Bullet Stopping Power Physics Calculator

Compare bullet energy, momentum, force, and indexes quickly. Use educational physics, not real damage claims. Export clear results for records after each calculation session.

Calculator Input

This tool compares measurable bullet physics values. It is for education, reporting, and controlled data review only.

Example Data Table

Example Mass Velocity Diameter Expanded Diameter Depth Transfer
Demo A 124 grains 1150 ft/s 0.355 in 0.55 in 12 in 80%
Demo B 180 grains 980 ft/s 0.400 in 0.62 in 14 in 75%
Demo C 55 grains 2600 ft/s 0.224 in 0.30 in 10 in 60%

Formula Used

Kinetic energy: KE = 0.5 × m × v²

Momentum: p = m × v

Transferred energy: Etransfer = KE × transfer percent

Average stopping force: Favg = Etransfer ÷ stopping distance

Average deceleration: a = Favg ÷ m

Ideal stop time: t = 2 × stopping distance ÷ impact velocity

Sectional density: SD = bullet weight in pounds ÷ diameter² in inches

Frontal area: A = π × radius²

Energy density: Earea = transferred energy ÷ expanded frontal area

Taylor comparison index: TKO = grains × ft/s × diameter inches ÷ 7000

Stopping power is not a single accepted physics formula. These outputs are comparison values only.

How To Use This Calculator

  1. Enter bullet mass and choose the correct mass unit.
  2. Enter measured velocity and choose its unit.
  3. Add estimated velocity loss when using a starting velocity.
  4. Enter original bullet diameter.
  5. Add expanded or effective diameter when known.
  6. Enter stopping distance or controlled penetration depth.
  7. Set estimated energy transfer percentage.
  8. Enter impact angle if the path is not straight.
  9. Press calculate and review the result above the form.
  10. Use CSV or PDF buttons to save the result.

Educational Physics Behind Bullet Stopping Power

Measurable Values

Bullet stopping power is a common phrase, yet it has no single accepted scientific value. Real effects depend on many conditions. These include projectile shape, construction, speed, angle, tissue model, distance, and measurement method. This calculator keeps the topic inside measurable physics.

Energy And Momentum

Energy and momentum show different things. Kinetic energy grows with the square of speed. A small velocity change can change energy strongly. Momentum grows in direct proportion to speed. It describes impulse and resistance to slowing. Both values matter, but neither value alone proves real stopping ability.

Stopping Force

The tool also estimates average stopping force. It divides transferred energy by stopping distance. This assumes a smooth stop and uniform deceleration. Real projectiles do not stop that neatly. They yaw, deform, fragment, or pass through. Because of this, the value is best used for classroom comparison or controlled test notes.

Area And Density

Sectional density compares mass with bullet diameter. A higher value usually means more mass behind each unit of frontal diameter. Frontal area and expanded area show how the diameter changes the contact surface. Energy density then divides energy by area. It can help compare two examples with different sizes.

Historical Index

The Taylor index is included only as a historical comparison number. It is not a modern injury predictor. It uses bullet weight, speed, and diameter. Treat it as a simple reference index, not as proof of performance.

Safe Study Use

Use safe sample data when learning. You can enter laboratory values, manufacturer numbers, or fictional examples. Avoid using the output to choose weapons or ammunition. The calculator does not advise on real use. It does not replace professional testing, legal guidance, or safety training.

Practical Workflow

A useful workflow is simple. Enter mass first. Choose the correct mass unit. Add measured velocity next. Enter diameter and optional expansion diameter. Add penetration depth only when it comes from a controlled test. Review each result line. Export the table when you need records for a report, lesson, or comparison sheet.

When comparing entries, change one input at a time. This makes patterns easier to see and keeps reports fair, repeatable, and easier to explain later.

FAQs

Is stopping power a fixed physics value?

No. Stopping power is not one accepted scientific number. It depends on energy, momentum, bullet design, medium, distance, impact angle, and test conditions.

What is the most important output?

Kinetic energy and momentum are both important. Energy changes quickly with speed. Momentum shows impulse. Average force needs a reliable stopping distance.

Does this calculator predict injury?

No. It only calculates physics values. It does not predict injury, lethality, medical outcome, or real stopping ability.

Why is penetration depth needed?

Average stopping force needs distance. The calculator divides transferred energy by the stopping depth to estimate ideal average force.

What does energy transfer percent mean?

It is the estimated share of kinetic energy deposited during stopping. Use controlled test data when available. Otherwise, treat it as a comparison assumption.

What is sectional density?

Sectional density compares projectile mass with diameter. It is weight in pounds divided by diameter squared in inches.

Why include the Taylor index?

It is a historical comparison index using bullet weight, speed, and diameter. It is not a modern damage or safety predictor.

Can I export the calculation?

Yes. After calculation, use the CSV or PDF button below the result table to save the output.


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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.