Angle of Impact Calculator

Find the impact angle of a blood spatter stain.

Stain width

Stain length

Impact angle (deg) 30

Formula: angle = arcsin(width / length)

Step-by-step with your numbers:

1. Values used:

2. Stain width = 4

3. Stain length = 8

5. Impact angle = 30deg

Did we solve your problem today?

Bloodstain analysts find the impact angle from a drop's width-to-length ratio.

The math behind it

A drop hitting at an angle stretches into an ellipse: sin(angle) = width / length.

A 4 mm by 8 mm stain hit at about 30 degrees.

What does 90 degrees look like?

A perpendicular hit makes a near-circular stain (width equals length).