Typography Units & CSS Font Size Converter (pt, px, em, rem

Typography Metrology, Points, Pixels, REM & PostScript Systems

Typography measurement bridges physical print geometry and digital raster displays. The modern global standard is defined by the PostScript DTP point and the W3C CSS reference pixel:

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• Universal Typography Conversion Formulas (W3C & PostScript)**:

$$1\text{ Inch (in)} = 96\text{ CSS Pixels (px)} = 72\text{ Points (pt)} = 6\text{ Picas (pc)} = 25.4\text{ mm} = 1,440\text{ Twips}$$

$$1\text{ Point (pt)} = \frac{96}{72}\text{ px} = 1.333333\text{ px} = \frac{1}{12}\text{ pc} \approx 0.352778\text{ mm} = 20\text{ Twips}$$

$$1\text{ CSS Pixel (px)} = \frac{72}{96}\text{ pt} = 0.75\text{ pt} = \frac{1}{16}\text{ pc (at 16px base)} \approx 0.264583\text{ mm}$$

$$1\text{ rem} = \frac{\text{Font Size in px}}{\text{Root Font Size in px (default 16px)}} \quad | \quad 1\text{ Pica (pc)} = 12\text{ pt} = 16\text{ px}$$

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• Historical Point Standards**:

• DTP / PostScript Point: Exactly $1/72\text{ in} = 0.352778\text{ mm}$ (Global computing standard)

• Didot Point (European): $\approx 0.376065\text{ mm} = 1/72\text{ of French Pied}$

• Fournier / Traditional American Point: $\approx 0.35146\text{ mm} = 0.013837\text{ in}$

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• Standard Digital & Print Typography Hierarchy**:

• Legal Fine Print / Footnote: $\mathbf{8.0\text{ pt}} = 10.67\text{ px} = 0.667\text{ rem} = 2.822\text{ mm}$

• Book / Magazine Body Text: $\mathbf{10.0\text{ pt}} = 13.33\text{ px} = 0.833\text{ rem} = 3.528\text{ mm}$

• Default Web Body Copy: $\mathbf{12.0\text{ pt}} = 16.00\text{ px} = 1.000\text{ rem} = 1.000\text{ pc}$

• H2 Section Subheading: $\mathbf{18.0\text{ pt}} = 24.00\text{ px} = 1.500\text{ rem} = 1.500\text{ pc}$

• H1 Hero Headline: $\mathbf{24.0\text{ pt}} = 32.00\text{ px} = 2.000\text{ rem} = 2.000\text{ pc}$