Convert between px, rem, em, pt, vw and vh with a configurable root font size and viewport — see every equivalent at once.
Updated
Relative units need a reference. Defaults match a typical browser.
Quick start
Enter a value, set the context, copy the equivalent — all in your browser.
Type the number and choose px, rem, em, pt, vw or vh.
Adjust root font size and viewport size so relative units resolve correctly.
Click any result card to copy that value with its unit suffix.
In-depth guide
CSS length units fall into two camps: absolute (px, pt) and relative (rem, em, vw, vh). Converting between them requires context — a root font size for rem/em and a viewport size for vw/vh. This tool does the maths in your browser and shows the equivalent value in every unit at once, so you can swap a hard-coded pixel value for a responsive one with confidence.
:root / html) font size; the go-to responsive unit.Reach for this converter whenever you inherit a fixed pixel design and want responsive CSS:
html { font-size: 62.5% } (a common 10px trick), update the root field or your rem values will be wrong.max-width: 100%.Every conversion is plain arithmetic executed in your browser. No values are sent anywhere, nothing is logged, and the page keeps working offline after the first load. There is no data to leak because the tool never talks to a server.
rem is relative to the root font size. With the default root of 16px, 16px = 1rem, 24px = 1.5rem, and so on. Change the root font-size field if your :root sets a different base, and every rem/em value updates to match.
em is relative to the font size of the current element, which cascades from its parent, while rem is always relative to the root. Because this tool has no element tree, it treats em against the same base as rem. In real CSS, an em inside a parent with a larger font-size will resolve to more pixels.
1vw is 1% of the viewport width and 1vh is 1% of the viewport height. The tool uses the viewport width and height you supply (default 1280×800), so 50vw at 1280px wide equals 640px. Adjust the viewport fields to match the device you are targeting.
CSS defines 1 inch as 96px and 72pt, so 1pt = 96/72 = 1.333…px, and 1px = 0.75pt. Points come from print typography; for screens you almost always want px or rem instead.
rem is generally preferred for typography and spacing because it scales with the user's browser font-size preference, improving accessibility. px is fine for borders, hairlines, and anything that should stay fixed regardless of zoom or root size.
No. All conversions are arithmetic performed in your browser. Nothing is uploaded or stored — the page works fully offline once loaded.
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