How to use the ballistic coefficient calculator
Prepare the values for this calculation
Calculate the general aerodynamic ballistic coefficient from object mass, drag coefficient and the matching aerodynamic reference area. This is an aerospace/drag parameter, not an ammunition-specific G1/G7 trajectory model. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Input unit system: choose SI: kg and m², US customary: lbm and ft². Match this selection to the data you enter.
- Object mass: enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Drag coefficient C_D: enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
- Reference area: enter a value at least 0. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Aerodynamic ballistic coefficient first. With the unchanged example inputs, it is 50 kg/m². Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Object mass from 1000 to 1100. The resulting Aerodynamic ballistic coefficient is 55 kg/m². This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Ballistic Coefficient Calculator formula
β = m ÷ (C_D × A), where m is mass, C_D is the dimensionless drag coefficient, and A is the same reference area used to define C_D.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Input unit system | Select an option | SI: kg and m² |
| Object mass | minimum 0 | 1000 |
| Drag coefficient C_D | minimum 0 | 2 |
| Reference area | minimum 0 | 10 |
Worked example
Using the example inputs above, the aerodynamic ballistic coefficient is 50 kg/m².
- Aerodynamic ballistic coefficient
- 50 kg/m²
- SI ballistic coefficient
- 50 kg/m²
- US customary ballistic coefficient
- 10.240807 lbm/ft²
- Drag coefficient used
- 2
Results and assumptions
General aerodynamic definition β=m/(C_DA). The drag coefficient and reference area must use the same aerodynamic convention; C_D can vary with speed, orientation, Reynolds/Mach regime and other flow conditions. This calculator does not implement ammunition-specific G1/G7 drag standards or trajectory prediction.
Sources and method references
Fix an input or unexpected result
Object mass is required. Enter object mass using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.