Description
Convert both to points and return reciprocal type-size/leading ratios.
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.
Convert both to points and return reciprocal type-size/leading ratios.
When to use this tool
Use Type Size Leading Ratio 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 typeSize, measuredLeading, typeUnitInPoints, leadingUnitInPoints. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read typeSizePerLeading, leadingPerTypeSize. Use the output convention below.
Require positive typeSize, measuredLeading, and their respective unit-in-points factors. Convert both to points and return reciprocal type-size/leading ratios.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| typeSize | Type Size | Required. Finite number; strictly above 0. |
| measuredLeading | Measured Leading | Required. Finite number; strictly above 0. |
| typeUnitInPoints | Type Unit In Points | Required. Finite number; strictly above 0. |
| leadingUnitInPoints | Leading Unit In Points | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| typeSizePerLeading | Type Size Per Leading | Required. Finite number. |
| leadingPerTypeSize | Leading Per Type Size | Required. Finite number. |
{
"input": {
"typeSize": 12,
"measuredLeading": 18,
"typeUnitInPoints": 1,
"leadingUnitInPoints": 1
},
"output": {
"typeSizePerLeading": 0.6666666666666666,
"leadingPerTypeSize": 1.5
}
}Limitations and assumptions
- Leading denotes the supplied line-to-line measure in this calculation; ratios do not establish readability, font metrics, or a recommended typographic setting.
- 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
- Type Cap Height Xheight Ratio
Return xHeight/capHeight and scale both design-unit heights by fontPixels/unitsPerEm.
- Type Capheight Lineheight Share
Return cap/line share, ascender+descender occupiedHeight, and lineHeight minus that total.