Angle of Impact Calculator
Calculate the angle of impact for blood spatter analysis in forensic investigations
Calculate Angle of Impact
Shortest diameter of the blood spatter ellipse
Longest diameter of the blood spatter ellipse
Impact Analysis Results
Example Calculations
Case Study 1: High Impact Angle
Spatter measurements: Width = 2.1 cm, Length = 2.3 cm
Calculation: α = arcsin(2.1/2.3) = arcsin(0.913) = 65.9°
Analysis: Nearly perpendicular impact, victim likely standing or sitting
Height at 33 cm distance: ~74 cm from ground
Case Study 2: Medium Impact Angle
Spatter measurements: Width = 1.4 cm, Length = 1.7 cm
Calculation: α = arcsin(1.4/1.7) = arcsin(0.824) = 55.4°
Analysis: Moderate angle, medium elongation
Height at 52 cm distance: ~75 cm from ground
Case Study 3: Low Impact Angle
Spatter measurements: Width = 1.9 cm, Length = 3.1 cm
Calculation: α = arcsin(1.9/3.1) = arcsin(0.613) = 37.8°
Analysis: Shallow angle, highly elongated spatter
Height at 98 cm distance: ~76 cm from ground
Forensic Analysis Steps
Measure Spatter
Measure width and length of blood droplet
Calculate Angle
Apply arcsin formula to find impact angle
Reconstruct Scene
Use angle and distance to find origin height
String Analysis
Combine multiple spatters to find convergence
Measurement Guidelines
Ignore tails and irregular edges in measurements
Measure the main elliptical body of the spatter
Use consistent units across all measurements
Width should never exceed length
Photograph spatters before measuring
Understanding Blood Spatter Analysis
What is Angle of Impact?
The angle of impact is the acute angle between the trajectory of a blood droplet and the surface it strikes. This angle directly affects the shape of the resulting blood spatter, making it a crucial parameter in forensic blood pattern analysis.
Forensic Applications
- •Reconstruct crime scene dynamics
- •Determine position of victim and assailant
- •Estimate height of blood source
- •Verify or contradict witness statements
Mathematical Foundation
α = arcsin(W/L)
- α: Angle of impact (degrees)
- W: Width of spatter (minor axis)
- L: Length of spatter (major axis)
- arcsin: Inverse sine function
Important: This formula assumes ideal conditions. Real-world factors like surface texture, blood viscosity, and air resistance can affect accuracy.