REM to PX Converter
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Convert rem ↔ px using root font size — default 16 px browser standard.
Root font size
Pixels
24 px
1.5 rem @ 16 px root
- Formula
- 1.5 × 16
Related calculators
REM and pixels
CSS rem units are relative to the root element font size — usually 16 px in browsers. 1.5 rem = 24 px when root is 16 px. rem scales with user accessibility settings that change root font size; px is absolute.
Design handoffs often use px; production CSS may prefer rem for accessibility. Convert at the project's root size — many design systems use 16 px; some apps set 10 px for easier mental math.
Example: 2 rem at 16 px root = 32 px. 48 px at 16 px root = 3 rem.
Common questions
What root size should I use?
16 px is the browser default and most common. Match your project's html { font-size } if it differs.
rem vs em?
rem is always relative to root. em is relative to the parent element — this converter is for rem only.