Calculator Inputs
Enter limb length and best reach values for each tested direction. Results appear above this form after submission.
Plotly Graph
The chart compares normalized directional reach percentages and composite scores for both sides.
Example Data Table
| Side | Limb Length | Anterior | Posteromedial | Posterolateral | Composite Score |
|---|---|---|---|---|---|
| Left | 90 cm | 68 cm | 96 cm | 94 cm | 95.56% |
| Right | 91 cm | 70 cm | 97 cm | 93 cm | 95.24% |
Formula Used
Composite Score = ((Anterior + Posteromedial + Posterolateral) ÷ (3 × Limb Length)) × 100
Normalized Reach = (Reach Distance ÷ Limb Length) × 100
Asymmetry = |Left Reach − Right Reach|
The calculator normalizes each reach value by limb length, then averages the three directions into a composite percentage for each side. It also compares left and right side reach distances and highlights asymmetry against your chosen threshold.
How to Use This Calculator
- Measure limb length for the left and right side using the same unit.
- Record the best anterior, posteromedial, and posterolateral reach distances for each side.
- Set the asymmetry threshold and target composite score that fit your assessment rule.
- Click Calculate Score to display results above the form.
- Review composite scores, normalized reaches, differences, warning flags, and the graph.
- Download the output as CSV or PDF if you need a report.
Frequently Asked Questions
1) What does the y balance composite score show?
It summarizes reach performance across three directions for one limb. Because it is normalized by limb length, it helps compare movement quality more fairly between different people or between left and right sides.
2) Why normalize reach by limb length?
A longer limb can naturally produce longer raw reach distances. Normalizing by limb length converts raw measurements into percentages, making comparisons more useful and reducing size-related bias.
3) What is a good composite score?
Many practitioners treat higher percentages as better, but acceptable values depend on the purpose of testing. This calculator uses a customizable target so you can apply your own screening standard or program benchmark.
4) What does asymmetry mean here?
Asymmetry is the absolute difference between left and right reach distances in the same direction. A larger difference may suggest a side-to-side imbalance worth reviewing in training or assessment.
5) Can I use inches instead of centimeters?
Yes. Use the same unit consistently for limb length and all reach values. The normalized and composite percentages stay valid because the formula uses ratios, not fixed units.
6) Is this calculator only for athletes?
No. It can also support rehabilitation planning, general movement screening, or career planning for physically demanding roles where balance, reach control, and side-to-side quality matter.
7) Should one test decide readiness alone?
No. The result is best used with strength, pain status, job demands, coaching observation, and professional judgment. One score should support decisions, not replace a full evaluation.
8) What should I do if one direction is much lower?
Review technique first, then consider mobility, stability, and strength factors linked to that direction. Re-test consistently after practice or training changes to confirm whether the difference remains meaningful.