EMs to Pixels Converter
Convert ems to pixels and pixels to ems with a customizable base font size. Includes presets (16px, 14px, 18px), formula, and quick reference table for common CSS values.
Full original guide (expanded)
EMs to Pixels Converter
Pick your base font size, type a value in em or px, and get the converted CSS unit instantly. Perfect for responsive design, typography tuning, and UI guidelines.
Most browsers default to 16px.
em → px
px → em
Result: px from em
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Result: em from px
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Also useful
If root is 16px, 1rem = 16px.
Formulas
px = em × base_px
em = px ÷ base_px
Where base_px is the computed font size of the element you’re sizing — often 16px, but it could be inherited from any parent.
Quick em → px table (base 16px)
| em | px |
|---|
Change the base above to recalc for another design system.
em vs px vs rem
px is absolute (device pixels, or CSS pixels). em is relative to the font size of the current element. rem is relative to the root element (usually <html>). That’s why it helps to convert between them when following a design spec.
When to use em
Use em when you want child elements to scale if the parent’s font changes (for example, padding relative to text size).
When to use px
Use px for pixel-perfect layout elements that must match a specific spacing baseline.
FAQ
1. Why is my result not matching the browser exactly?
Because the actual computed font size in the browser might not be 16px, or you may have zoom/OS scaling. This tool assumes a clean base.
2. Can I use this for rem?
Yes — just set the base to your root font size (often 16px or 10px) and treat em the same way.
Formula (LaTeX) + variables + units
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px = em × base_px em = px ÷ base_px
- No variables provided in audit spec.
- NIST — Weights and measures — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/weights-and-measures - NIST — SI units — nist.gov · Accessed 2026-01-19
https://www.nist.gov/pml/owm/metric-si/si-units
Last code update: 2026-01-19
- Initial audit spec draft generated from HTML extraction (review required).
- Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
- Confirm sources are authoritative and relevant to the calculator methodology.