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Conversor de unidades CSS (px a rem, em, pt)

Convierta px a rem, em, pt, picas, pulgadas y mm usando el tamaño de fuente raíz, el del elemento padre y los DPI. CSS establece 1 in = 96 px = 72 pt.

Actualizado Ejemplos verificados: 7

px
Más opciones
px
DPI
CSS fixes 1 in = 96 px. Enter a screen or printer density (e.g. 300) to count physical pixels instead.
Probar
Valor convertido
rem
Valor convertido: 1.5 rem
Cifras significativas: 10; Al más cercano; empates alejándose de cero
As CSS
1.5rem
In pixels
24px

24px is 1.5rem with a 16 px root font and 96 pixels per inch.

Size in pixels next to the font sizes

24px24 px1 rem (root)16 px1 em (parent)16 px
24px in every unit Filas: 10
UnidadValorDefinición
Pixels (px)24px1 px
Points (pt)18pt1 pt = 1/72 in
Picas (pc)1.5pc1 pc = 12 pt = 1/6 in
Inches (in)0.25in1 in = DPI px
Centimetres (cm)0.635cm1 cm = 1/2.54 in
Millimetres (mm)6.35mm1 mm = 1/25.4 in
Quarter-millimetres (Q)25.4Q1 Q = 0.25 mm
em (parent font size)1.5em1 em = parent font size
rem (root font size)1.5rem1 rem = root font size
Percent of parent font size (%)150%100% = parent font size
Cómo se calcula S

  1. Pixels in one px

    1 px=1 px1\,\text{px} = 1\ \text{px}

    1 px

  2. Value in pixels

    24×1=24 px24 \times 1 = 24\ \text{px}

  3. Divide by pixels in one rem

    2416=1.5 rem\frac{24}{16} = 1.5\ \text{rem}

    1 rem = root font size

Acerca de Conversor de unidades CSS (px a rem, em, pt)

CSS converts every length through pixels. The absolute units are fixed to each other: 1 in = 2.54 cm = 96 px = 72 pt = 6 pc, and 1 Q is a quarter of a millimetre. The font-relative units depend on the page: 1 rem is the root element's font size, and when you set font-size, 1 em (or 100%) is the parent's font size. The converter turns the value into pixels, then divides by the pixels in one target unit.

Front-end developers use it to turn a design's pixel sizes into rem, so text follows the reader's browser font setting: with the default 16 px root, 24 px is 1.5 rem. Print designers use the pixels-per-inch field instead; at 300 DPI a 10 mm logo needs about 118 pixels.

On screens a CSS inch is not a measured inch. Browsers anchor 96 px to a reference pixel of about 0.0213° of visual angle, so physical units match a ruler only in print.

Ejemplos resueltos

24 px in rem

Valor
24
De
Pixels (px)
A
rem (root font size)
Root font size (for rem)
16 px
Valor convertido
1.5 rem
As CSS
1.5rem
In pixels
24 px

Fuente de comprobación: CSS Values 3 §6.1: 1rem = root font size (16 px browser default); 24 / 16 = 1.5

12 pt in px

Valor
12
De
Points (pt)
A
Pixels (px)
Root font size (for rem)
16 px
Valor convertido
16 px
As CSS
16px

Fuente de comprobación: CSS Values 3 §6.2: 1pt = 1/72 in, 1in = 96px; 12 × 96/72 = 16

1 inch in CSS pixels

Valor
1
De
Pulgadas (in)
A
Pixels (px)
Root font size (for rem)
16 px
Valor convertido
96 px

Fuente de comprobación: CSS Values 3 §6.2: 1in = 96px

1.5 rem in px

Valor
1.5
De
rem (root font size)
A
Pixels (px)
Root font size (for rem)
16 px
Valor convertido
24 px

Fuente de comprobación: 1 rem = root font size (16 px); 1.5 × 16

Preguntas

How many pixels is 1 rem?

16 pixels by default. One rem equals the font size of the root html element, and the major browsers set that to 16 px unless the reader changes the default font size or the stylesheet sets html { font-size }. Setting html { font-size: 62.5% } makes 1 rem = 10 px. The W3C CSS Values and Units specification defines rem; the 16 px figure is the browser default, not part of the specification.

How do I convert px to pt?

Multiply pixels by 0.75; to go from points to pixels, multiply by 4/3 (about 1.333). Both factors follow from the W3C CSS rule 1 in = 96 px = 72 pt, so 1 px = 72/96 pt. Body text at 16 px is 12 pt, and 11 pt text from a word processor is about 14.67 px.

What is the difference between em and rem?

rem always refers to the root element's font size; em refers to the current element's font size, or to the parent's when used on font-size itself. So em compounds when nested: a list set to 1.2em inside another list set to 1.2em has text 1.44 times the outer size, while 1.2rem stays at 19.2 px with a 16 px root however deep it sits.

Should I use px or rem for font sizes?

Use rem if text should follow the reader's browser font-size setting. Page zoom enlarges px and rem alike, but the default font-size preference changes only rem, em and percentage sizes. WCAG 2.1 success criterion 1.4.4 (level AA) requires text that can be resized to 200% without loss of content or function; browser zoom can meet it with px, and rem also honours the font-size preference.

Is a CSS inch the same as a real inch?

Only in print. CSS defines 1 in as exactly 96 px, and on screens browsers anchor the pixel to the W3C reference pixel: one pixel of a 96 DPI screen seen from 28 in away, a visual angle of about 0.0213°. Phones are held closer and use smaller pixels, so a 96 px box measures well under an inch on most phones. Printers anchor to physical units, so 1 in prints as 25.4 mm.

¿Qué precisión tiene «Conversor de unidades CSS (px a rem, em, pt)»?

La precisión depende de tus datos y de los supuestos del método. El cálculo decimal usa 50 cifras significativas, pero las estimaciones, los métodos numéricos y los datos de origen pueden ser menos precisos; el redondeo mostrado no elimina esos límites. Ejemplos resueltos comprobados con fuentes independientes: 7. Por ejemplo, «24 px in rem» se comprueba con CSS Values 3 §6.1: 1rem = root font size (16 px browser default); 24 / 16 = 1.5.

¿De dónde procede el método?

W3C — CSS Values and Units Module Level 3, §6.2 absolute lengths and §6.1 font-relative lengths.

Acerca de esta calculadora

to=value×px per from-unitpx per to-unit1 in=96 px=72 pt=2.54 cm\begin{gathered} \text{to} = \text{value} \times \frac{\text{px per from-unit}}{\text{px per to-unit}} \\ 1\,\text{in} = 96\,\text{px} = 72\,\text{pt} = 2.54\,\text{cm} \end{gathered}

Fuentes

  1. W3C — CSS Values and Units Module Level 3, §6.2 absolute lengths and §6.1 font-relative lengths

Verificado con las referencias

Esta calculadora incluye 7 ejemplos resueltos con respuestas de fuentes independientes. Forman parte del conjunto de pruebas y también puedes ejecutarlos aquí.

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