter (inches)

Drag Coefficient (Cd)

ballistic-coefficient@bloomberg:~$

COEFFICIENT: MODERATE

bc_analysis.sh

CALCULATED

$ calculate_bc --mass=168gr --diameter=0.308"

BC (G1)

0.434

BC (G7)

0.253

Sectional Density

0.253

Form Factor

0.583

Vel Retention @ 100yd

95.5%

Vel Retention @ 500yd

79.4%

Drag Coefficient

0.300

BC (G5)

0.211

Ballistic Coefficient Analysis

168gr / 0.308"

BC(G1): 0.434

📊 SD: 0.253🎯 G7: 0.253⚡ Vel @ 500yd: 79.4%

numbervibe.com/calculators/physics/ballistic-coefficient-calculator

📈 Visualizations

BC Comparison

Velocity Retention

Drag Model Comparison

Bullet Drop

📝 Step-by-Step Solution

📊 Input Analysis

Projectile Mass: 168.0 grains

Diameter: 0.3080 inches

📐 Sectional Density

SD = (mass / 7000) / diameter²

SD = (168.0 / 7000) / 0.3080²

→ SD = 0.2530

🧮 Ballistic Coefficient Calculation

Drag Coefficient (Cd): 0.300

Form Factor (G1): i = Cd / 0.515

i = 0.300 / 0.515

→ i = 0.5825

BC (G1) = SD / i

BC = 0.2530 / 0.5825

→ BC(G1) = 0.4343

BC (G7) = SD / (Cd / 0.3)

→ BC(G7) = 0.2530

📈 Performance Estimates

Velocity retention at 100 yards: 95.5%

Velocity retention at 500 yards: 79.4%

For educational and informational purposes only. Verify with a qualified professional.

🔬 Physics Facts

🎯

G7 model matches modern 0.5 cal long-range bullets

— Sierra

💨

BC drops in transonic region (Mach 0.8-1.2)

— Applied Ballistics

📐

Sectional density = mass (lb) / diameter (in.)²

— NIST

🔫

Boat-tail design improves form factor vs flat-base

— Berger Bullets

📋 Key Takeaways

• Ballistic Coefficient (BC) measures a projectile's ability to overcome air resistance — higher BC means better velocity retention
• G1 model (Cd = 0.515) is best for flat-base bullets and pistol rounds; G7 model (Cd = 0.300) is more accurate for modern boat-tail rifle bullets
• BC depends on both sectional density (mass per area) and form factor (shape efficiency)
• For long-range shooting (1000+ yards), prioritize bullets with G1 BC ≥ 0.5 or G7 BC ≥ 0.25

💡 Did You Know?

🎯The .50 BMG 750gr A-MAX has a G1 BC of 1.050 — one of the highest BCs ever measured for a production bulletSource: Hornady

📊Bryan Litz's Applied Ballistics testing found that manufacturer BC claims are often 5-15% optimistic compared to real-world measurementsSource: Applied Ballistics

🔬BC varies with velocity, especially in the transonic region (1100-1300 fps) where drag increases dramaticallySource: Ballistic Research Laboratory

🏆The 6.5 Creedmoor became popular for long-range shooting because it achieves BCs of 0.6+ (G1) with moderate recoilSource: Sierra Bullets

🌡️Altitude affects BC — every 1000 feet of elevation increases effective BC by approximately 3% due to lower air densitySource: JBM Ballistics

⚡A bullet with BC 0.5 retains 85% velocity at 500 yards, while BC 0.3 retains only 70% — a huge difference for long-range accuracySource: Berger Bullets

📖 How Ballistic Coefficient Works

Ballistic coefficient quantifies how efficiently a projectile overcomes air resistance compared to a standard reference projectile. It combines sectional density (mass per unit cross-sectional area) with form factor (how streamlined the shape is).

The Formula

BC = \frac{SD}{i} = \frac{\frac{mass}{7000 \times d^2}}{\frac{C_d}{C_{d,ref}}}

Where SD = sectional density, i = form factor, d = diameter, C_d = drag coefficient

Drag Models

• G1: Based on flat-base, blunt-nose projectile (Cd = 0.515) — traditional standard
• G7: Based on boat-tail, tangent ogive projectile (Cd = 0.300) — more accurate for modern bullets
• G5: Lower drag reference (Cd = 0.250) — for very streamlined projectiles

Why BC Matters

Higher BC bullets retain velocity better, resulting in:

• Flatter trajectory (less bullet drop)
• Less wind drift
• More retained energy at long range
• Better accuracy at extreme distances

🎯 Expert Tips for Ballistic Coefficient

💡 Use G7 for Modern Bullets

For boat-tail, VLD, and modern match bullets, G7 BC provides more accurate trajectory predictions than G1, especially beyond 600 yards.

💡 Verify Manufacturer Claims

Independent testing often shows BCs 5-15% lower than advertised. Use Applied Ballistics or JBM data for verified values.

💡 Account for Velocity Changes

BC decreases as velocity drops. Use velocity-specific BC values or ballistic software that accounts for this variation.

💡 Environmental Factors

Higher altitude and temperature increase effective BC by reducing air density. Adjust calculations for shooting conditions.

⚖️ G1 vs G7 Drag Models Comparison

Feature	G1 Model	G7 Model
Reference Shape	Flat-base, blunt nose	Boat-tail, spitzer
Drag Coefficient	Cd = 0.515	Cd = 0.300
Best For	Pistol, flat-base bullets	Modern rifle bullets
Typical BC Range	0.2 - 1.0	0.1 - 0.5
Long-Range Accuracy	Good	Excellent
Industry Standard	Traditional (most common)	Modern (more accurate)
Conversion Factor	G7 ≈ G1 × 0.515	G1 ≈ G7 × 1.94

❓ Frequently Asked Questions

Should I use G1 or G7 ballistic coefficient?

G7 is more accurate for modern boat-tail rifle bullets, especially for long-range shooting. G1 is better for flat-base bullets, pistol rounds, and older bullet designs. Most manufacturers list G1 because it's the traditional standard, but G7 gives better trajectory predictions for modern bullets.

Why does my BC seem to vary with velocity?

BC isn't constant — it changes with velocity because drag coefficient varies with Mach number. This is especially pronounced in the transonic region (around 1100-1300 fps). Some manufacturers publish different BCs for different velocity ranges. G7 modeling handles velocity-dependent drag better than G1.

What's a good BC for long-range shooting?

For serious long-range shooting (1000+ yards), look for G1 BC of 0.5+ or G7 BC of 0.25+. The 6.5 Creedmoor became popular because it achieves high BCs (0.6+ G1) with moderate recoil. Match bullets like Sierra MatchKing and Hornady ELD-M typically have G1 BCs of 0.5-0.7.

How do I convert between G1 and G7 BC?

The rough conversion is G7 ≈ G1 × 0.515, but this varies significantly by bullet shape. For VLD bullets, the factor is closer to 0.50. For accurate conversions, use published values from the manufacturer or test with a chronograph at two distances. Never assume a simple multiplication factor will be accurate.

Does altitude affect ballistic coefficient?

Yes! Higher altitude means lower air density, which reduces drag. Effective BC increases by approximately 3% per 1000 feet of elevation. Temperature also affects air density — hotter air is less dense, increasing effective BC by about 1% per 20°F increase.

Why are manufacturer BC claims often optimistic?

Manufacturers typically measure BC at high velocities in ideal conditions. Real-world testing by Bryan Litz (Applied Ballistics) and others shows BCs are often 5-15% lower than advertised. Independent verification is recommended for precision shooting.

What's the difference between sectional density and ballistic coefficient?

Sectional density (SD) is mass per unit cross-sectional area — it measures penetration potential. Ballistic coefficient (BC) equals SD divided by form factor — it measures aerodynamic efficiency. A bullet can have high SD but low BC if it has poor shape (high form factor).

How does bullet shape affect BC?

Streamlined shapes dramatically improve BC: boat-tail bases reduce base drag, sharp ogive noses reduce pressure drag, and smooth surfaces reduce skin friction. A VLD (Very Low Drag) bullet design can achieve BCs 30-50% higher than a flat-base bullet of the same weight and caliber.

📊 Ballistic Coefficient by the Numbers

0.5+

High BC (G1)

0.3-0.5

Medium BC

<0.3

Low BC

BC gain/1000ft

📚 Official Data Sources

Applied Ballistics - Bryan Litz ↗

Comprehensive BC testing and ballistic data

Updated: 2026-01-15

Sierra Bullets BC Database ↗

Official Sierra MatchKing BC values

Updated: 2026-02-01

Hornady Ballistic Coefficient Tables ↗

ELD-M and ELD-X BC specifications

Updated: 2026-01-20

Berger Bullets BC Data ↗

VLD and hybrid BC measurements

Updated: 2026-01-25

JBM Ballistics Calculator ↗

Online BC calculator and drag model reference

Updated: 2026-02-05

Ballistic Research Laboratory ↗

Original G1, G5, G7 drag function definitions

Updated: 1950-01-01

⚠️ Disclaimer: This calculator provides estimates based on standard ballistic models and published data. Actual BC values vary with velocity, environmental conditions, and individual bullet manufacturing variations. For precision shooting, verify BC with chronograph testing at multiple distances. Always follow firearm safety rules and local regulations. Not responsible for shooting accuracy or safety.

👈 START HERE

⬅️Jump in and explore the concept!

Ballistic Coefficient - Projectile Air Resistance

🔫 Common Bullet Presets

📐 Calculation Method

⚙️ Input Parameters

📈 Visualizations

BC Comparison

Velocity Retention

Drag Model Comparison

Bullet Drop

📝 Step-by-Step Solution

🔬 Physics Facts

📋 Key Takeaways

💡 Did You Know?

📖 How Ballistic Coefficient Works

The Formula

Drag Models

Why BC Matters

🎯 Expert Tips for Ballistic Coefficient

💡 Use G7 for Modern Bullets

💡 Verify Manufacturer Claims

💡 Account for Velocity Changes

💡 Environmental Factors

⚖️ G1 vs G7 Drag Models Comparison

❓ Frequently Asked Questions

Should I use G1 or G7 ballistic coefficient?

Why does my BC seem to vary with velocity?

What's a good BC for long-range shooting?

How do I convert between G1 and G7 BC?

Does altitude affect ballistic coefficient?

Why are manufacturer BC claims often optimistic?

What's the difference between sectional density and ballistic coefficient?

How does bullet shape affect BC?

📊 Ballistic Coefficient by the Numbers

📚 Official Data Sources

Related Physics Calculators

Related Calculators

Maximum Height Calculator

Muzzle Velocity Calculator

Momentum Calculator

Conservation of Momentum Calculator

Displacement Calculator

Friction Calculator

We Value Your Privacy