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Calcimator

Blood Spatter Analysis Calculator

Calculate bloodstain impact angle, area of origin, and droplet velocity from stain dimensions. Uses the sine-ratio method for angle determination.

Inputs

mm
mm
ft

Results

Impact Angle

24.6°

Area of Origin Height

1.83 ft

≈ 6 credit cards

Estimated Velocity5.32 m/s
Spatter ClassificationMedium Velocity (blunt force)
How to Use This Calculator
  1. Enter Stain Width, Stain Length, and Distance from Origin.
  2. Review Impact Angle (°) and Area of Origin Height (ft).
  3. Use Estimated Velocity (m/s) and Spatter Classification to inform your decision.
  4. Use the chart to visualize the results and explore different scenarios by adjusting inputs.

How the result changes with Stain Width

Stain WidthImpact AngleArea of Origin Height
5.4527°2.04 ft
1890°65,324,957,412,781,470 ft
3390°65,324,957,412,781,470 ft
4590°65,324,957,412,781,470 ft

What each input means

Stain Width
Narrowest dimension of the elliptical bloodstain.
Stain Length
Longest dimension of the elliptical bloodstain (includes any tail).
Distance from Origin
Horizontal distance from the stain to the estimated area of convergence.

What each result means

Impact Angle
Angle at which the droplet struck the surface (arcsin of width/length).
Area of Origin Height
Estimated height of the blood source above the surface.
Estimated Velocity
Approximate droplet velocity from stain size.
Spatter Classification
Low, medium, or high velocity classification.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Stain Width = 5, Stain Length = 12, Distance from Origin = 4 = 3 input(s) provided
  2. Calculate Impact Angle
    Impact Angle
    24.6 = 24.6
  3. Calculate Area of Origin Height
    Area of Origin Height
    1.83 = 1.83
  4. Calculate Estimated Velocity
    Estimated Velocity
    5.32 = 5.32

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