Quadratic Drag Terminal Speed Calculator
Calculate a model terminal falling speed from weight and constant quadratic drag.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Equate weight with the stated quadratic drag force and solve for positive terminal speed.
mg=½ρCdAv²; vt=√[2mg/(ρCdA)]
Worked example
Mass1kg, density1.225kg/m³, projected area0.1m², Cd=1 and g=9.80665m/s² give terminal speed≈12.6534016m/s.
Assumptions and input details
Mass, fluid density, projected area, Cd and gravity must be positive. Assume constant density/Cd/area and neglect buoyancy, lift, wind, compressibility and changing orientation. Cd must correspond to the entered projected reference area and relevant flow regime; no lookup is made. This is a steady force balance, not fall time, required fall distance, impact speed or a safety assessment.
References: NASA: drag and terminal velocity
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
The 19 mass definitions distinguish avoirdupois and troy measures, metric and regional measures. Japanese kin is 600 g; mainland Chinese shijin is 500 g.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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