Cross Arm Width Proportion Calculator
Cross arm widths use their respective perpendicular envelope dimensions, not one width denominator for both.
Description
Vertical and horizontal cross arms use different field dimensions as their width bases.
Vertical and horizontal cross arms use different field dimensions as their width bases.1
Keeping those two fractions separate avoids mixing width and height proportions.
When to use Cross Arm Width Proportion Calculator
Use this tool to calculate or review the supplied observations under the stated rules. Establish the source tradition, viewing frame, coordinate units and independently annotated features.
How to use Cross Arm Width Proportion Calculator and understand its results
- Establish the source tradition, viewing frame, coordinate units and independently annotated features.
- Enter fieldWidth, fieldHeight, verticalArmWidth, horizontalArmWidth, using the field meanings and rules below, then run the tool.
- Read result.verticalArmFraction, result.horizontalArmFraction, using the output meanings and calculation rules below.
- Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| fieldWidth | Field width | number | Required |
| fieldHeight | Field height | number | Required |
| verticalArmWidth | Vertical arm width | number | Required |
| horizontalArmWidth | Horizontal arm width | number | Required |
Use positive field width and height and positive vertical and horizontal arm widths. Require vertical-arm width≤field width and horizontal-arm width≤field height. Return the vertical width divided by field width and horizontal width divided by field height separately.
verticalFraction=verticalArmWidth/fieldWidth; horizontalFraction=horizontalArmWidth/fieldHeight Use the matching field units and the exact boundary, ordering and reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Calculated observation or reference | object |
| result.verticalArmFraction | vertical Arm Fraction; dimensionless fraction, not a percent | number |
| result.horizontalArmFraction | horizontal Arm Fraction; dimensionless fraction, not a percent | number |
{
"input": {
"fieldWidth": 100,
"fieldHeight": 120,
"verticalArmWidth": 20,
"horizontalArmWidth": 24
},
"output": {
"result": {
"verticalArmFraction": 0.2,
"horizontalArmFraction": 0.2
}
}
}Limitations and assumptions
Measurements must share a unit. The tool does not enforce a preferred cross proportion, model the intersection or fit a shield outline.
Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Extremely large composite outputs are rejected.
Alternative or Complementary methods
For a related step, use Ordinary Width Proportion Checker (chief/fess/pale/bend): Ordinary-width review depends on the selected drawing and proportion standard. For a complementary comparison, use Escutcheon of Pretence Size Proportion Calculator: An inescutcheon's width can be compared with the outer shield's width.
References
-
Cross Arm Width Proportion Calculator — tool.io
Similar or alternative tools
- Ordinary Width Proportion Checker (chief/fess/pale/bend)
Ordinary-width review depends on the selected drawing and proportion standard.
- Escutcheon of Pretence Size Proportion Calculator
An inescutcheon's width can be compared with the outer shield's width.