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Centre of Mass

Upload a photo, click each body landmark, and compute the whole-body centre of mass using segmental analysis. A teaching tool for biomechanics - everything runs locally in your browser.
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How it works

Click 17 body landmarks on a photograph (top of head → toes). The tool draws body segments, calculates each segment's centre of mass using published anthropometric data (de Leva, 1996), and combines them into a single whole-body CoM position.

  • Male / Female segment parameters are selectable
  • Zoom lens follows your cursor for precise clicking
  • Undo / Reset if you mis-click
  • Download the annotated image with segments and CoM marker
1
Load image and set options
Everything runs locally in the browser.
2
Click landmarks (top → bottom)
Click each landmark once - segments reuse joints automatically.

What to do next

Upload an image to begin.
Tip: click the centre of each joint/marker.
Progress
0 / 0
Whole-body CoM (x, y)
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Segments draw in green when both endpoints are available. Whole-body CoM appears as a yellow circle with a red outline when complete. Hover the image to use the zoom lens.
3
Download annotated image
Includes segment lines and the CoM marker.
Available once the whole-body CoM has been computed.
View tables (joints, segments, segment CoM)
Use these tables to check coordinates and segment calculations.

Joint clicks

OrderJointXY

Segments + segment CoM

SegmentProxDistalProx (x,y)Distal (x,y)Len %Mass %Seg CoM (x,y)
References

Segment parameters: de Leva, P. (1996). Adjustments to Zatsiorsky-Seluyanov's segment inertia parameters. Journal of Biomechanics, 29(9), 1223-1230. https://doi.org/10.1016/0021-9290(95)00178-6

Original cadaver data: Dempster, W.T. (1955). Space requirements of the seated operator. WADC Technical Report 55-159. Wright-Patterson Air Force Base, Ohio.

Zatsiorsky data: Zatsiorsky, V., & Seluyanov, V. (1983). The mass and inertia characteristics of the main segments of the human body. In H. Matsui & K. Kobayashi (Eds.), Biomechanics VIII-B (pp. 1152-1159). Human Kinetics.

General reference: Winter, D.A. (2009). Biomechanics and Motor Control of Human Movement (4th ed.). Wiley.

biomex.studio© 2026 Andrew Callaway