CSS Unit Converter - px, em, rem, vw Calculator

Convert between CSS units: px, em, rem, vw, vh, pt, cm, mm. Set base font size for accurate conversion. Client-side processing.

Base font size (root)

Viewport width

Viewport height

Input Value

Unit

Converted Values

Pixels

16 px

REM

1 rem

1 em

0.83 vw

1.48 vh

Points

12 pt

Centimeters

0.42 cm

Inches

0.17 in

Common Conversions

px	rem	pt	Use Case
10	0.625	7.5	Small text, captions
12	0.75	9	Body text (small)
14	0.875	10.5	Body text (medium)
16	1	12	Body text (default)
18	1.125	13.5	Large body text
20	1.25	15	H4, subheadings
24	1.5	18	H3 headings
32	2	24	H2 headings
48	3	36	H1 headings

PX to REM Converter - CSS Unit Conversio…

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Frequently Asked Questions

em is relative to the parent element's font size, while rem is relative to the root (html) element's font size. rem is more predictable for consistent sizing.

Divide pixels by the base font size (usually 16px). So 24px = 24/16 = 1.5rem.

vw is 1% of viewport width, vh is 1% of viewport height. They're useful for responsive designs that scale with screen size.

Points (pt) are mainly for print stylesheets. 1pt = 1/72 inch. Use px or rem for screen.

Relative units (rem, em, %) scale with user preferences and screen size, improving accessibility. Users who increase font size see properly scaled layouts.

Mix units: rem for typography and spacing, % or vw/vh for layout widths, px for fixed elements like borders. This creates flexible, accessible designs.

vmin uses the smaller of viewport width or height. vmax uses the larger. Useful for ensuring elements fit on any orientation. Not shown in this tool but available in CSS.

rem is generally safer—it ensures consistent spacing regardless of nesting. em can cause compounding issues when elements nest deeply.

16px is the standard default. Users can change this in browser settings. Use rem to respect user preferences rather than forcing pixel sizes.

They're based on CSS's definition of 96 DPI, not actual screen DPI. A CSS 'inch' isn't a real inch on screen. These units are mainly for print stylesheets.

Converted Values

Common Conversions

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