Description
Subtract suppliedDefault from axisValue and divide by positive suppliedScale for normalizedOffset.
Typography combines several distinct scales: font size describes an em scale, cap height describes a font metric, leading describes baseline spacing, and variable-font axes select design coordinates. Ratios between them require an explicit convention.
Subtract suppliedDefault from axisValue and divide by positive suppliedScale for normalizedOffset.
When to use this tool
Use Font Axis Default Reference Offset when you need to compare supplied type metrics or font-axis values on a consistent basis.
How to use the tool and how it works
- Enter axisValue, suppliedDefault, suppliedScale. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read offset, normalizedOffset. Use the output convention below.
Subtract suppliedDefault from axisValue and divide by positive suppliedScale for normalizedOffset.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| axisValue | Axis Value | Required. Finite number. |
| suppliedDefault | Supplied Default | Required. Finite number. |
| suppliedScale | Supplied Scale | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| offset | Signed displacement or phase under the convention above. | Required. Finite number. |
| normalizedOffset | Normalized Offset | Required. Finite number. |
{
"input": {
"axisValue": 500,
"suppliedDefault": 400,
"suppliedScale": 100
},
"output": {
"offset": 100,
"normalizedOffset": 1
}
}Limitations and assumptions
- This is a supplied symmetric linear normalization without axis bounds, OpenType default-side scaling, avar mapping, or font inspection.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Read actual font metrics and variation tables when available, then proof the text in its intended renderer. A metric calculation cannot replace shaping, glyph inspection, or an actual layout test.
References
Similar or alternative tools
- Variable Font Namedinstance Axis Gap
Return current-namedValue and normalize each side of the default separately into [-1, 1], with default mapped to zero.
- Variable Font Optical Size Reference Pair Tool
Compare an explicit variable-font optical-size axis coordinate with a supplied reference without selecting font-specific bounds.